Frequently Asked Questions

Who is this company?   DIVA Automation is a sole proprietorship owned by W. Howard Speegle.

Where are they located?   DIVA Automation offices are located near Huntsville, AL, and in Staufen, Germany.

How long have they been in business?   Howard Speegle has been developing high performance motion controls under contract since 1981. DIVA Automation was formed in 1997.

Who do they sell to?   DIVA Automation has historically sold only to a select group of European OEMs who bundle DIVA products with their mechanical stages for subsequent sale to educational and industrial customers of all types.

How does their product compare with the competition?   DIVA Automation products have unparalleled cost vs. performance in comparison with other suppliers, and unexcelled reliability.

How do we know it will work?   DIVA Automation is the only supplier in the industry with a perpetual guarantee. If it ever breaks due to faulty design or manufacture, then we will replace it or repair it free of charge. New OEM customers may obtain evaluation units free of charge.

How soon can we get it?   Small quantities are usually available from stock. Production quantities require 6-14 weeks, depending on type and quantity.

How long will it take to apply it?   Just a bit longer than taking it out of the box and applying power. Ease of use is the #1 feature of DIVA products.

How much does it cost?   Less than similar products from anyone else. When DIVA is involved in the design of the complete system, the total system cost is frequently reduced by an amount greater than the cost of the DIVA product. Let us help you specify your system.

How hard is it to use?   Ease of use is the #1 feature of DIVA products. Our goal is to provide you with a tool, not to impress you with the difficulty of servo dynamics.

What do we do if it breaks?   If we can't help you fix it through e-mail and telephone communications, then we will send a replacement unit for your use while your unit is repaired.

What kind of warranty do they have?   Reliability is another #1 feature of DIVA products. DIVA Automation is the only supplier in the industry with a perpetual guarantee. If it ever breaks due to faulty design or manufacture, then we will replace it or repair it free of charge.

General

Where are your products manufactured?   We use ISO-9xxx-certified assembly houses in the U.S. and Germany. Production is usually assigned to the closest factory to the customer in order to reduce shipping time and expense.

What do you mean by perpetual warranty?   Reliability is another #1 feature of DIVA products. DIVA Automation is the only supplier in the industry with a perpetual guarantee. If it ever breaks due to faulty design or manufacture, then we will replace it or repair it free of charge.

Are Diva products lead free?   Yes. All DIVA products are available with RoHS certification.

What about obsolescence? Will I still be able to get the same product 5 or 10 years from now?   We will provide the same product for as long as you need it. As the electronic industry changes, there may be occasions when we will suggest an updated circuit to reduce costs or production lead times, but the choice is yours. We are sometimes forced to increase pricing on older products as our suppliers increase their prices to give us an incentive to convert to newer devices.

Can Diva provide me with a custom solution to meet my unique needs?   Absolutely! In fact, we are the only supplier that does not charge for customization of our standard products to OEM customers.

Can I try a Diva controller before buying it?   Certainly! Just ask for an evaluation unit. At the end of a reasonable evaluation period, you may return the unit or purchase it.

Do you charge extra for your software?   Never have. Never will.

Does Diva specialize in any particular industries or applications?   DIVA does not, but most of our OEM customers supply the micropositioning/ nanopositioning market. Any application requiring high performance coupled with high reliability and low cost is ideal.

How many people are employed by Diva?   As many as four, not counting our outsourced manufacturing.

How long has Diva been developing motion controls?   Howard Speegle developed a high speed precision pick-and-place robot in 1981. All of our products are descendants of and improvements on that design.

What is the hardware product history?   Following the original pick-and-place robot, a general purpose servo control product was developed in 1985, which was quickly followed by the industry's first multi-axis PC plug-in servo controller in 1986. Many versions of this controller have been developed since 1986, but all have maintained the same easy-to-use set of programming mnemonics. More modern, faster versions of the microcontroller have replaced the original and the chip count has been reduced to a realistic minimum, but anyone who bought our original DC-4 in 1986 can use the same program written for it to control any of our latest models. By the way, one of our biggest competitors bought S/N 1 of the DC-4 and subsequently released a similar product. In 1997, we began offering the basic circuit without motion control firmware or drivers for use as data acquisition products or general purpose computing. We are now offering the bare microcontroller with our proprietary program installed as a standard product for those wishing to construct their own control product. Extensive design support, including a reference design are provided.

Why use Diva products?   They are easier to use, are just as reliable, have better support and cost less than those from any competitor. You can pay more, but you may not get more, although there are certain features that we do not attempt to provide that are available from some competitors.

How many units are in use?   There are over 10,000 Diva-developed motion controls in service.

Where are they used?   Our products are in use in 40 countries around the world. Known installations include all continents except the Arctic and Antarctic, but there could be unknown installations there.

For what applications?   Applications of our controllers have ranged from focusing multifaceted telescopes to positioning specimens in electron microscopes to making sculpted carpet, to stacking magazines. Our products are so easy to use, cost so little and are so small that they can be used for any reliable positioning purpose.

How good is the support?   We regard field support of our products as the highest priority. When a problem is reported, we apply all available resources to its resolution in a timely manner.

How good is the warranty?   In order to survive in such a performance-competitive market, we had to design our products to the highest levels of industrial quality. In so doing, we achieved product reliability levels that have allowed us to support an unlimited warranty. We could not have survived the support requirements for 25 years if there were a measurable failure rate in our products.

How soon can I get an evaluation unit?   Depending on the product, you can have one from stock or up to six weeks.

Business

What is the cost of the system software?   Diva takes pride in supplying all software at no charge.

Can we get an evaluation unit?   Of course. Why should you be expected to buy a product without knowing how it will work in your application. In the past 25 years, we have had one customer return one of our controllers as unsuitable because it lacked a voltage-feed-forward feature. We were happy to return his money.

Do you accept purchase orders?   Yes, from qualified customers.

What currency can I pay in?   Payment can be made in US$Dollars, by credit card or in euro.

Do you accept PayPal?   No.

What payment terms do you offer?   We offer 30-day terms to all qualified customers.

Does Diva sell motors or power amplifiers/drives?   Yes. We are pleased to provide a matched set of motor with controller or motor, stage and controller with power supply. In fact, we heartily recommend this approach because it reduces our support requirements and saves both time and money for our customers.

