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210 L4400 User’s Guide
8 L4450A 64-Bit Digital I/O with Memory and Counter
Buffered I/O Operations
Each of the two banks on the L4450A has its own memory that can be used to
store patterns to output (traces) or to store input patterns. The width of the
first channel in each bank controls the width of the memory operations.
Memory may be used as:
• 64K x 8 bits
• 64K x 16 bits
• 32K x 32 bits
Buffered (Memory) Output
Each bank on the L4450A has its own memory for use in buffered transfers.
Changing a bank from an input to an output will clear all memory for that
bank. For buffered outputs, you download “traces” of digital data to the
memory. Multiple traces (up to 32) can be downloaded into each bank. A
specified trace is then output using the handshaking parameters set.
The general steps to output from memory are:
1 Set the channel width and direction.
2 Set the handshake mode.
3 Set the trigger source.
4 Set the number of times to output the trace.
5 Load the trace(s) into memory.
6 Set which trace to use.
7 Enable the memory.
8 Trigger the output.
Set the channel width and direction. Use the SOURce:DIGital:DATA command
to set the channel width and set the channel as an output. Additionally, the
data specified in the command will be the initial state of the data lines before
the memory operation begins.
Set the handshake mode. You must use synchronous handshaking mode.
You can use either an internal or external strobe (clock) to pace the outputs.
Handshaking is described in more detail on page 203.
Set the trigger source. By default, the trigger source is set to use a software
trigger. You can also use one of the interrupt lines (see page page 213) as
a trigger source.