Bausch Datacom DinBox RTU M4 Reference Manual page 40

5.4 Modbus mapping configuration
The DinBox RTU M4
device has to be connected onto the 2-wire RS485 interface. The asynchronous
parameter are configurable via the Configuration-Modbus-General page.
Modbus communication between a master and a slave is working with serial requests
and responses over the RS485 interface. When the RTU (Modbus master) receives no
responds or a responds with a bad CRC the request will be retransmitted. This will be
done x times (configurable between 1 and 10) as configured in Configuration-
Modbus-General page. When the responds stays incorrect after the x retries, the
received object value will be send to the IEC60870-5-104 master with a INVALID flag.
Simultaneously the RTU will send an "IOA Modbus failed" - TI30 ASDU with value 1 to
inform the IEC60870-5-104 master that there was a Modbus problem.
This value will go back to 0 when the RTU establishes again a good Modbus
communication OR when the RTU receives a "IOA clear Modbus failed" - TI58
command ASDU with value 1. Both will reset the "IOA Modbus failed".
5.4.1 Defining the configuration
Defining the mapping configuration must be done through a spreadsheet, in either
Microsoft excel or OpenOffice.
There are two tabs that hold configurations:
• Modbus configuration
•
IEC60870-5-104 configuration
The items for the Modbus master can be configured in the "Modbus configuration" tab.
has a build-in Modbus <> IEC60870-5-104 mapping. The Modbus