To configure M171O controller as modbus slave please refer the following steps:
1) Open the Somachine HVAC Application Software
2) Create New Programme with M171O with Modbus Slave Only.
3) Define Variables need to communicated in Status Variables and EEPROM variable of Modbus Parameters in Resource Tab of Project tree.
4) Configure the address of status and EEPROM variables in modbus master device.
5) Keep the serial setting parameters same as configured in modbus master in Somachine HVAC device software. These parameters are Modbus Address (C30), Baud Rate (C31) and Parity (C32) and located in configuration parameter of BIOS parameter tab.
6) Make Sure the connected device firmware is 412.XX. If 542.XX then click on the BIOS download option in HVAC device. Located the firmware file and select download. Power should not be connected to the M171O during the BIOS download.
7) Compile and download the code M171O.
Now connect modbus master to M171O RS485 port and check communication.