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SCPI Commands for the Digital to Analog Converter
3–194
VX4101A MultiPaq Instrument User Manual
VXI[:SERVant]:FDC:CLOSe [<channel number>]
This command closes the selected logical FDC channel. If the optional channel
number is omitted, the channel referenced by the VXI:FDC:SEL command is
used. Closed FDC channels must be opened before they can be accessed for data
transfer. The channel number parameter is the logical FDC channel number for
the instrument.
VXI[:SERVant]:FDC:OPEN <channel mode>[,<channel number>]
This command opens the selected logical FDC channel. The mode parameter
determines the direction of data flow, read only, write only or both read & write.
The <channel mode> parameter can be one of the following unquoted SCPI
labels: RO, WO, RW. Interpretation of Read and Write is from the servant
device’s point of view.; Data is READ off the VXIbus back plane into the
instrument and WRITTEN from the instrument to the VXIbus back plane. If the
optional channel number is omitted, the channel referenced by the
VXI:FDC:SEL command is used. FDC channels must be opened before they can
be accessed for data transfer.
Each opened FDC channel consumes system resources. Bidirectional channels
require more resources than Read or Write only channels. Only open FDC
channels in the operational mode appropriate for their intended use.
If the DAC FDC channel is opened for both reading and writing (mode
parameter = RW) then the DAC can be loaded with ASCII data (see
TRACE|DATA command description) and read back in binary. (see the FOR-
MAT command description). You can then store the binary representation of the
TRACE data on your hard drive and subsequently reload it into the DAC as a
binary file using the FDC channel. This results in faster waveform loading
operation for the DAC.
VXI[:SERVant]:FDC:SEL <channel number>
The command selects the FDC logical channel to be used by subsequent FDC
commands. The channel number parameter is the logical FDC channel number
for the instrument. It is not necessarily related to the physical FDC channel. It is
not related to the DAC channels. All of the DAC channels use only one FDC
channel. The power up default is logical channel 1.
VXI[:SERVant]:FDC:BUFFer <buffer length>,[,<channel number>]
This command specifies the amount of data to transfer from the servant back to
the host during a FDC protocol data transfer; and, it configures the instrument
for the transfer. This command is only needed when the controller is reading data
back from a source instrument (a the source instrument typically accepts data
from the host (via the VXI backplane) and sources it to the UUT). This
command allows you to both define the size of the data to transfer in the reverse
direction back to the host and to signal the instrument hardware to present the
specified amount data to the FDC transfer mechanism. You must issue the
Description