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214 L4400 User’s Guide
8 L4450A 64-Bit Digital I/O with Memory and Counter
• STOP: The memory output is halted on the rising edge of the
interrupt line.
• GATE: The interrupt line acts a a gate for the memory output. The bank can
output when the interrupt line is asserted, and will stop when the interrupt
line is de- asserted.
When you have set the polarity and mode, enable the interrupt using the
SOURce:DIGital:INTerrupt:ENABle command.
Memory Input Operations
For memory input operations, the interrupt line is an output and is set on a
pattern match or when the memory has been filled. You can set the interrupt
line to be driven or open collector using the
SENSe:DIGital:HANDshake:DRIVe command.
When set to ACTive the interrupt line will be driven by the instrument. The
high output voltage is set for both the handshaking and interrupt line on a
bank with the
SOURce:DIGital:HANDshake:LEVel command.
When set to
OCOLlector the interrupt line will be driven low, but will go to
high impedance mode when in the ‘High’ state. The open collector mode
requires external pull- ups.
The
SENSe:DIGital:INTerrupt:MODE command sets the condition that will
cause the interrupt to be asserted. When set to MFULl the interrupt is given
when the memory is full. When set to COMPare the interrupt is asserted when
the pattern is detected (see page page 215). When either condition is
removed, the interrupt is de- asserted.
The interrupt line is enabled by the
SENSe:DIGital:INTerrupt:ENABle
command and the status can be checked using the SCPI Status System (refer to
the Programmer's Reference Help file on the L4400 Product Reference
CD- ROM).
Byte Ordering
When using buffered memory operations, the width of the data sets how the
memory data is interpreted. Changing the width of the first channel in a bank
invalidates any traces stored or captured.
Output Operations For output operations (see page 210), traces are put
into memory using the TRACe:DATA:DIGital command.
NOTE
The settings for drive mode, output drive level, and input threshold also
apply to the bank’s handshake lines.