Filter
Top Products
About Fast Data Channel (FDC) Operation
2–16
VX4101A MultiPaq Instrument User Manual
When your application program completes its FDC data transfer, you must close
the FDC channel to recover the system resources required to maintain the
channel, as well as to put the I/O connection in an appropriate state to re-estab-
lish a channel for the next FDC transfer.
This activity terminates the I/O session between the VXIbus instruments and
releases the I/O driver’s system resources.
FDC Operation with the DMM and DAC
The VX4101A MultiPaqtInstrument uses FDC protocol only with the Digital
Multimeter (DMM) and the Digital to Analog Converter (DAC). The DMM is a
measurement device and generates data that is transferred back to the host. The
DAC is a source device and accepts data from the host. The DAC can also be
programmed to return data back to the host.
The VX4101A FDC incorporates both physical and logical channels. The FDC
I/O drivers on the host and instrument device communicate with each other via
the physical FDC channel established between them.
Depending on the host application and the instrument configuration, you should
refer to the FDC channel in your application program with a logical channel
number. The logical channel number should always be the same for each
instrument that employs FDC.
Each instrument’s logical FDC channel numbers range from 1 to the number of
FDC channels used by the instrument.
NOTE. Since the DMM and DAC each only support one FDC channel, their
logical FDC channel number is always 1.
To support the logical channel, however, your application software must retrieve
configuration information from the Servant device channel to supply to the
Host’s FDC drivers prior to using the FDC channel.
The VX4101A supports the FDC protocol with the VXI:FDC SCPI Subsystem.
The following commands comprise the FDC command set:
VXI[:SERVant]:FDC?
Returns comma separated list of physical FDC channel numbers assigned to
the VX4101A.
VXI[:SERVant]:FDC:SEL [<channel number>]
Closing the FDC Channel
Terminating the
Instrument Session
About Physical and
Logical Channels
FDC SCPI Commands