Vaisala HMT330 - Manual (Page 81)

Chapter 4 _________________________________________________________________ Operation
VAISALA ________________________________________________________________________ 79
Serial Line Communication
Connect the serial interface by using either the User Port or the Service
Port.
For permanent interfacing to host system, use the User Port. You can
change the serial settings and operate in RUN, STOP, SEND, POLL, and
Modbus modes.
For temporary connections, use the Service Port. The Service Port is
always available with fixed serial settings.
0605-039
Figure 51 Service Port Connector and User Port Terminal on
Motherboard
The following numbers refer to Figure 51 above:
1 = Service port connector
2 = User port terminals