newbee question about LSD-KD

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jensvanhoof
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Joined: Tue Dec 15, 2015 4:03 am

newbee question about LSD-KD

Postby jensvanhoof » Tue Dec 15, 2015 4:42 am

Hi,

I've recently purchased a DGM60ARAK stepper motor with a LSD-KD driver with build-in controller. Also, I got the USB interface and MEXE02 software.
I can successfully turn the motor at different speeds in the two directions in the software. I am now looking for a way to eventually being able to give directional commands using the Arduino platform.

I'm new in stepper motors so obviously there is a whole lot to learn but this far I think I've understood:
-The driver (and motor) can be controlled through an RS-485 interface with the Modbus RTU protocol. (I don't know this yet but there seems to be a lot of information to read.. :-))
-In the build-in controller a number of presets can be programmed, for example with the MEXE02 software. Say, a preset at 90°, another at 180° and so on. With a Modbus RTU master, I should be able to give a command like 'go to preset 1' (90°).

I'd appreciate it if this could be confirmed by someone more knowledgeable than me :-).

In my application however, I would have to give a command to go to a specific position (for example again 90°), but this 90° might be 360° offset compared to the last time I gave the instruction for 90°, so a complete turn was added (and so the absolute position of the motor would be different. The motor could make hundreds of these turns, and so never return to the same absolute position, but obviously be in the same 'actual' position then it was before.

Let me clarify. Say I want to write a program to make the motor skip 90° to the right every 5 seconds:
S01: 0°
S05: 90°
S10: 180°
S15: 270°
S20: 360° (0°)
S25: 450° (90°)
S30: 540° (180°)
S35: 630° (270°)
S40: 720° (0°)
..and so on.

So it seems that presets are not the way to go, as I would have to write thousands of them.
What would be the better approach to do this? I'm very aware that I might be asking very stupid questions, but I don't really know where to start looking.

Any input would be greatly appreciated.
Thanks a lot,
Jens

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om_tech_support_JT
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Location: Torrance, CA
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Re: newbee question about LSD-KD

Postby om_tech_support_JT » Tue Dec 22, 2015 4:31 pm

Hi jensvanhoof,

First of all, thank you for your purchase. We are not quite familiar with integrating Arduino to our products yet but we are learning.

If you can use the MEXE02 software to set your stored data and parameters, there is no need to use Modbus RTU protocol. Modbus RTU is just another way you can set the data via RS-485 remotely or in real-time if you do not plan to use our MEXE02 software to set your data. The learning curve would be quicker if you already have working knowledge of hexadecimals and binary. Using the OPX-2A hand held module is another way you can set the data without our software.

You can use a combination of both MEXE02 and Modbus RTU data setting methods. For example, set all operation data and parameters with our MEXE02 software, then use your Arduino to to send Modbus RTU command messages to our driver via the RS-485 communication port just to control the remote inputs register. Once your data is set, all you need to execute motion is either direct or remote (RS-485) inputs. This combination method minimizes the number of wires necessary.

In your example, you are repeating the same motion over and over again. This is very simple to program. With our MEXE02 software, you can simply set an incremental move of 90 deg in Data 0 operation data with your speed parameters (POSITIONING MODE = INC). Then every time you turn on the START input either directly or remotely, it will execute the same Data 0 move from the current position. In any application requiring repeated motion, I would stick with incremental moves instead of absolute moves. I think this is the easiest way you can program what you want. You can try this in TEACHING/REMOTE OPERATION after all stored data has been programmed and written to the driver.

For repeated index operation such as yours, pay attention to the software limits. If you exceed the software limits, the driver will alarm and cease operation. Use Round setting to reset the counter at your preferred value. It's in the COORDINATES section of the software.

As far as the 5 second delay in between moves, we can set a DWELL time for each individual move, but only 4 can be linked at any one time (see LINKED MOTION). It may be easier to program the time delays on a PLC or Arduino which would control our START input either directly or remotely.

Please let us know if you have any more questions or need screen shots of the software.

jensvanhoof
Posts: 2
Joined: Tue Dec 15, 2015 4:03 am

Re: newbee question about LSD-KD

Postby jensvanhoof » Tue Mar 08, 2016 6:01 am

Hi,

Thanks for the reply -I had to let the project go for a while but have just started again.
I have put a few 'test lines' in the 'operation data' section in the MEXE02 software, to experiment with the incremental function combined with a specific position. This seems to work great.

In the final product however, no interface to the MEXE02 software can be used and I'll have to operate everything through the modbus protocol. In my last example, I gave examples in steps of 90°, but this could really be any number (say in steps of .5°). So I might have to tell "Increment by 17.5°" at one point, but also "increment by -160.5°" at another time. So basically 720 different possibilities.

Would the correct approach then be to:
a) setup operation data #0 with the desired position (for example #0 will now be 'incremental, position 1750, operation speed 50000, operating mode single,..etc)
b) tell the driver to execute operation data #0

rather then 'predefine' all presets in MEXE02?

Thanks!
Jens

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om_tech_support_JT
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Re: newbee question about LSD-KD

Postby om_tech_support_JT » Mon Mar 28, 2016 5:40 pm

Hi Jens,

With your LSD-KD driver, you are able to do what you want with your a)b) method. You can 1st program registers for position value, operating speed, accel/decel rates (and more) for a complete operation data set (indicated by operation data number), then use the 7Dh remote input command register with BCD values to turn on inputs remotely via Modbus RTU to start the motion. For example, to execute the Data 0 motion profile (after all related registers have been programmed), set 7Dh register to 8, which will turn on bit3 = START input (with default input assignments). START input with no M0~M5 inputs indicate that you want to execute Data 0. Then you can edit the Data 0 registers again before executing another input command to run a different motion profile. Remember to set the 7Dh register value to 0 before executing a different operation. Let me know if you need any more explanations of the above. I can refer you to specific pages in the user manual.

For your type of operation where position values are always changing, perhaps presetting all your stored data with our MEXE02 software is not the best idea. The above method would be what we recommend for the LSD-KD driver.

We have released a newer AZ series (similar to the DG/AR series but with solid shaft instead of hollow bore). The AZ series driver is able to store up to 256 positions as well as new program commands for looped or event jump operations. The AZ series also offers Direct Data Operation which allows you to both set and execute data by writing once to multiple registers. I think the Direct Data Operation of the AZ series would help you in this case, but it's a whole different motor and driver.

FYI the non-volatile memory for both AR/AZ series drivers can be rewritten approximately 100,000 times. This is if you perform any "NV Write" operations via Modbus RTU. This basically moves the RAM memory into non-volatile memory. Modbus RTU mainly works in RAM if you do not perform any NV Write operations. If you power cycle before doing an NV Write operation, then your newly written data will not be saved.

aldoned
Posts: 32
Joined: Mon Sep 14, 2015 3:03 am

Re: newbee question about LSD-KD

Postby aldoned » Wed Jun 22, 2016 1:41 pm

Thanks for the info


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