Keithley 2182 User Manual page 202

11-28 Remote Operation
Flow control (signal handshaking)
Signal handshaking between the controller and the instrument allows the two devices to
communicate to each other regarding being ready or not ready to receive data. The Model 2182
does not support hardware handshaking (flow control).
Software flow control is in the form of X__ON and X__OFF characters and is enabled when
XonXoFF is selected from the RS232 FLOW menu. When the input queue of the Model 2182
becomes more than 3/4 full, the instrument issues an X_OFF command. The control program
should respond to this and stop sending characters until the Model 2182 issues the X_ON, which
it will do once its input buffer has dropped below half-full. The Model 2182 recognizes X_ON
and X_OFF sent from the controller. An X_OFF will cause the Model 2182 to stop outputting
characters until it sees an X_ON. Incoming commands are processed after the <CR> character
is received from the controller.
NOTE
If NONE is the selected flow control, then there will be no signal handshaking between the
controller and the Model 2182. Data will be lost if transmitted before the receiving device is
ready.
Terminator
The Model 2182 can be configured to terminate each program message that it transmits to the
controller with any of the following combinations of <CR> and <LF>:
•
•
•
•
For RS-232 operation, *OPC or *OPC? should be used with slow responding
commands. A list of the slowest responding commands and details on *OPC and
*OPC? are provided in
LF line feed
CR carriage return
LFCR line feed, carriage return
CRLF carriage return, line feed
Section 12.