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SCPI Commands for the Digital to Analog Converter
VX4101A MultiPaq Instrument User Manual
3–195
BUFFer command prior to each utilization of the host’s FDC drivers to transfer
data back from the servant to the host.
The buffer length is specified in number of DAC samples. Note that all 8 DAC
channels are always transferred in any FDC transaction. Thus, a BUFFer setting
of 1 will return 16 bytes (8 channels, 2 bytes per channel).
The channel number parameter is the logical FDC channel number for the
instrument.
Note that this command is not necessary for measurement instruments, such as
the DMM or counter, since a measurement instrument knows how much data it
has ready to transfer via FDC. Nor is this command necessary for FDC writes to
a source instrument, since the host knows how much data will be transferred.
Thus, this command is only needed when the controller is utilizing FDC to
retrieve data from a source instrument.
See also FDC Operation in Instrument Functions
VXI[:SERVant]:FDC?
This query returns comma separated list of physical FDC channel numbers
allocated to the instrument. Physical and logical channel numbers have a 1 to 1
correspondence. Channel assignment occurs as follows:
Logical channel 1 is established on the first physical channel number
returned by the query.
Logical channel 2 is established on the second physical channel number
returned by the query. This process continues until all logical channels are
established on their corresponding channel number.
Physical FDC channel allocation is dependent upon the VX4101A option
configuration. Knowledge of a logical FDC channel’s physical identity is
required by users writing their own low level Commander-side FDC drivers for
their host computer. For more information, see FDC Operation in Instrument
Functions
VXI[:SERVant]:FDC:CONFiguration? [<channel number>]
This query returns the configuration state of the selected FDC channel. If the
optional channel number is omitted, the channel referenced by the
VXI:FDC:SEL command is used. Return values are the following quoted ASCII
strings:
“CLOSED”, “OPEN”, “INITIALIZED”, “READ ONLY”, “WRITE ONLY”,
“READ_WRITE”
Configuration states of READ ONLY, WRITE ONLY and READ WRITE imply
an OPENED and INITIALIZED state. A channel that is in a Closed state must
Query Response