For setting up serial communication to the Mars Soiling Sensor via Modbus RTU, please use the following settings on your Modbus client:


  • Scan period  >= 1 second
  • Timeout >= 500 ms
  • Delay between polls >= 30 ms


Do not poll (scan) the unit more than once per second. Using shorter timeouts or higher polling rate may result in communication or timeout errors. 


NOTE: The parameters listed above are supported as of Mars firmware version  R5124 (May 2021). Older firmware versions required longer timeout settings of up to 3 seconds. For best performance, please update your Mars unit to the latest firmware. (See Mars Firmware Update.)


For a complete list of Mars Modbus registers and other Modbus setting information including supported baud rates and data formats, please see the Mars User Guide.