Handshaking – Agilent Technologies L4400 User Manual
Page 215
L4450A 64-Bit Digital I/O with Memory and Counter
8
L4400 User’s Guide
203
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
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
) 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
Input
I/O Direction
(output)
Strobe
(output)
Not Used (Hi-Z)
Unbuffered Synchronous
Output
I/O Direction
(output)
Strobe
(output)
Not Used (Hi-Z)
Buffered Synchronous
Input
Start/Stop (output)
Not Used
(Hi-Z)
Input Strobe
(input)
Buffered Synchronous
Output (internal clock)
Start/Stop (output)
Strobe
(output)
Not Used (Hi-Z)
Buffered Synchronous
Output (external clock)
Start/Stop (output)
Not Used
(Hi-Z)
Output Strobe
(input)