Freelance Modbus RTU unable to communicate
Hi, currently i am facing the problem of my Modbus RTU unable to communicate with FI820. Seperate from the previous question, this is another new RTU (RS-485) connection to a new controller in new location.
My modbus RTU (RS-485) Cable is a multi-drop cable the client is using this 1 cable to link to multiple devices of different slave IDs for Modbus.
I terminated the cable TxRx+ to TB870F point 20 & TxRx- to TB870F point 21, but still i am unable to get connection but when we used a connector to link to modbus simulator in my laptop the data is reading. Do I need to set any jumper in the FI820 card for RS-485 connection and also the TB870F card do i need to set anything? My controller is a redundant controller.
please have a look at the Mounting&Installation Manual for AC 800F, Chapter 4 Cabeling the AC 800F.
You need to make sure that the internal termination of the FI 820 (Jumper) is switched off. Below picture shows the location of the jumpers. Remove them all to switch off internal termination.
Then the cabeling and termination for a redundant Station should look like below:
using the external termination on TK 870 like below: