User Tools

Site Tools



Using the ComfileHMI as a Modbus RTU Slave

Typically, the ComfileHMI operates as a Modbus RTU master and queries an external device that is operating as a Modbus RTU slave. However, the ComfileHMI can also operate as a Modbus RTU slave, and respond to queries from a Modbus RTU master.

To enable the Modbus RTU slave, select the “MODBUS RTU SLAVE” via the serial port channel settings: [Project Properties > Communication Configuration > Add Channel] as follows:

When operating as a Modbus RTU slave, only the ComfileHMI's internal memory is addressable. Modbus address 0 corresponds to internal memory address 0, Modbus address 1 corresponds to internal memory address 1, etc. in a 1-to-1 mapping for the entire address range. Only 16-bit Modbus functions (e.g. Register reading and writing) are supported. If the user stores a value larger than 16-bits to the internal memory location, only the least significant 16-bits will be read from or written to through the Modbus RTU slave.

The ComfileHMI also supports slave communication over Ethernet, using the Modbus TCP protocol. See Modbus TCP.

Back to ComfileHMI

comfilehmi/hmi_connection_modbus_rtu_slave/index.txt · Last modified: 2020/03/01 16:04 by COMFILE Technology