Agilent Technologies L4400 manual Handshaking, Output

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

This command sequence sets the first 8 bits (channel 101) to normal polarity for input and output operations, set the next 8 bits (channel 102) to inverted polarity, and then combines the bits into a 16- bit channel. When this WORD channel is used, the first eight bits will input or output using normal polarity but the next 8 bits will read or written using inverted polarity.

Threshold, level, and drive settings all behave in the same manner as the polarity setting described above.

Handshaking

Handshaking provides a means to synchronize the input or output of digital data. By default, no handshaking is used and data is input or output as the command is executed. The handshake is configured per bank.

The L4450A provides a synchronous strobed handshake mode. You can use this mode with basic input and output operations. You must use this handshake mode to use buffered I/O (see “Buffered I/O Operations” on page 210).

The handshake is performed using three lines on each bank. The lines are labeled H0, H1, and H2. The function of each line is set by the input or output mode in use. Since there are only three handshake lines per bank, the SCPI handshake commands are only valid for the first channel in a bank. Once handshaking is enabled, it applies to the width of the first channel in the bank.

The three handshaking lines on each bank also differ slightly if you are using buffered (see page 210) or unbuffered I/O operations. You can also perform unbuffered operations without any handshake. The function of each line for each mode of operation is defined in the table below.

	H0	H1	H2
Unbuffered Synchronous	I/O Direction (output)	Strobe (output)	Not Used (Hi-Z)
Input
Unbuffered Synchronous	I/O Direction (output)	Strobe (output)	Not Used (Hi-Z)
Output
Buffered Synchronous Input	Start/Stop (output)	Not Used (Hi-Z)	Input Strobe (input)
Buffered Synchronous Output	Start/Stop (output)	Strobe (output)	Not Used (Hi-Z)
(internal clock)
Buffered Synchronous Output	Start/Stop (output)	Not Used (Hi-Z)	Output Strobe
(external clock)			(input)

L4400 User’s Guide 203