Handshaking
Agilent 34950A 64-Bit Digital I/O and Counter Module User’s Guide
7
Handshaking
Handshaking provides a means to synchronize the input or output of
digital data. By default, no handshaking is used; data is input or output as
the command is executed. The handshake is configured per bank.
The 34950A provides a synchronous handshake mode (strobe handshake).
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 14).
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 (memory) I/O (see
page 14
) 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.
The following handshake command sets the synchronous handshaking
mode for the channels in bank 1.
CONF:DIG:HAND SYNC, (@1101)
This form of the handshaking command also allows you to optionally set
the input threshold, output drive level, and polarity of all the handshake
lines. For example, the following command sets bank 2 to use synchronous
handshaking, with an input threshold of 2.5 V, an output drive level of
2.5 V, and normal polarity. Other parameters such as the handshake
timing are set to default values (refer to the
Programmer’s Reference
Help file
for details
)
.
CONF:DIG:HAND SYNC, 2.5, 2.5, NORM, (@1201)
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)
