Agilent Technologies L4400 - Manual (Page 225)

L4450A 64-Bit Digital I/O with Memory and Counter 8
L4400 User’s Guide 213
Start the capture. The SENSe:DIGital:MEMory:STARt command sets the
channel to begin the data capture. The capture begins when the handshake
occurs.
Check the status of the transfer. You can use the
SENSe:DIGital:MEMory:DATA:POINts? query to return the number of
samples currently in memory.
Retrieve the captured data. Set the desired memory retrieval format using
the
SENSe:DIGital:DATA:FORMat command. You can set the memory to be
read as either LIST or BLOCk . The LIST parameter (default) returns the
data as comma separated ASCII values. BLOCk returns the data in
IEEE- 488 block format.
Before you can read the data in memory, you must stop the memory
operations using the
SENSe:DIGital:MEMory:ENABle OFF command.
Read all the captured data using the SENSe:DIGital:MEMory:DATA:ALL?
query. This performs a non- destructive read of all data in the bank’s
memory.
To read specific captures, use the SENSe:DIGital:MEMory:DATA? form of
the command. This command takes index and count parameters to specify
which data to retrieve. The oldest data in memory has an index of ‘0’. The
count specifies the number of samples to read. count + index must be less
than the number of captured points.
Both these data reads are non- destructive to the bank memory. To clear
the memory for new data, send the
SENSe:DIGital:MEMory:CLEar
command.
Interrupt Lines
Each bank has an interrupt line that can be used with memory input or
output operations. When a bank is set to input data, the interrupt line is
an output. When a bank is set to output data, the interrupt line is set to
be an input. You can set the polarity of the interrupt line for input and
output operations using the
CONFigure:DIGital:INTerrupt:POLarity
command.
You can configure the interrupt line drive mode, output drive level, and
input threshold. These parameters are set for both the handshake lines
and interrupt line on a bank. See
page 204 for details about setting these
parameters.
Memory Output Operations
For memory output operations, the interrupt line is sensed and can be
used to start or stop memory output operations. This provides a hardware
means to control the data output.