What is your warranty period?   Our warranty does not expire. We still honor warranties on all products we have made, regardless of age. We recently repaired a controller we had sold more than 20 years ago.

Where can I get software or firmware updates for my controller?   The latest versions of all firmware and systems programs are available for download from our web site.

How do Diva controllers compare in price to other competing products?   Diva has always offered the best price vs. Performance in the industry.

How do I get a quote?   We are happy to provide quotations for any quantity and configuration. Simply visit our Quotations page.

Do you offer quantity price breaks?   Yes, of course. The price for quantities of 100 are typically 40% less than the single unit price.

Does Diva support international customers?   Very much so. In fact, the majority of our customers are located in the European Union. They, in turn, sell to over 40 countries. As an example, the first Western motion control sold in Russia after the collapse of the Soviet Union was designed by Diva.

Do you meet ISO9000?   All of our products are manufactured in the U.S. Or in Germany, by ISO-qualified assembly houses that are also able to certify products to RoHS and other standards.

Technical

How much software development is required?   All control programs for Diva products can be interactively developed using our DiMAC control language that is contained on-board. No high level language or cross compiler is required for use, although they may be used if preferred.

Is there enough storage for my program?   The efficiency and power of the DiMAC control language is such that we have never had an instance of a program that used all available memory.

What is the motor voltage, current range?   Depending on the product type, motors of 1-5 Amps may be controlled directly, using the on-board power drivers. Larger motors can be controlled through the use of external power amplifiers. The largest motors we have worked with were 3-phase, 400 Volt, 3 HP models.

What size motor can I drive?   There is no fixed limit. We have controlled motors from 3 mm diameter to 3 HP.

How much EMI does it generate?   When EMI is a consideration, we recommend the use of our controllers that have analog output. We also recommend that the driver be placed as near as physically and electrically possible to the motor. When CE EMI certification is required, then the controller should be mounted inside a shielded cabinet. Several Diva products have been CE certified by our customers.

How much heat does it generate?   Diva controllers are extremely energy efficient and typically require less than a half watt for operation.

What environmental conditions can it tolerate?   The operating temperature range is from -40 C0 to +125 C0. Our products are designed to be used in both laboratory and factory floor environments. If there is a question regarding the suitability of them for a particular application, then please send a description of the required environment. The most rigorous environments we have dealt with were temperatures to 200 C0 and submersed in boiling sea water while being pounded with nearby torpedo explosions..

What is the size, weight?   Our largest controller is a half size ISA-bus PC plug-in board. Our smallest fits onto the back of a 22 mm motor encoder. The weight is only a few ounces.

Does it require a fan?   None of our products require a fan for normal operation. However, the maximum useful motor power can be increased with increased air flow across the motor driver chip.

Where can I mount it?   We design our controllers to minimize the size so that they may be mounted where required. Some are designed to be mounted on the motor or in the same housing with a motor. Others are mounted inside a PC cabinet, while others are either mounted in rack chassis with other system electronics, on a DIN rail or a lab bench.

What is the loop update rate?   Our fastest update rate is 10 KHz, but most operate very satisfactorily at much lower rates, such as 2.5 or 1 KHz.

Do the features match my application?   We will be happy to provide assistance in your selection and/or send you an evaluation unit.

How can I tell for sure?   You may either order a completely integrated electromechanical system from Diva or use our evaluation unit in your setup.

How hard is it to use?   To quote our first customer, "Make it as easy to use as a screwdriver". This philosophy has been our driving force throughout our business life.

What programming language do I need to know?   You don't need to know any language. As long as you are able to describe the operations you wish to perform, you can use a Diva controller. Of course a bit of practice is required for full competence, but non-technical salesmen are usually able to make a good demonstration of the controller within a few minutes. There is no need to use a "hired gun" to write software no one understands when he leaves.

How many commands are supplied on board the controller?   The number varies according to the product type, but it ranges from more than 50 to more than 100.

What does PID mean and why do I care?   PID refers to a technique used to make a system run smoothly. In motion control, we want the power applied to the motor to be Proportional to the difference between the actual position and the ideal position. This accounts for the P. We would also like to be able to apply more power if the friction is higher in some spots, causing the difference between the actual position and ideal position to remain greater than normal. In order to build up more power, we Integrate (sum up) the difference over a period of time. This accounts for the I. We also want to prevent overshoot, so we Differentiate the error. (Calculate the differences in the error). This accounts for the D. Taken all together, the P, I and D terms are referred to as a PID filter. Applications that have high friction or high inertia can benefit considerably through use of a PID filter.

What does PWM mean and why do I care?   A technique we sometimes use for driving motors at very high efficiency is to use digital control so that the power is either fully on or fully off at all times. When it is full off, very small amounts of power loss is converted into heat. When it is fully on, a bit more power is lost through heat, but much less than if the output transistors were kept partially on. In order to be able to vary the total power over a range from completely off to completely on, we vary the percentage of time that the power is applied to the motor. In other words, we control the power level by controlling the pulse width. PWM stands for Pulse Width Modulation. Motor drivers that apply PWM techniques are physically smaller, cost less and generate less heat than analog drivers.

What does multi-drop mean and why do I care?   It is possible to connect 16 or more Diva controllers to a single RS-232 channel and to communicate with each one individually by sending a command to select the active controller. It is possible to construct systems with many motors controlled through a single communications port without special equipment.

How long does it take to set up your controller?   Diva products are set up with typical values for normal operation at the factory. Although the process of optimizing the setups is very straightforward, it is entirely optional in most cases.

Do you offer custom applications?   Most of our customers order custom variations of the controllers that we offer them. The variations range from minor to complete designs. Diva Automation is the only supplier of motion controls that does not charge for custom engineering of OEM controllers.

What is the speed range? How slow can you go?   Most of our controllers are limited to an upper frequency of 1 MHz encoder rate, but we are able to support rates of up to 20 MHz when needed. The velocity is programmed in units of one encoder count per second, so the lowest speed we can support is 1 count per second. This does not indicate that we suggest use of such a slow speed for applications where smooth motion is critical because stiction friction becomes a very important consideration under these conditions, causing jerky motion in many cases.

What status reporting is provided?   The TS (Tell Status) command provides an extensive report of the system status, including errors in programming or motion, limit switch actual state and programmed states, numeric mode in use and many other parameters.

