Autodesk AUTOCAD 2006, Command Reference Manual, Page: 931 / 1490

Flow Control
Sets the flow control for your plotter. The default flow control setting is
XON/XOFF (software handshaking) for compatibility with previous versions
of the program. If you select Hardware handshaking, you can specify
additional settings in the Advanced Settings for COM Port Dialog Box that
correspond to different pins on the RS232 connector.
Protocol
Displays the protocol settings available for your plotter. Use the protocol
recommended by your device manufacturer. For more information see the
documentation for your device.
Advanced Settings for COM Port Dialog Box
File menu: Plotter Manager
Command line: plottermanager
Specifies additional hardware handshaking settings for serial ports.
CTS
Enables Clear To Send handshaking. This monitors pin 5 of a 25-pin serial
port or pin 8 of a 9-pin serial port. CTS is an input bit, monitored for an output
from the plotter or printer.
DSR
Enables Data Set Ready handshaking. This monitors pin 6 of a 25-pin serial
port, or pin 6 of a 9-pin serial port. DSR is an input bit, monitored for an
output from the printer or plotter.
RLSD
Enables Received Line Signal Detector handshaking. This is sometimes called
DCD or Data Carrier Detect. It is an input pin that can be monitored for an
output from the plotter. It is on pin 8 of a 25-pin serial port and on pin 1 of
a 9-pin serial port.
RTS
Controls the Request To Send output bit. This sends a signal to the printer or
plotter on pin 4 of a 25-pin serial port or on pin 7 of a 9-pin serial port.
Disabled
Disables the RTS line when the device is opened.
Advanced Settings for COM Port Dialog Box | 907