The Setra SRH300M3N105SSMXXX is a factory-configured Setra Model SRH300 humidity and temperature transmitter, set up as a duct-mount unit without display, one sensor port, and a 50mm integrated probe, running on Modbus RTU digital output. Besides measuring relative humidity and temperature directly, the SRH300 also calculates related values like dew point, absolute humidity, and mixing ratio, so you don’t need a separate calculation step on the controller side.
In actual application, since this unit communicates over RS485 Modbus RTU rather than a straight analog signal, you can run up to 32 SRH300 units on one bus, which is useful if you’re monitoring several duct locations from one controller. The housing is rated IP65/NEMA4, so it holds up well in mechanical rooms and duct environments.
Setra also offers optional configuration accessories (SETRAPCA1 and SETRAPCA3) that let you set custom output scaling or do a one or two point field adjustment of the RH and temperature reading, which is handy if you need to recalibrate on site without sending the unit back.
Before we quote this, we would normally check your BMS’s Modbus register map compatibility, the duct depth against the 50mm probe length, the accuracy class you need, and confirm the baud rate and parity settings your network uses. Hope this helps.
