Agilent Technologies manual L4400 User’s Guide 207

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

Synchronous Buffered Inputs You can use synchronous mode handshake with buffered (memory) input operations. (Buffered operations are described in more detail beginning on page 210.) For buffered input operations, the H0 line acts as a start/stop line. This line will be set high when the memory input command is executed and will return low when the memory input operation has completed. The H1 line is not used and is set to high impedance.

An external strobe input on the H2 line controls the pace of memory transfers.

The sending device must ensure the data is valid before the TSETUP and stays valid until after THOLD. TSETUP is 30 ns and THOLD is

55 ns.

A synchronous buffered input using an external clock is shown in the diagram below (default handshake line polarity).

H0 (Start/
Stop)
		> 50 ns		TCYCLE > 100 ns
								(Last Cycle)
H2 (Strobe In)
		TSETUP	THOLD		TSETUP	THOLD
Data In	Don't-Care	Valid		Don't-Care	Valid		Don't-Care	Valid	Don't-Care

For example, the following SCPI commands set the L4450A to have an 8- bit input using synchronous handshake with an external strobe input. The number of bytes to read into memory is set to infinite (continuous reading into memory until the memory is stopped). The memory is enabled and then triggered. The start/stop line is set high following the first byte handshake and remains high until the last byte is captured.

CONF:DIG:WIDT BYTE, (@1101)

CONF:DIG:DIR INP, (@1101)

CONF:DIG:HAND SYNC, (@1101)

SENS:DIG:MEM:SAMP:COUN 0, (@1101)

SENS:DIG:MEM:ENAB ON, (@1101)

SENS:DIG:MEM:STAR (@1101)

L4400 User’s Guide 207