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VME (VXI data transfer) Bus transfers
When data is transferred over the VME bus directly from the A/D converter, a read
of VME A24 address space, offset 12 (0C
16
), causes a measurement to be taken and
transferred all in the same read cycle. During the read cycle, the
HP E1429 takes a reading and puts the data into the register before the read cycle
completes. The ARM sources may be set to any legal source for this mode, but
TRIGger:START:SOURce must be set to VME. Selections can be made using the
VINStrument:CONFigure:VME:FEED command such that a single read produces
data from only one channel (16 bits), or both channels simultaneously (32 bits).
When the data is transferred post measurement, completion of the
INITiate:IMMediate command will automatically configure for a VME transfer
from memory, based on the settings of the VINStrument:VME:FEED command.
When the measurement has completed and the VME transfer has been set up by the
HP E1429, bit 1 (Memory Read Enable) of the A24 memory control register (base +
21
16
) will go high (1). At this point, data transfer can be initiated by the receiver by
reading the A24 data register (base + 0C
16
). Again, the VINStrument:VME:FEED
command is used to specify whether a single read will produce one channel (16 bits)
of data, or two channels (32 bits) of data. The
VINStrument:VME:MEMory:INITiate command will also configure for a post
measurement VME data transfer, but it need not be sent unless it is desirable to read
the same data multiple times.
Subsystem
Syntax
VINStrument
[:CONFigure]
:LBUS
:FEED <
source
>
:MEMory
:INITiate [no query]
[:MODE] <
mode
>
:RESet [no query]
:SEND
:POINts <
count
>
:AUTO <
mode
>
:TEST
:DATA <
voltage_list
> [no query]
:VME
:FEED <
source
>
:MEMory
:INITiate [no query]
[:MODE] <
mode
>
:SEND
:ADDRess
:DATA? [query only]
:IDENtity?
284 Command Reference VINStrument Subsystem