Salter Brecknell CP130 - Manual (Page 8)

CP130 User Guide Page 8 of 11
7 INTERFACE DETAILS
7.1 RS-232
SERIAL INTERFACE
The CP130 printer has an industry standard RS-232 interface. The default parameters are 9600
baud, 8 data bits, 1 stop bit and no parity. Other baud rates can be programmed by control codes, or
by using a setup utility available from the factory.
Serial data is expected in standard RS-232C format with -12V meaning 'mark' or '1' and +12V a
logical '0', with reference to the common ground. The serial data output line, TxD, transmits
XON/XOFF and status information to the host at the same Baud rate and in the same format as the
serial data input. The hardware busy line is true (nominal -12V) when busy. Both serial output lines
will relax to approximately 0V when the CP130 is off, and the user must allow a short period after
switching on before relying on the values of these signals.
Some host equipment uses a constant space condition (+12V) to indicate a reset condition or wait
state. Some battery powered host equipment present the same output signal when they go to sleep.
The CP130 can be set to ignore this condition as detailed in the Programmer’s Guide, but even then
this type of host behaviour may result in one or more spurious characters being received and printed.