[ Vfdmod ] An easy VFD control over MODBUS RTU

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4 years 9 months ago #231444 by Todd Zuercher
Replied by Todd Zuercher on topic [ Vfdmod ] An easy VFD control over MODBUS RTU
Double check that all com settings are the same for your device and in Linuxcnc. Make sure your device is configured for RTU and not ASCII.

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4 years 9 months ago #231800 by s_volenszki
Replied by s_volenszki on topic [ Vfdmod ] An easy VFD control over MODBUS RTU
Hi, thank you for your answer!

I had no time on the week just tonight and I fired up the logic analyser. The result was surprising, actually all response CRC are invalid checksum. I used Saleae Logic analyzer software with Modbus RTU analyzer. After I started to read the VFD documentation again and I found something:

"At the time of transmission, the low bytes are in CRC CHK high bit front and the high bytes are in the back. When CRC is added to the message, low bytes are added first, and then high bytes."

This is a command to read the VFD current frequency:
01 03 10 00 00 01 80 CA

This is the answer from the VFD:
01 03 00 02 09 C4 E3 C9

And if I calculate the 01 03 00 02 09 C4 CRC value:
CRC-16/MODBUS => 0xC9E3

So this is absolutely clear the VFD answering the CRC in reverse. Now only one question left, how can I reverse the CRC before the Vfdmod start to compare with the pre calculated CRC?

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4 years 9 months ago #231808 by Todd Zuercher
Replied by Todd Zuercher on topic [ Vfdmod ] An easy VFD control over MODBUS RTU
I would suggest checking your VFD's documentation for a setting that corrects it.

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4 years 9 months ago #231863 by aekhv
Replied by aekhv on topic [ Vfdmod ] An easy VFD control over MODBUS RTU
According file attached upper (see  forum.linuxcnc.org/24-hal-components/387...-rtu?start=70#230567 ), write function works well, including CRC checking.

vfdmod: setting command speed value to 2500 (0x09C4)...
[01][06][10][00][09][C4][8A][C9]
Waiting for a confirmation...
<01><06><10><00><09><C4><8A><C9> <<< OK! Response is valid!

vfdmod: setting control word value to 6 (0x0006)...
[01][06][20][00][00][06][02][08]
Waiting for a confirmation...
<01><06><20><00><00><06><02><08> <<< OK! Response is valid!

vfdmod: reading 'spindle.rpm-out' from address 4096 (0x1000)...
[01][03][10][00][00][01][80][CA]
Waiting for a confirmation...
<01><03><00><02><09>
ERROR CRC received 0x209 != CRC calculated 0x20F0

I can't believe CRC works normally in writing mode, but needs to swap a pair of bytes in reading mode. It's insane! :)

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4 years 9 months ago #231875 by s_volenszki
Replied by s_volenszki on topic [ Vfdmod ] An easy VFD control over MODBUS RTU
I just guess, If I give a write command, the VFD echoes back the command what I sent, and do not bother with the CRC calculation (except if it has an error). But when I read data, It must calculate CRC, because the responded data is not related to the request command. I upload the whole SKI-780 RS485 communication protocol documentation, the CRC verification section starts at page 15. If you have time to take a look on it, maybe you can spot on the solution.

I do not know what's next. I try to change Modbus data format and Modbus protocol type, if it will fail too, I think I either start to learn the 0-10V analog solution or the PWM solution (if the VFD supports), or ask may local supplier to give me quotation for a supported VFD (like Omron or Siemens).

Thank you all for your help so far.

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4 years 9 months ago #231886 by s_volenszki
Replied by s_volenszki on topic [ Vfdmod ] An easy VFD control over MODBUS RTU
Finally I did it :) I made a factory reset on the VFD and started over the settings.

What I did with Sako SKI-780:
  • Set the PP-01 to 01 manual on the VFD control panel (01 = reset factory settings except motor parameters)
  • I used the default 9600 baudrate.
  • Set the command source to RS485 with serial console app (01 06 F0 02 00 02 9A CB).
  • Set the main frequency source to RS485 with serial console app (01 06 F0 03 00 09 8A CC).
  • Changed the Modbus protocol to 31, standard Modbus communication, through RS485 with serial console app (01 06 FD 05 00 1F).
  • Changed the Modbus data format to 8,N,1 (value 3) through RS485 with serial console app (01 06 FD 01 00 03).
What is the most interesting, if I now debug LinuxCNC in terminal, I can see that the CRC Low and high bits are still in reverse order, but works. For example:

