PSM1700 PsimetriQ user manual
5-5
5.3 RS232 connections
The RS232 port on PsimetriQ uses the same pinout as a
standard 9 pin serial port on a PC or laptop (9-pin male ‘D’
type).
PsimetriQ will only transmit when CTS (pin 8) is asserted,
and can only receive if DCD (pin 1) is asserted. PsimetriQ
constantly asserts (+12V) DTR (pin 4) so this pin can be
connected to any unwanted modem control inputs to force
operation without handshaking. PsimetriQ has a weak pull
up on pin 1 as many null modem cables leave it open
circuit. In electrically noisy environments, this pin should
be driven or connected to pin 4.
To connect PsimetriQ to a PC, use a 9 pin female to 9 pin
female null modem cable: