Connecting Mitsubishi PLC to Inverter Using MODBUS


Thread Starter

Essimseytov Asset

Good time of the day.

I'm interested if it possible to connect Mitsubishi FX3U with frequency inverter from a different company (INVT in particular) via Modbus RTU? And if it is possible, how should I configure it within PLC's program with GX IEC Developer?

Hoping for you to response.
One reason Modbus is so widespread is that is a protocol that is not vendor-specific; that is, products from different vendors can communicate using the Modbus protocol.

Both devices need to be capable of using Modbus, which sometimes is an option, firmware and/or hardware.

Both devices need to use the same hardware layer (the wiring and electrical standard) for communication.

The Modbus RTU is a 'serial' protocol, typically for point-to-point over short distances using RS-232 or over longer distances using multidrop RS-485. Modbus/TCP uses Ethernet.

There are commercial gateway/converter/servers that convert from RS-232/485 in case one device uses serial and the other Ethernet.

Drives are always slave/servers, the PLC has to be a Master/client.

In terms of programming, most vendors have some tutorial or examples for Modbus.

My suggestion is to use a generic Modbus master (Modscan32, Simply Modbus, ModPoll, a dozen others) that runs on Windows box to make the connection to the drive in order to establish communications and understand how to read a register, then how to write a value to the drive.

With that background, tackle the PLC programming.

As to the specifics for your devices, that's what spec sheets and manuals are all about.