I/O Modules - Communication - Problem with communication in Modbus or BACnet over RS and IP

This article refers to multiprotocol I/O modules and SfAR series Modbus modules.

Issue

There is no communication between modules and controllers using any protocol (Modbus RTU/ASCII, Modbus TCP/IP, BACnet MS/TP or BACnet IP) .

Check if the wiring is correct.
Check if there are no devices nearby that could cause interferences.
Check if a proper protocol is set on the DIP switch.
Check if a proper Modbus/BACnet address is set on the module.
Restore factory setting using the 6^th DIP switch.
Update the firmware to the latest version. If the latest firmware has already been uploaded, reload it.
Check if the communication parameters are compliant between the module and controller.
Decrease the baud rate.
Increase the polling time on the supervising controller or set the points to the slower mode.
If the communication is in fact carried out from time to time, using a terminal, e.g., YAT, check if sent frames are correct or do they contain errors.
If the communication is carried out but the queried registers do not respond, check the registers' addresses for compliance with the documentation. Also, check if the length and number of registers to be read do not exceed the number of registers in the device. For example, the SfAR-8AO module contains 76 registers, so a program trying to read 100 registers reports an error. Decrease the length of registers.
If using SfAR-S-ETH, check if devices will communicate with the 3^rd an 4^th DIP switches set to ON on the ETH module.