Keysight VXI Bus 75000 C Series User And Programming Manual page 46

Using the Keysight E1458A Digital I/O Module
LEADing Edge
The LEADing Edge handshake makes use of both the CTL and FLG lines. The
input and output operations are described below.
INPUT
1. The digital I/O module senses the
FLG line and waits for READY.
2. The digital I/O module sets the I/O
line HIGH.
3. The digital I/O module sets CTL
TRUE.
4. The peripheral senses the CTL line
and places data on the data lines.
5. The peripheral sets the FLG line to
BUSY indicating data is valid.
6. The digital I/O module senses the
FLG line and latches the data.
7. The digital I/O module returns CTL
to FALSE.
8. The peripheral senses the CTL line
and returns the FLG line to READY.
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OUTPUT
1. The digital I/O module checks the
state of the FLG line (must be
READY).
2. The digital I/O module sets the I/O
line LOW.
3. The digital I/O module places the
data on the data lines.
4. After waiting the programmed
delay time, Td, the digital I/O module
sets CTL to TRUE.
5. The peripheral senses the CTL line
and sets the FLG line to BUSY while
it latches the data.
6. When the digital I/O module
senses the FLG line in the BUSY
state, it sets the CTL line to FALSE
and monitors the FLG line.
7. When the peripheral returns the
FLG line to READY (indicating it has
latched the data), the next
handshake can begin.
Keysight E1458A 96-Channel Digital I/O Module User Guide
Using the Handshake Modes