IBM 1725 SLS - Manual (Page 56)

Communications
QMS 1725 SLS Print System User's Guide 2-22
Hardware Flow Control
Controls the flow of data between the printer and the host.
PS Protocol
Sets the binary communications protocol (BCP) for communicating
over a serial interface to a PostScript printer.
Menu Administration/Communications/Serial/Hdwe Flow Ctl
Choices DSR POL
DSR
DTR POL
DTR
RTS
CTS Normal, reverse
Off, on
Normal, reverse
Off, on
Off, on
Off, on
Defaults DSR POL
DSR
DTR POL
DTR
RTS
CTS Normal
Off
Normal
On
Off
Off
Notes If the host uses hardware flow control, set this option to match
the type used by the host.
However, to download printer system software to flash ROM
via the serial port, RTS and CTS must be set to On, and the
cable pinouts must be connected as shown in appendix B,
“Technical Specifications.”
Menu Administration/Communications/Serial/PS Protocol