National Instruments GPIB-232CV, Руководство пользователя

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Chapter 3 Operation
© National Instruments Corp. 3-5 GPIB-232CV User Manual
was intended for another device). This configuration could be used to
monitor all GPIB data bus activity. Notice that when the GPIB-232CV is
configured as a listen-only device, it may not be serial polled.
Special Conditions in D Mode
If the GPIB-232CV receives the universal Device Clear (DCL) command or
its listen address and the Selected Device Clear (SDC) command, the
GPIB-232CV will clear its internal data buffers and reset to its power-up
state. Neither Trigger nor Go To Local has any effect on the GPIB-232CV.
In D mode operation, the GPIB-232CV does not assert EOI when sending
characters along to the GPIB. You can use bit 1 of the serial poll response
byte to determine if there are characters waiting to be sent to the GPIB.
C Mode Operation
In C mode, the GPIB-232CV acts as the GPIB System Controller and
asserts IFC* for 500
µ
s when the GPIB-232CV is powered on. The action
of asserting IFC* for at least 100
µ
s initializes the GPIB and makes the
System Controller Controller-In-Charge (CIC). After the GPIB-232CV
becomes CIC, it sends out the GPIB listen address on U22 switches 4
through 8. If all address configuration switches are ON, no addressing will
be performed. This is useful if you are talking to a listen-only device that
does not require addressing. The GPIB-232CV will always assert REN*
when addressing other devices.
All incoming serial data to the GPIB-232CV is stored in an internal data
buffer until it is accepted by the GPIB device. All GPIB data sent to the
GPIB-232CV is passed immediately to the serial port without being
buffered.
Modes of Operation within C Mode
Four different modes of operation within C mode define how the GPIB
device is to be addressed—time termination, <CR> termination, <LF>
termination, and no-swap. In all modes, the GPIB device is addressed to
listen after the GPIB-232CV becomes CIC and all data received via the
serial port is buffered. The data is then passed along to the GPIB device.
The four modes of operation define at what point the GPIB device needs to