HP 53181A Programming Manual page 248

Commands Reference
:SYSTem Subsystem
:SYSTem Subsystem
This subsystem collects together the capabilities that are not related to instrument
performance.
:SYSTem:COMMunicate Subtree
The :SYSTem:COMMunicate subtree collects together the configuration of the
control/communication interfaces.
The :SYSTem:COMMunicate:SERial subtree controls the physical configuration of
the RS-232C port. Any command to change the settings takes effect immediately
upon receipt of the "program message termination." These settings are stored in
non-volatile memory, and are unaffected by power-on, save/recall, and *RST.
The :SYSTem:COMMunicate:SERial:TRANsmit subtree controls parameters
associated with transmission.
The Counter will always use one start bit and one stop bit.
:SYSTem:COMMunicate:SERial:CONTrol:DTR IBFull | ON | LIMit
Sets or queries the hardware pacing scheme.
The ON parameter (which is equivalent to DTR: HIGH in the
front-panel Utility menu) indicates that the DTR (Data Terminal Ready) line, which
is pin 4 of the RS-232 connector , is always asserted
(HIGH) to always be ready to allow data to be sent to the printer. Choose the ON
parameter when the printer or cable you are using does not support handshaking.
The IBFull parameter (which is equivalent to DTR: HW PACE in the front-panel
Utility menu) sets the RS-232 DTR line to indicate when the device is ready to
receive. When the number of received bytes in the input buffer of the Counter
reaches a stop threshold the Counter will de-assert the DTR line. When the number
of bytes has been reduced to a start threshold, the Counter will assert DTR,
indicating that it can receive input again. The Counter will also monitor the state of
the DSR (Data Set Ready) line, which is pin 6 of the RS-232 connector, and will
stop transmission if either of those lines becomes de-asserted. Choose the IBFull
parameter when the printer and cable you are using require handshaking for
counter-to-printer communication.
The LIMit parameter (which is equivalent to DTR: LIMIT in the
front-panel Utility menu) indicates that the RS-232 DTR line will be used to
indicate out of limit. The LIMit parameter will force the DTR line HIGH if the
measurement is in limit, and LOW if the measurement is out of limit.
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