MODBUS Servo Drive Control

[themadgreek]

Hi,

This post is the further part of a thread I last posted (https://forums.ni.com/t5/LabVIEW/MODBUS-RTU-Communication-with-a-VFD-Sure-Servo-by-Automation/m-p/42...

I was able to establish communication with the servo drive and so i started to do the actual VI for the project i am intending to do. So what i primarily want to do is to JOG the motor up and down. The servo drive has a software that can do this, but i want to implement this via LabVIEW as there is further parts to this project. Once i connect my laptop to the system i can see that its communicating with the servo drive as the Rx and Tx indicators flash while running and my basic read program does work too.

The VI i made for JOG control does not seem to be doing anything, but again the Rx and Tx indicators flash while running, so i guess its trying to communicate. I am attaching the VI here for corrections and recommendations to be pointed out. I am also attaching the user manual references related with the operations required.

I know the steps i want to perform this are 

1. turn Servo ON

2. read device status (to know if servo is turned ON or not)

3. Set motor rpm

4. initiate JOG control (Forward/Reverse)

I am not sure if the addressing i use is the correct format or not. Also i am using MODBUS API library functions as the servo drive has Modbus RTU COMM enabled via RS-485. Please provide any corrections or thoughts. Looking forward to have this sorted out.

Thanks,

themadgreek

   

 

[Walker34]

I'm not familiar with Modbus RTU but I think your adress is maybe not correct. Try to use adress without "40000", and maybe with -1 value change.

Example:

try use 00035 and not 41035.

Or try to use 00034 and not 41035.

The issue is due to a conventional difference in documentations :

https://www.csimn.com/CSI_pages/Modbus101.html#:~:text=and%20the%20application.-,Modbus,-%3A%20When%...

See a moxa documentation that illustrates this, You can see difference between adress and register :

[themadgreek]

Hi,

So I tried communicating using the HEX address, and one of the steps i was attempting to do works, while the rest does not. In this case my first step is to 'Set Servo ON', i.e. to write a 1 to parameter P2.030. so i used the HEX address 023CH converted it to decimal 572 and used it in the VI and the servo turned ON.

I tried similar manner with the rest of the steps and none of those seem to work.

Also @Walker34 i tried what you said and that didn't seem to work either.

Any suggestions and insights to this would be really helpful.

Thanks,

themadgreek

[themadgreek]

Hoping I could get some help for the MODBUS comm problem. I was able to perform the first step or operation of what was required of the Servo Drive Control project, which is to turn the servo ON/OFF. But the rest of the steps doesn't seem to work for me. I would really appreciate any help and suggestions to help solve this problem. I am attaching the VI here to give clarification on possible questions.

Thanks.

Regards,

themadgreek