Mitsubishi FX1N (with FX1N-485-BD card) and Delta VFD - Modbus?

[Jim_cz]

Hello guys,

I have to admit I'm still kind of a layman in this field but I'm trying hard to pick up some knowledge.

I have a PLC FX1N with the aforementioned card that sets a speed of a Delta VFD. I need to change the VFD for another brand and now I'm trying to figure out what kind of changes I'll have to do in the PLC program to get it work.

The manual for the PLC card doesn't mention the capability of modbus protocol, that's why I'm actually confused what I should be looking for.

However, in the PLC program I found some code converting data to ASCII starting with "colon, then something that could be the drive address, then 06 which should be function "write" etc.

Can someone help me how I can understand it (is it Modbus or not) and just outlined if after changing the VSD I'll have to modify the PLC program?

 

[raffles]

Post the model number of the Drive and the copy of the PLC program

It sounds like you are on the right path though. You will need the manual of the drive you are replacing, and have to modify the modbus reads and writes to match the new VFD. What drive are you replacing it with

 

[Jim_cz]

The "new" VSD I want to useis ABB ACS350-03E, I bought a modbus adapter for it.

The old VSD I want to replace is: delta VFD022B23B

The Mitsu PLC code that I think takes care of the speed setting of the old VSD is in the picture. D950 is what the PLC reads from the HMI.

 

[Jim_cz]

This is the Mitsu program, I think the VSD part start at 909

 

[raffles]

Step 869 is the RS instruction which writes the command to the serial port

Before that at step 859 and 864 which are calls to subroutines that actually build the command string used by the RS instruction

P4 builds the 16#06 command (single write) and the data address is set to 16#2001 - running frequency, with the data from D950 modified as the data content. It's pretty straightforward to follow through.

I didn't trace through P5 but it is probably a stop command. There are better ways of doing this rather than just setting the frequency and nothing else but that is a separate

Reference the Delta VFD Manual here http://www.deltaacdrives.com/wp-content/uploads/2012/06/VFD-B-User-Manual.pdf

You will have to modify the command strings to suit the new drive

Note that the RS instruction receives a response back from the drive and puts that in D1050 - I haven't looked to see if that is analyzed like it should be for a successful command

 

[Jim_cz]

Thanks a lot for your help. I really appreciate it.