What is the maximum baud rate?   The maximum standard baud rate is 38,400, but higher rates may be supplied on request.

Are values expressed in decimal or hex?   Two commands are provided to allow selection of the number system. The default number system is decimal, which can be changed to hexadecimal using the HM (Hex Mode) command. When in hex mode, all numbers entered and displayed will be in hexadecimal format. The DM (Decimal Mode) command returns the mode to decimal.

What OS can be used?   Any OS can be used for system programs, although the system programs supplied by Diva are only compatible with DOS and Windows. The only requirement for user-written software is that it must be capable of sending and receiving ASCII strings.

Are drivers available for LabView? C++?   A driver is available for LabView. No C++ functions are available.

What type of processor do you use?   We use a Renesas microcontroller in most of our products. Our higher performance servo controllers use a dedicated servo control processor for National Semiconductor, the LM629.

How many bits, clock rate, etc.?   The CPU is 8-bits at 8 MHz which is well suited for servo control at up to 10 KHz servo update rates.

What is the servo update rate?   From 10 KHz, depending on the product type and requirements

Can it be controlled with step and direction pulses?   Some of our products accept step and direction controls, but this mode of operation removes much of the value of the stored program features provided.

Which amplifiers/drives/motors does Diva recommend?   Nearly all Diva controllers have on-board drivers for the most widely used motors. However, when these drivers are not large enough to drive the selected motor, then we recommend driver amplifiers from Advanced Motion Controls in Camarillo, CA. We find that nearly all of our customers use motors made by MicroMo (Faulhaber) or Maxon, although any DC motor can be used. The final selection must be made based on many factors that include torque, RPM, voltage, size, weight and cost.

Do all Diva controllers share the same programming interface?   Yes. Any Diva controller uses the same basic control language, DiMAC.

How are Diva controllers programmed?   A very straightforward manner of programming our controllers is to develop macro commands using the interactive commands built into the controller. These macros serve the purpose of functions in a high level language. When macros have been developed for all functions, they may be called in sequence control programs that are stored as additional macros or called from a host program.

Do Diva controllers support non-volatile storage of axis parameters?   Yes. All Diva controllers provide non-volatile storage.

Can I store multiple sets of axis settings (PID gains and trajectory)?   You may store additional setups limited only by the amount of memory available. Macro commands are typically used for this purpose.

Do I need to learn a proprietary language to program a Diva Motion Controller?   In a sense, yes, but learning to use DiMAC is unlike the process of learning a high level language. All that is required is to learn a few two-letter codes that are shorthand for the action to be taken. MR is the command to move to a position relative to the current position. MR1000 will cause motion of 1000 encoder counts in the positive direction each time it is given. MA1000 will cause motion to an absolute position of 1000 encoder counts from the position at which "home" was established. If the current position is already equal to 1000, then no motion occurs. To make full use of the language, the codes (mnemonics) for all available functions must be learned, but it is only necessary to learn a small group in order to make use of the controller.

Can I use more than one Diva motion controller in a computer?   Diva plug-in controllers have address switches that allow use of a number limited only by the number of available slots. Most Diva controllers use a serial interface that supports 16 or more controllers on a single port. An additional 16 controllers may be connected to each available port. When USB to RS-232 converters are used, USB hubs may be used to connect as many controllers as desired. Some of our controllers have been used in applications with more than 1000 controllers operating simultaneously.

Can I use a tachometer for velocity feedback?   Diva controllers do not provide a dedicated input for tachometers, nor is one required for operation. However, most of our controllers have general purpose analog inputs available that can be used to report the tachometer voltage, if desired.

Does the servo loop rate of your controllers depend on the number of axes being controlled?   No. Each axis under control has at least one, and sometimes two, dedicated processors. No motor shares servo loop resources with another.

How long does it take to execute a command?   Some commands require more processing time than others, but none require more than a few microseconds. A processing rate of 5,000 per second is typical.

How many commands are built in?   The number of commands varies with each controller, but is normally in the range of 50-110.

What is the command format?   All commands have a two-letter code. They may be given as single commands, or as a string of commands separated by commas. For instance, MR1000 causes a motion of 1000 encoder counts in the positive direction. MR1000,WS500,MR-1000, WS500,RP9 performs a complete function. It asks for motion of 1000 encoder counts in the positive direction, then a wait of half second (500 ms) after completion of that move, followed by a motion of 1000 counts in the negative direction. After having been stopped for another half second, the entire process is repeated nine times. In other words, a cycle of 1000 counts in either direction will be performed ten times, with short delays at each end of travel. This action can be defined as a macro command by simply preceding it with a macro definition command and number. MD3,MR1000,WS500,MR-1000,WS500,RP9 defines macro number 3. The ten cycle motion can be performed with the command MC3.

Can I add more commands?   Additional macro commands may be added to the limit of the memory. To add native commands, DiMAC uses a table to store the calling code and the address of the routine to be executed, as well as other syntax descriptions. Adding a command consists of writing a routine to be executed, plus adding these entries to the table.

Will Diva add commands for me?   We will be happy to do so.

How long will it take and how much does it cost?   Most commands can be added in an hour or less. If a command is complex, requiring longer periods, the cost depends on whether the command has general interest or is specific only to the requester.

How many commands can be added?   Commands are limited only by the amount of available memory and the desire to make them mnemonically consistent with the action to be performed. For instance, TA is already assigned to the Tell Analog command, so TL was used for reporting the stored value for acceleration. Any two characters can technically be used.

Will it work with a MAC?   Any computer capable of sending strings of ASCII data can be used to control Diva controllers.

Will it work under Unix/Linux?   Any operating system capable of sending strings of ASCII data can be used to control Diva controllers.

How can I tell if the motor is connected properly?   A DC motor has only two wires. If the motor runs away from the desired position when the loop is closed, then it is probably wired wrong. If reversing the motor leads does not resolve the problem, then the encoder may not be wired correctly.

How can I tell if the encoder is connected properly?   If the position reported with the TP command changes as the encoder is moved, then it is probably wired correctly. The direction of motion considered to be positive can be changed by exchanging the signals from channel A and channel B. However, if the motor was stable before this change, the motor miring must also be reversed in order to remain stable (not run away).

