Vaisala PTB330 - Manual (Page 66)

USER'S GUIDE____________________________________________________________________
64 __________________________________________________________________ M210855EN-D
Serial Line Communication
Connect the serial interface by using either the user port or the service
port.
For setting up a permanent interface to the host system, use the user
port. You can change the serial settings and operate in RUN, STOP
and POLL modes.
For temporary RS-232 connections, use the service port. Service port
is always available with fixed serial settings and, after power-up, it
always starts in the STOP mode.
Figure 36 Service Port Connector and User Port Terminal on
Motherboard
Numbers refer to Figure 36 above:
1 = Service port connector
2 = User port terminals