Modbus RTU in 800xA v6.0.2 or CCB 6.0.0-1 or 6.0.0-2
I have a problem with the Modbus RTU interface in v6.0.2 of 800xA and with CCB 6.0.0-1 (PM866 Firmware 22.214.171.124) and CCB 6.0.0-2 (PM866 Firmware 126.96.36.199).
When I use CCB 5.1.1-2 this works perfect on the COM3 port and the CI853 ports. I am using a TK853 cable connected to the PM866 and via a serial cable to a USB-to-Serial converter. A Modbus simulator is used on the PC side as the slave device
On the master side (PM866) the CTS and RTS are bridged together and the DTR and DCD are bridged together. The TD and RD lines are swapped between the converter and the TK853. The 0V runs straight through.
Why would this not work on v6? I see there are 2 new entries in the v6 Modbus HW library that contains the Exception register address and Diagnostic register address, but everything else is the same.
I am still using the MBConnect function block, MBRead and pulse gen function blocks to cyclically read data, but I get Timeout status -4929 on the MBconnect in v6.
I have inserted a pic of the good comms in v5.1 (CCB 5.1.1-2):