How can I test the limit switches?   The TS Tell Status command can be used to read the state of the limit switches. They can be activated manually or by moving the stage to the end of travel.

Why does the motor stop before it gets to the target position?   The proportional gain of the servo loop applies a variable amount of power to the motor, depending on the distance from the intended position. If the value of the P gain is set too low, then the amount of power applied to the motor could be too low to overcome the friction of the lead screw. Try increasing the proportional gain.

Is the source code available?   The source code is made available only with the purchase of a full manufacturing license. Please contact the factory if interested in purchasing a license.

Can Diva Motion Controllers be used stand-alone (no host computer)?   All Diva controllers that are not PC plug-in types can be used in a stand-alone mode. If operation from a stored program is desired, then a host computer or other form of terminal is normally used to initially store the program. We do offer an optional SOS (stand-alone operating system) that provides full control using only two switches and a variable voltage input.

What type of feedback sensors does Diva support?   Any form of incremental position encoder may be used with the standard configuration. They may be rotary or linear encoders or interferometers, as long as there are two TTL-level channels with pulses spaced at 900. Other types of position feedback, such as absolute digital encoders, LVDTs, resolvers or strain gages may be used with suitable adapters.

What type and size of motors can be controlled by Diva motion controllers?   We make controls for DC motors and sometimes for stepper motors. The size that can be controlled is determined by the motor driver, not by the controller. The drivers incorporated into our controllers can drive up to 3 A. Larger motors require external drivers. If external drivers are used, then the motor may be either a brushed or brushless type. The on-board drivers are only designed for brushed motors.

What kind of amplifier do I need to drive my motor?   The drivers incorporated into our controllers can drive up to 3 A. Larger motors require external drivers. If external drivers are used, then the motor may be either a brushed or brushless type. The on-board drivers are only designed for brushed motors.

Does the controller support a unique serial number for each unit?   The SN command can be used to store a four digit serial number, which can be read out using the RN command.

Can the serial number be hidden from the end user and used only for security?   We also support a hidden 8-digit number that is assigned and read out by means undisclosed to anyone other than the OEM who has made special arrangements with the factory.

How is the address assigned to each controller in a multi-drop arrangement?   To assign an address, disconnect all other controllers and use the DB command to assign a board number.

How can I read the address of the selected controller?   The TB command can be used to read out the number of the last selected board.

How can I select which controller to communicate with in multi-drop?   A sequence consisting of a ctrl-A character is sent, followed by the board number. All boards with other addresses are deselected and any board that matches the number is selected until another address selection sequence is issued. This allows the use of a special broadcast address to be used to send data or control commands to all board simultaneously.

Can macro commands be stored in ROM?   Yes. Please contact the factory for instructions or for programming services.

Can the controller's command interpreter be bypassed by the host program?   All Diva controllers provide a mechanism that allows host program access to all internal functions and features. This feature is recommended for advanced users only.

What types of amplifiers can be used?   Based on the individual product, either analog or digital PWM driver/amplifiers can be used.

What servo update rate works best?   This is dependent on the dynamic characteristics of the electromechanical system. For typical leadscrew-driven stages, a 1 KHz update rate provides excellent performance. A voice coil-driven actuator might need 10 KHz updates, or faster. Various Diva controllers provide 1-10 KHz update rates.

Can I use a calibration table to improve positioning accuracy?   This feature is not built-in to any Diva standard product, but we will be happy to work with any customer who would like to apply this technique.

What is the debugger and what can be done with it?  v The debugger is an on-board monitor that provides bit and byte-level access to all memory and peripheral ports of the controller. Total access is provided to all system resources.

Can I download new firmware through the comm port?   Some Diva controllers provide this capability.

How many axes can be supported?   There is no fixed limit to the maximum number of axes that can be controlled simultaneously by a host program using interconnected Diva controllers. Most Diva controllers support only one axis directly. The largest number supported by a standard product is three. The largest number we have provided under special order was 1024.

How much I/O can be supported?   Some Diva controllers have no available channels of external I/O. Some have up to 72 channels. Most Diva controllers have 6-18 channels, usually depending on available space for connections. It is possible to add external slaved I/O expanders on special order.

How much memory can be supported?   The typical amount of non-volatile memory provided for program storage is less than 2 KB, which is adequate for most applications. When more memory is needed, it is possible to increase the size up to 512 KB on special order.

What can the I/O signals be used for?   The Diva Automation I/O channels can be used to sense the position of external switches, read keyboards, drive LEDs and LCDs, read voltages, drive relays or acoustic generators, read resistance, temperature, pressure, pulse width, frequency or just about any other function normally performed by laboratory instruments.

What is the input voltage range?   For most of our products, the range is limited to 0-5 V. However, some Diva controllers provide optical isolation to extend the range to 24 V or higher.

What is the output current and voltage range?   Most Diva products provide 2-10 mA at 5 V, maximum. However, some products have built-in drivers to extend the range to 400 mA and 24 V or higher.

What is optical isolation and why do I care?   Optical isolation involves the use of an LED that is driven by the external signal and a photosensitive transistor that is controlled by the illumination provided by the LED. This allows much higher voltages to be input to a 5 V system without damage. It also provides some degree of filtering for signals with a lot of noise. Two of the most valuable features of optical isolated inputs are additional safety protection against high voltage and the use of very long cables without error.

Are limit switches supported?   Yes. All Diva Automation motor controllers provide two limit switch inputs for positive and negative motion.

Does it meet CE certification requirements?   Diva Automation does not certify its products to CE requirements. They are intended as components in a larger system, which is certified by the system manufacturer. All of our products are designed to the intent of the CE requirements.

Does it meet UL certification requirements?   Diva Automation does not certify its products to UL requirements. They are intended as components in a larger system, which is certified by the system manufacturer. All of our products are designed to the intent of the UL requirements.

Does it work with resolver inputs?   Only with a special adapter.

Does it work with LVDTs?   Only with a special adapter.

Does it work with absolute encoders?   Only with a special adapter.

Does it work with linear encoders?   Yes.

Does it work with dual loop encoder inputs?   Only with a special adapter.

Does it work with stepper motors?   Only models specially defined as stepper motor controllers.

Does it work with brushless motors?   Only through use of an external amplifier designed for brushless motors.

Does it have velocity feedforward?   Only in certain models.

Does it have acceleration feedforward?   Only in certain models.

