3152A User Manual
Using The Instrument 3-34
Racal Instruments
©
2001
Selecting Binary
Download Forma
Binary data is sent to the Model in either 12-bit or 16-bit binary
format. When NORMal 12-bit downloads are used, the 3152A
calculates the start, stop and sync bits stored in memory in the
same data word as the 12-bit waveform points. When USER
16-bit downloads are used, the 3152A allows the user to
download waveform data AND start, stop and sync bit
information. This mode should be used with caution since an
incorrect download can cause unexpected operation of the
3152A. It also can allow the user to create custom sync pulse
patterns. See
Loading Arbitrary Waveforms
for more
information on waveform formats.
The download mode is selected using the following command:
WAVEform {NORMal | USER}
The default is NORM. This command is applicable only for
binary block transfers
The query:
FORMat:WAVEform?
queries the waveform download format and returns either
"NORM" or "USER."
Using Shared
Memory
Shared memory transfer is the fastest way to get waveforms
into the Model 3152A. In shared memory mode, the Model
3152A's CPU disconnects from the waveform memory and
passes access to the VXIbus. The internal data bus is
connected directly to the VXIbus, and data is downloaded into
the memory in binary blocks using A24 memory space. Byte
and bit order are the same as with the Arbitrary Block transfers
as shown in
Figures 3-1
and
3-2
. After the data is loaded into
the Model 3152A, control is returned to the instrument.
In shared memory mode, the Model 3152A’s memory acts
similar to Direct Memory Access (DMA). The instrument has to
be told when to receive data, send data, surrender control or
gain control. The Model 3152A has an auto-increment address
counter. The Slot 0 Controller need only select the base
address for both write and read cycles. Shared Memory
commands are explained below.
To write to or read from a segment, the user must first define
the segment using the command TRACe:DEFine. The trace
must then be selected using the command TRACe:SELect.
Refer to Loading Arbitrary Waveforms for more information.