Read baudrate
Request: 01 03 FD 00 00 01 B5 A6
Response: 01 03 02 17 75 76 53
Calculated response CRC: 0x5376

Write baudrate
Request: 01 06 FD 00 17 75 76 71
Response: 01 06 FD 00 17 75 76 71
Calculated response CRC: 0x7176

Set spindle speed to 100Hz
Request: 01 06 10 00 09 C4 8A C9
Response: 01 06 10 00 09 C4 8A C9
Calculated response CRC: 0xC98A

So I don't know what was the key parameter for the solution, but now it works, and I hope, next time if someone walks the same way, will end up in less dead ends like me did (I think because of my inattention) :)

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4 years 9 months ago #231927 by hitchhiker
Replied by hitchhiker on topic [ Vfdmod ] An easy VFD control over MODBUS RTU
hi!

I want to work with your component but i think i am to stupid to do the correct changes to the ini......

i add the ini to this reply and a picture from the registers.

please please please help.... thanks...



 

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4 years 9 months ago #232149 by hitchhiker
Replied by hitchhiker on topic [ Vfdmod ] An easy VFD control over MODBUS RTU
hi...nobody has a toip,idea or could help me?!

thanks

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4 years 7 months ago #236664 by H2B
Replied by H2B on topic [ Vfdmod ] An easy VFD control over MODBUS RTU
I've successfully used this to control a Folinn BD600 over MODBUS, and it should also apply to other Folinn (Fuling) models of VFDs. Unfortunately this model requires a reverse command to be sent using a negative percentage to the relative frequency command, which is something I'll try to figure out at a later stage.

Thanks @aekhv for this lovely bit of code!

Hope this information comes in handy for anyone using a Folinn VFD! :D

Here's the ini file I've used on Debian Bullseye with LinuxCNC 2.9 (default release packages work perfectly fine):

Code:
[Common] MaxSpeedRPM=24000 MinSpeedRPM=6000 ;AtSpeedThreshold=0.05 [RS485] SlaveAddress=1 SerialDevice=/dev/ttyUSB1 BaudRate=9600 LoopDelay=500 ProtocolDelay=6 ;IsConnectedDelay=10 ConnectionErrorList=110 ConnectionDelay=500 [Control] Address=0x1000 RunForwardValue=0x0001 RunReverseValue=0x0002 FaultResetValue=0x0007 StopValue=0x0006 [SpindleRpmIn] FunctionCode=0x06 Address=0x3000 Multiplier=10000 Divider=24000 [SpindleRpmOut] Address=0x3001 Multiplier=30 Divider=10 [freq-running] FunctionCode=0x03 Address=0x3001 PinType=float PinName=freq-running Divider=10 [bus-voltage] FunctionCode=0x03 Address=0x3002 PinType=float PinName=bus-voltage [output-voltage] FunctionCode=0x03 Address=0x3003 PinType=float PinName=output-voltage [output-current] FunctionCode=0x03 Address=0x3004 PinType=float PinName=output-current Divider=100 [output-torque] FunctionCode=0x03 Address=0x3006 PinType=float PinName=output-torque [run-speed] FunctionCode=0x03 Address=0x3007 PinType=float PinName=run-speed [spindle-load-speed] FunctionCode=0x03 Address=0x300F PinType=float PinName=spindle-load-speed [power-on-time] FunctionCode=0x03 Address=0x301A PinType=float PinName=power-on-time [spindle-run-time] FunctionCode=0x03 Address=0x301B PinType=float PinName=spindle-run-time [fault-code] FunctionCode=0x03 Address=0x8000 PinType=float PinName=fault-code

And here's the files added to the custom.hal to make it work with the interface:
Code:
loadusr -W vfdmod bd600.ini --debug net spindle-vel-cmd-rpm => vfdmod.spindle.rpm-in net spindle-at-speed <= vfdmod.spindle.at-speed net spindle-cw => vfdmod.control.run-forward net spindle-ccw => vfdmod.control.run-reverse

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4 years 7 months ago #236676 by rodw
Replied by rodw on topic [ Vfdmod ] An easy VFD control over MODBUS RTU
Beautiful thanks. I had just about given up on using this with my Folin BD600
I got a feeling my RS485 interface is bad but you have inspired me to keep trying!
It would be helpful if you could outline the changes you made in the VFD settings to enable RS485 control

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