Is it suitable for use as a CNC controller?   We do not recommend our present controllers for this purpose.

Is a PLC required?   Not for normal operation. In many cases, the integrated I/O capability of Diva controllers can eliminate the need for a separate PLC in the system.

How can I connect multiple axes?   Simply interconnect multiple Diva controllers. Some of our controllers provide two DB-9 connectors, making it very easy to "daisy chain" multiple controllers. Others use a flat ribbon cable with multiple connectors installed.

Can I store the position so it is not lost while power is off?   The position can be stored, but there is no way to know whether the position changed while power was off unless some special method is applied. If this is an important consideration, please contact us to discuss the tools we have available for this type of application.

How can I synchronize the axes?   The standard I/O signals can be used to synchronize motion between related axes to within one thousandth of a second or less by interconnecting signals between the controllers.

How can I control simultaneous operation of multiple axes?   The answer to this question depends on the degree of "instantaneous" required. Simultaneous control to within 1 ms or less can be achieved by merely issuing a common "go" command. More involved techniques can be used for closer tolerances.

Does it work with gearhead motors?   Gearhead motors typically present less difficulty to control than those without gearheads.

Why does the driver get hot?   Analog drivers typically generate as much heat in the driver as is dissipated in the motor. A 10 W motor can increase the temperature of an analog driver to very uncomfortable levels. PWM drivers are much more efficient and do not normally get as hot as the same size analog driver. Motors generate much more heat when accelerating or stalled. Motor drivers generate more heat when the motor is accelerating, decelerating, stalled or oscillating. Most of our drivers are rated for operation at temperatures above 200 0F.

Why does the motor vibrate when it is stopped?   If the motor is vibrating, this could indicate that it is oscillating. If so, then the gain should be reduced until the oscillation stops. To detect oscillation, the TE command can be used to report the error between the target position and the actual position. If TE reports values that vary between positive and negative, then the motor is oscillating.

Why does the motor overshoot?   This happens when the load on the motor has so much inertia that the gain setting of the servo loop is not high enough to prevent it. The D term in a PID controller can be used to prevent overshoot.

Why doesn't the motor move?   There are many possible reasons for this. All of them come down to whether there is sufficient power available to move the motor and whether the control conditions are such that the need for a move is present. For instance, if the limit switches are defined incorrectly, the controller could thin that they are both activated, in which case, motion would cease before it began. This subject is too complex to be fully discussed here. Please consult the user manual for more details.

Why does the motor move in one direction and not the other?   This could be the result of a bad limit switch, bad wiring or a bad driver.

Are limit switches required?   Limit switches are required only for safety of personnel or equipment. If they are not used, then the LF command should be used to turn off the software limit switch action. Some controllers require an additional limit switch disable jumper to be installed, to prevent the hardware protection from disabling the motor signals.

Does it accept encoder index signals?   Yes. Most Diva controllers accept encoder index signals.

Does it accept reference switch inputs?   Yes. Most Diva controllers accept reference switch inputs.

Does it have a joystick mode?   Some Diva controllers have standard joystick inputs. Others can be supplied on request.

Does it support local position display?   Some Diva controllers support local position display. Others can be supplied on request.

Does it support a jog mode?   Some Diva controllers support a jog mode. Others can be supplied on request.

Does it support both single ended and differential encoder inputs?   Some Diva controllers support differential encoder inputs. Adapters for others can be supplied on request.

Are drivers provided for LabView and high level languages?   Some drivers are available. Please contact the factory.

Is a host program available?   Diva Automation provides a sample Visual BASIC host program at no charge.

Is there a virtual Instrument program available?   Diva Automation provides a sample Visual BASIC virtual instrument panel program at no charge.

What accuracy can the controller achieve?   The accuracy of positioning is not determined by the controller, but by the mechanical system characteristics. Our controllers are compatible with the accuracy of any system.

What resolution can the controller achieve?   The positioning resolution is not determined by the controller, but by the position measuring characteristics. Our controllers are compatible with the resolution of any system.

Can different types of motors be connected on the same comm channel?   Any mix of Diva controllers can be controlled through a single communications channel. All use similar addressing and multiplexing methods even though they might use very different commands.

Can different size motors be connected on the same comm channel?   Any mix of motor sizes and types can be connected on a single comm channel.

What is the maximum velocity that can be supported?   The measuring resolution of the position encoder is the limiting factor here. Most Diva controllers accept encoder rates of up to 1 MHz. If the encoder is a linear one with 10 micron lines, then 1 MHz would relate to 250 meters per second, which is much higher than most linear encoders can provide. A 1000-count rotary encoder with a 140:1 gearhead and a half mm leadscrew pitch will move at less than 1 mm per second when the encoder is generating 1 MHz.

What is the maximum acceleration that can be supported?   The maximum acceleration is determined by the electromechanical system. Our controllers can support any practical acceleration rate.

How can I tell what size motor I need?   This is an excellent question and one for which there is no ready answer. Motors are usually chosen by very nonscientific methods. If the chosen motor is too small, it will usually be increased. If it is too large, it is unlikely that any change will be made. The factors governing the proper motor size are functions that are usually chosen without any firm basis due to lack of education regarding their proper selection. Many systems are specified to accelerate to full speed within one second simply because that is a convenient number for use in calculations. Acceleration is one of the primary determinants in motor power requirements Another very strong determining factor is the pitch, material and diameter of the lead screw. It is normal for the lead screw to consume 95% of the motor power when accelerating at typically selected rates. By changing one of these factors, the motor size might be reduced by as much as 50-90%. In addition to increasing the cost of the motor, over specification also increases the cost of the motor driver and power supply. The cost of motor drivers varies somewhat linearly with power requirements, but there are step functions in cost and size when moving from one range to another. The easiest approach to motor selection is to purchase the motor as part of an integrated motion stage.

How can I tell what motor voltage to choose?   In general, it is better to select the highest winding voltage that is a standard product. The important characteristic to the system performance is motor power which is controlled by the product of voltage and current. Therefore, by choosing a 24 V motor winding instead of a 12 V motor winding, the same amount of power is available at half the current. In motor driver circuits, the amount of current switched is the determining factor, so a given driver can control a 24 V motor with twice the power of a 12 V motor.

