Campbell Scientific HMP155A Temperature and Relative Humidity Probe - Manual (Page 42)

Appendix C. Interfacing with HMP155A RS-485 Output
Using HyperTerminal, send the following commands to the HMP155A:
VERS[enter] to get a response from the sensor; for example, HMP155A 1.26
SERI[enter] to get the current RS-485 settings; for example, 4800 E 7 1
SERI 9600 N 8 1[enter] to change the RS-485 settings; response should be
9600 N 8 1
R[enter] to put the sensor in the Run mode to output continuous measurements
Responses to the commands are shown in the screen capture below.
After the settings have been changed, change the baud rate in HyperTerminal
to 9600, and make sure the relative humidity and temperature string is being
displayed before connecting the sensor to the MD485.
C.3.1 MD485 Multidrop Interface Configuration
Using the Device Configuration Utility, configure the MD485 as shown below.
C-6