> Can the 'X7' port (Port for connecting control panel or PC) in ABB-ACS850 VFD
> be used for interfacing with PLC through 'MODBUS TCP/IP' protocol...?
Not sure about 850's but some ABB drives use RJ-45's for RS232 serial to the keypad and PC. (Actually, using RJ-45's for serial is not extremely uncommon.)
If that's the case here, you won't be able to talk to it with Modbus/TCP because it's not an Ethernet port despite the connector. I believe the 850's are compatible with the R-series expansion cards, so why not just get a RETA-01?
I've doubted this, based on the RJ45 connector provided in the VFD. But, the cable used for programming the VFD from a PC has a RJ45 connector on one side & a SUB-D9 connector on another side.