How can I tell what type of lead screw to use?   In general, the smallest diameter leadscrew, made from the lightest material, with the largest pitch consistent with other requirements is the better choice. When designing open loop systems using stepper motors, the accuracy and pitch of the lead screw threads was a major considerations. When using a DC motor with a gearhead, the servo control function in conjunction with a position feedback encoder reduces the demands on the lead screw to a large degree.

What is lead screw pitch and why do I care?   The pitch is the distance between threads on the screw, or the distance the stage moves with one complete revolution. A finer pitch provides a mechanical advantage over a more coarse pitch, but possibly at a cost to other more important functions without any particular benefit from the mechanical advantage. A fine pitch lead screw requires less force to turn that a coarse pitch screw, but requires more power to accelerate to the same end velocity.

What is the servo loop bandwidth?   Servo loop bandwidth is a measure of the response time of the controller to an error in position. Properly matched and set up controllers provide a correcting force to position errors that are in line with the physical response time of the mechanical system.

What is non-volatile memory and why do I care?   Non-volatile memory retains stored information when power is off. The working memory in most controllers is RAM, which normally loses all stored information when power is removed. Diva controllers store setup information in non-volatile memory so that it does not have to be entered again each time that power is applied.

How can I set up the PID gains?   The procedure for choosing the optimum values for the PID gains is too involved for this discussion, but the actual setting up is done with the DP, DI and DD commands. When the values have been calculated, these commands are used to enter them. If they are to be the normal values to be applied at power up, then the UD command can be used to update the non-volatile memory storage.

How fast can I read the position?   This is a very common question from those not familiar with Diva controllers. They are expecting that the burden of monitoring position to determine the end of move is the responsibility of the host program, therefore a high read rate is necessary. However, Diva controllers provide multiple means of monitoring and reporting the position status. A simple command such as MR1000,WS,TE will initiate motion and report the distance from the target when the motion trajectory has completed. A more useful command line would be MR1000,WS500,TE. This allows a half second for the motor to settle at a final position before reporting.

How can I synchronize the motion with my program?   By using the technique described above, as well as others provided in the DiMAC language, the host program can easily be synchronized with the mechanical system.

How do I know when motion is complete?   A command like the one above that reports after motion is complete is one option. It is also possible to use the TS command to monitor a status flag that indicates whether motion is complete.

What is a macro command and why do I care?   Macro commands are command lines that have been identified as macro commands and can be used in a program as if they were native commands. TP reports the position. TE reports the distance to the target. A command line of TP,TE reports both. Creating a macro with the MD command only requires assigning a number. MD7,TP,TE will create macro number 7. It can be used in place of entering TP,TE by entering MC7. Most applications can be implemented by defining a few macro commands and calling them from other macros.

How many macro commands can I store?   Most Diva controllers store at least 15 macros. Some store more. The number is limited only by the available memory. Macro commands use seven bytes of memory for each included command, plus one byte for length information.

What is special about Macro #0?   Macro #0 is implemented in a similar manner to the DOS AUTOEXEC.bat program which executed automatically when power was applied. This capability allows the implementation of completely automatic, stand-alone systems. MC0 can be defined to set up any special conditions, then wait until a start switch is pressed to transfer control to the other macros that constitute the main program of the system.

Can I assign names to macros instead of numbers?   This capability is included in a host program we supply, but it is not a supported function on board.

How can I communicate with the controller?   Most Diva controllers use RS-232 for host communications. When an RS-232 port is not available, there are many USB "virtual RS-232" devices available at low cost. Interested OEMs may inquire regarding the inclusion of USB interfaces on-board the controller.

What baud rates can be used?   Any baud rate up to 38,400 can be used.

How can I make the program skip over an action if a part is missing?   Conditional execution commands are available to execute or not execute a command or portion of a program based on the state of an input. The inputs may be real analog or digital signals from an external source or virtual channels based on internal status flags.

How many I/O lines are available?   Most Diva controllers have at least six channels, although the smaller embedded controller have none due to inadequate connector space. Some have as many as 72.

How many can be used as inputs?   All can be used as inputs unless they are dedicated to high power outputs through a driver.

How many can be used as outputs?   All can be used as output unless they are dedicated to optically isolated inputs.

How much current can the outputs supply?   The ports that are supplied directly from the microcontroller can supply 2-10 mA. Some controllers have a 400 mA power driver for four channels.

What voltage can they accept?   All can accept 0-5 V levels. Optically isolated inputs can accept 24 V or higher.

Does the controller accept analog inputs?   Most of our controllers have at least one analog input channel. Some have eight channels.

What is the voltage range of the analog inputs?   All are limited to 0-5 V range.

What is the load impedance?   The load impedance is > 10 K ohms.

How fast can they be read?   The internal read speed is less than 40 microseconds. When reporting through the command level, the reported value is within 1 ms of actual state.

How can I read them?   A TA command is provided to Tell Analog. Without a channel number, all available channels are reported. TA3 will report only the value of channel 3.

What is the resolution of the analog inputs?   Except for the dedicated data acquisition controller, DAQ-1212, all of our controllers provide one part in 256 (8-bit) resolution. (0.4%) The DAS-1212 has 12-bit resolution.

Does the controller provide analog outputs?   Most Diva controllers have one or two analog outputs. The DAQ-1212 has 8 analog outputs.

What is the voltage range?   Most are 0-5 V. The DAQ-1212 has +/- 10 V outputs.

What is the resolution?   Most are 8-bit. The DAQ-1212 has 12-bit resolution.

What is the current available?   Most are 2 mA outputs. Some have 1 A buffers.

How do I control the analog outputs?   The SO command sets the output. IO increments by a positive or negative value and TO reports the current setting.

How fast can they be updated?   Through the command interface, approximately 5-5000 times per second. Through the ISA bus, as fast as the bus can transfer the data.

Does the controller supply power to the encoder?   Yes. All of our motor controllers supply 5 V for encoder power.

Why doesn't the controller respond when I send a command?   Most Diva controllers require that an address selection sequence be sent before they will respond.

How can I connect a USB port to your device?   We use a variety of commercially available USB to RS-232 converter cables. They are low cost and work well.

Are the digital outputs open collector or active pullup?   Most Diva controller outputs have active pull-ups. A few are open collector type. When a limit switch is detected, does the motor stop smoothly or abruptly. When a limit switch is detected, it is assumed to represent an emergency condition, so most of our controllers stop as quickly as possible, although some provide the option of a controlled or abrupt stop.

