Agilent Technologies L4400 manual Data line polarity

L4450A 64-Bit Digital I/O with Memory and Counter 8

Set the number of times to output the trace. Each trace can be output once, multiple times, or infinitely. The SOURce:DIGital:MEMory:NCYCles command sets the number of times to output the trace. If not set to infinite, you can output the trace from 1 to 255 times (the output is controlled by the handshake).

Load the trace(s) into memory. Named traces are downloaded using the TRACe:DATA:DIGital command. The channel width used should match the width of the channel set in step 1. If you change the width of a bank, all traces in memory are cleared. The trace names must start with a character and may be up to 12 characters in length. The trace name used must be unique to the bank. Up to 32 traces may be downloaded.

Traces can be added or deleted only when memory is disabled. Memory output cannot be enabled unless the bank has a trace assigned to it.

For example, the following commands load two traces into memory for bank 1. In this example, each byte of the LWORd to output is sent as a separate byte.

TRAC:DATA:DIG:LWOR (@1101), MyTrace1, 255, 200, 128, 0 TRAC:DATA:DIG:LWOR (@1101), MyTrace2, 254, 192, 64, 32

You can also send trace data in IEEE- 488 block format using this command.

The L4450A also has two special built- in traces for your use. You can generate and download a count- up trace and a walking 1’s pattern using the TRACe:DATA:DIGital:FUNCtion command. See the Programmer's Reference Help file on the L4400 Product Reference CD- ROM for more details.

N O TE	You can generate a count-down or walking zero pattern by inverting the
	data line polarity.

Set which trace to use. The SOURce:DIGital:MEMory:TRACe command assigns the desired trace to the bank. This command allows you to switch between the traces pre- loaded into the bank’s memory.

Enable the memory. Enable the memory on the bank using the SOURce:DIGital:MEMory:ENABle command. This command sets the selected trace to be the output and puts the bank in the wait- for- trigger state.

Trigger the output. When the default trigger source is used, the SOURce:DIGital:MEMory:STARt command triggers the output. The selected trace will be output when the handshake occurs.

If the trigger source has been set to one of the interrupt lines (see page page 213), the output will wait for the interrupt to occur and then the handshake to occur before the trace is output.

L4400 User’s Guide 211