Having an issue setting up modbus communications between Mach4 and PLC. I can write multiple holding registers from Mach to the PLC but cannot read any.
I have Mach4 installed on a computer and connected to a compactlogix PLC via Prosoft MVI69-MNET card via ethernet
PC IP address 192.168.1.40
Mach 4 modbus configured for TCP, IP address 192.168.1.48
1) read register 50, 10 words long
2) write register 1, 10 words long
MNET IP 192.168.1.48 - read/write to IP address 192.168.1.40
1) writes to holding register 50, 10 words long
2) Reads holding register 1, 10 words long
In my PLC data table I can see signals from Mach4 eg. Axis enable bits, but when I set a bit in the PLC that would jog an axis, the bit is not seen in Mach.
If I run a modbus simulator on the computer I see data from both in the correct registers.
As a side note, if I change the Mach modbus configuration to IP address of the computer with the modbus simulator running, I get 2 way communications.
What is wrong with me setup? I should not need to run a simulator.
Thanks