What units are used when programming velocity and acceleration?   Velocity and acceleration are programmed in units of encoder counts per second.

What units are used when programming delay times?   Delay times are programmed in units of milliseconds. A WA command with no data will cause a delay of 1000 ms (1 second). WA500 will delay 500 ms.

When I tell the motor to move forward, then reverse, why doesn't it move?   Commands are executed much faster than a motor can move. If a command to move in one direction is followed immediately by a command to move the same amount in the other direction, the sum total of requested motion is zero. In order to cycle between two positions or to synchronize other actions with motion, it is necessary to insert delays that allow time for the motion to be performed. Two types of commands are provided for inserting delays into the program. The WA command begins counting down as soon as it is executed, without regard to whether any requested motion has been completed. The WS command does not begin to count down the delay until after the end of the motion trajectory. This is the command normally used to sequence a cyclic motion. A third delay command, WE, is available on some Diva controllers. It is used to delay execution until the difference between the target position and the actual position is within a given amount. WE10 will wait until the position is within 10 encoder counts of the target. If the motor never reaches this tolerance for any reason, the wait will be indefinite.

Can I use a limit switch input as a reference switch input?   Yes. Simply connect the limit switch signal to the reference switch input.

Does the controller support contouring motion with multiple axes?   Yes, but not to the degree of precision required for CNC-type operation. Any contouring motion must be implemented by the host program by sending commands to the individual controllers to achieve the desired contour.

How do I program a homing sequence?   Two types of commands are provided for enabling a precise and repeatable homing sequence. All Diva motor controllers have an FE command which is used to search for a reference switch input. For increased accuracy, so also provide an FI command to also search for the encoder index signal which is much more precise than most reference switches.

What happens when I make a typing error? Can I backspace?   Diva controllers do not support on-line editing. If an error is made, the command must be entered again. If editing features are desired, then a host program must be used.

What is the maximum length of a macro command?   Most Diva controllers support up to 17 commands in a macro. Some support up to 35 commands.

How can I tell if the motor is moving?   The TP command reports the position of the encoder at all times.

How often can I read the status?   The TS command can be used to report status continuously except during the time when the controller is servicing the servo loop.

What is the maximum supported motor RPM?   The maximum velocity is determined by the encoder input signals, which can accept at least 1 MHz inputs. As an example, a 500-line encoder must run at 30,000 RPM to generate 1 MHz encoder signals.

How can I drive the motor continuously at a constant velocity?   Some Diva controllers offer a VM (Velocity Mode) command. For others, the FE command can be used to cause motion for two billion encoder counts.

How can I disable the limit switches when driving a rotary stage?   Some Diva controllers provide jumpers that can be set to individually disable the left and right limit switch inputs. For others, it is only necessary to use the LF command to turn off limit switch action.

How can I disable a single limit switch to allow motion in one direction only?   This can be done by installing only one limit switch disable jumper or the LF command can be used to disable individual switches. (LF1 or LF2)

Can I control motion entirely through local switches and displays?   Yes, some Diva controllers offer a unique capability of providing 64 operating modes that can be selected and controlled through the use of only two switch inputs and a variable voltage. The SOS option provides an additional stand-alone operating system in conjunction with DiMAC.

Is a host computer required for operation?   No. After downloading macro commands, all Diva controllers are able to operate autonomously. Controllers with the SOS option do not require connection at any time, although if macros have been downloaded, they may be executed under control of SOS switches.

Is a host computer required for programming?   No host computer is required. Any terminal or terminal emulator capable of sending ASCII strings is adequate for control and creation of macros. Controllers with the SOS option do not require connection at any time, although if macros have been downloaded, they may be executed under control of SOS switches.

How do I connect multiple controllers to a single comm channel?   Simply connect up to 16 controllers to the same signals. Some Diva controllers provide two connectors for this purpose. Others use a flat ribbon cable with multiple connectors installed.

Isn't RS-232 limited to a single device per channel?   No more than one device can be allowed to transmit simultaneously, so our controllers disable the RS-232 driver unless they are addressed. All controllers may listen simultaneously.

How many controllers can be connected to a single RS-232 port?   Up to 16 controllers may use a single port. If the host has sufficient drive, as many as 32 controllers may share the port.

What are subcommands and why do I care?   Several single-character commands are provided that can be issued at any time, even during execution of another command. They can be used to read position, status, etc., without disturbing a running program.

How can I read the current position without stopping the program?   Use the TP subcommand.

How can I read the version number and release date of the firmware?   The VE command reports this information.

Is it possible to expand the memory size?   Although it is relatively possible to expand the memory, there has never been a reason to do so.

How can I test the firmware?   A self test program is executed on startup. In addition, the CS command calculates a checksum of the entire contents of program storage. Any change to the contents will result in a change to the original result.

How can I make sure that the motor has completed the previous move before starting the next one?   The WS (Wait for Stop) command is included in all Diva controllers. However, it reports the completion of the motion trajectory generator. Under normal conditions, the motor will be very near the target position at this time. However, if a stall has occurred, when the trajectory is complete, the motor could be at any position. Therefore, to be certain that the motion has indeed occurred, it is necessary to use other means. Some Diva controllers provide the WE command which can be used to wait until the position has come within an acceptable tolerance from the target position. For controllers that do not support this command, we recommend that a WS command be given, followed by a TE command. WS500,TE will wait until 500 ms after the end of the trajectory, then report the distance remaining to be moved.

Can the programmable parameters such as gains and velocity be controlled through use of local devices such as switches or potentiometers?   Some Diva controllers support this feature. For others, it is necessary to use a host program to read the value of the switch or potentiometer and send the appropriate gain and velocity commands.

How can I assign "Home position"?   The DH command is provided to Define Home position. It can be used at any time.

Can a general purpose input be used as a limit switch?   Yes. However, the response will be slower and not as automatic.

Can an external parameter such as motor current or temperature be used to control program flow?   Some Diva controllers provide this capability.

Is it possible to limit the maximum motor torque?   Diva controllers with analog outputs provide an SQ command which is used to Set Torque.

