Registers and coils addressing compatibility

Hello all,

I'm fairly new to ModBus and to communication protocols generally, so please be patient with me.

I have a production line where ModBus RTU is the communication protocol used between Omron PLC and Omron inverters. One of these inverters has a defective control board which can't be repaired.

The defective inverter is no longer available as its' production was discontinued. I tried to swap the defective inverter with another Omron inverter (other model) but there was a communication problem. I tried LS and Delta inverters too, but with no success.

After some research I found that the registers and coils addresses used for storing different variables such as the inverter status, or the run command differ from one inverter to another, for example:

Omron MX2 inverter uses address 0011h for ready signal, and Omron JX inverter uses 0010h for ready signal.

Is there any way to change the address of the ready signal and other coils and register addresses or any other solution to replace the defective inverter ??

Thank you in advance.
 
The VFD drive is a Modbus slave/server. The register addressing for the vast majority of field device Modbus slave/servers is done at the factory and the table/map is published for all to see and use. Some Modbus slave/servers have custom assignable Modbus registers. Most PLC's fall into this category because the data a PLC deals is a total unknown to the factory so the factory can not publish a table or map for a custom programmed PLC. So, there is almost no likelihood that your drive has assignable Modbus address registers.

However, whatever Modbus Master/Client that is communicating to the drive (a PLC?), can have its master/client program reprogrammed to deal with the replacement drive's different register address map/table. All Modbus Master/Clients are custom programmed to read or write whatever data is necessary for the application so there is 100% likelihood that if you can access the PLC program (not locked out with a password) and you have the appropriate development software that the master/client program can be reprogrammed.
 
Hi David_2,

Unfortunately I don't have access to the program of the PLC, and even if I did this means that I have to replace 18 VFDs to match the new addresses.
 
If you aren't 'locked out' but lack the programming resources to access the program, then considering hiring a systems integrator who can modify the program for you.

The other drives do not have to be replaced; the programming for them remains the same as it is now. Only the programming for oddball drive needs to change.
 
If you aren't 'locked out' but lack the programming resources to access the program, then considering hiring a systems integrator who can modify the program for you.

The other drives do not have to be replaced; the programming for them remains the same as it is now. Only the programming for oddball drive needs to change.
I can't access the PLC, it's password protected.
 
Another solution would be to use a gateway between your PLC and the new inverter. The gateway would be configured to emulate the old inverter and present the same registers/coils to the PLC. The gateway would translate the registers/coils to the appropriate registers/coils for the new inverter.

ICC's Mirius gateway can perform this conversion. If you would like assistance configuring the gateway for your application, you can submit a support ticket on ICC's website and a product specialist can assist you in creating a configuration.
 
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