Can the torque limit be changed during motion?   The torque setting can be changed at any time. A typical use would be to set the torque low when searching for a physical limit, in order to prevent mechanical damage. When the search is complete, the torque may be set to the normal limit.

Can the velocity be changed during motion?   Most Diva controllers support velocity change while moving.

Can the velocity be different for one direction than the other?   All Diva controllers support velocity change when not moving. It is very common to select different velocities for different directions.

Can different PID setups be used for loaded and unloaded conditions?   Absolutely! Any easy way is to define separate macro commands for each setup combination and to call these proper macro when commanding motion.

Can an emergency stop switch be implemented?   Any switch that simulates activation of both limit switches will prevent motion in either direction. When the active state of the limit switch is set low, using the LL command, grounding both switches performs a stop. A similar result is achieved when limit switches are defined as high signals, using the LH command. Also, the AB command or the ! Subcommand will stop motion until commanded again.

Can a "Dead man switch" be implemented?   Any switch that simulates activation of both limit switches will prevent motion in either direction. When the active state of the limit switch is set low, using the LL command, grounding both switches performs a stop. A similar result is achieved when limit switches are defined as high signals, using the LH command.

Can the velocity and acceleration values be converted to standard engineering units, such as mm per second?   There is no direct method for doing so on-board. A host program is normally used for this type of function.

How small can the controller be made?   The smallest full-featured servo control we have developed was less than one square inch in area. It is possible to compress the size even further, depending on the requirements.

Can the controller work from battery power?   Yes. However, the encoder power requirements represent a significant load that cannot be reduced under normal conditions. The motor power requirements can be the largest load. If a requirement to operate on battery power exists, please contact Diva Automation.

Can the controller work from USB power?   Yes. The USB is supposed to supply up to 500 mA for peripheral operation. Diva controllers typically require less than 100 mA, including the encoder, but not including the motor. Many of the motors used with Diva controllers will operate satisfactorily under normal conditions with USB power. It is also possible to connect to a second USB port for additional power.

Can the controller work from solar cell power?   Yes. See the discussions above. If a requirement to operate on solar power exists, please contact Diva Automation.

Does the controller have a "sleep mode"?   Diva controllers do not provide a standard sleep mode, however, the microcontrollers we use offer such modes. If a requirement for a sleep mode exists, please contact Diva Automation.

Does the controller have a low power mode?   Diva controllers do not provide a standard low power mode, however, the microcontrollers we use offer such modes. If a requirement for a sleep mode exists, please contact Diva Automation.

Does the controller have a "slave" mode for driving multiple axes?   Although some previous Diva controllers provided a slave mode of operation, none of our current products do so.

Does the controller support electronic gearing for multiple axes?   Although some previous Diva controllers provided electronic gearing, none of our current products do so.

How difficult is it to set up the servo loop PID gains?   The procedure for choosing the optimum values for the PID gains is too involved for this discussion, but the actual setting up is done with the DP, DI and DD commands. When the values have been calculated, these commands are used to enter them. If they are to be the normal values to be applied at power up, then the UD command can be used to update the non-volatile memory storage.

How can I integrate this controller into my high level language system program?   Diva controllers require that the high level language write strings of ASCII data to the serial port to which they are connected, as if an operator were entering them manually.

Can I use the brushless motor Hall sensors as position feedback in place of an encoder?   The Hall effect sensors used for commutation sensing in brushless motors are designed to provide a three-channel sequence, spaced at 60 degrees. Incremental encoders provide two channels of information, spaced at 90 degrees. In order to make use of the Hall signals for positioning, they must be converted to simulated encoder signals. This can be done using the Diva DA2020 chip.

Can this controller drive stepper motors?   Diva does not currently offer a stepper motor controller as a standard product. Please contact us if you have a stepper motor requirement.

Can this controller drive stepper motors in closed loop mode with encoder feedback?   Diva does not currently offer a stepper motor controller as a standard product. However, we do have a closed loop stepper controller in active development. Please contact us if you have a stepper motor requirement.

Can the output signals drive LEDs directly?   Yes. The typical LEDs used for status display can be driven without external drivers.

How do I connect a local position display?   Some Diva controllers provide a dedicated connector for LCD position display. Others can be connected using our application notes.

Can the controller accept controls through a PC-compatible keyboard?   Some Diva controllers provide a dedicated connector for PC-compatible keyboards. Others can be connected using our application notes.

Can this controller drive an LCD directly?   Yes. See above.

Can I use an external drive amplifier for larger motors?   Yes. Diva offers both analog and PWM external amplifiers for those controllers with insufficient on-board drive. Applications requiring more power than is supplied by our largest models may use any commercially available drive amplifier.

Can I use a remotely mounted motor drive amplifier?   Yes. In fact, Diva strongly recommends that the drive amplifier be located as close as physically possible to the motor, to reduce EMI and other problems.

Support

How soon can I expect an answer to a support problem?   Diva regards product support as the highest company priority. We realize that our continued success relies on the level of support we provide. We answer all support questions as quickly as possible, usually within 12 hours, depending on time zone differences. My limit switches don't stop the motor.   If this is an initial installation, it is possible that the limit switches are reversed. Try activating the negative limit switch while moving in the positive direction. If the motor stops, then reverse the wiring from the limit switches. Otherwise, make sure that limit switches are enabled by using the LN command to turn limit switch protection on. If problems remain, try activating the limit switches manually while reading the state with the TS command.

My motor is stuck. How can I unstick it?   A common problem when using motor driven micrometers is that the micrometer can be driven to the end of travel and more torque is required to reverse direction than was required to reach this point. Under those conditions, it may be necessary to physically reverse the travel, but this is not always possible without special tools, requiring a return of the product to the factory. Before taking this step, it may be worthwhile to disconnect the controller and supply a higher current to the motor from an external source.

Does Diva offer local support in my country?   Diva maintains offices in the U.S., as well as in Europe. Nearly all support requirements can be satisfied through e-mail and telephone contact. Occasionally, it is necessary to return a controller to us for repair.

How can I get support?   The best method to begin is through e-mail or our on-line FAQs to see if someone else has encountered a similar problem.

Do you offer on-site training?   Diva is happy to provide a quotation for on-site training as required. Qualified OEMs can expect to receive training at no cost other than reimbursement for travel expenses.

Do you offer factory training?   Yes, when required and appropriate.

Created on ... September 08, 2007