User`s manual

Understanding the Agilent E1330B Digital I/O Module 45
Chapter 4
Handshake Modes The operation of each handshake mode for input or output operations is
described in the following subsections. In these discussions, only the FLG,
CTL, and DATA lines are included. Other port control lines, controlled only
through register access, are described in Appendix B of this manual.
LEADing Edge The LEADing Edge handshake makes use of both the CTL and FLG lines.
The input and output operations are described below.
INPUT OUTPUT
1 The Digital I/O module senses the
FLG line and waits for READY.
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 HIGH.
2 The Digital I/O module sets the
I/O line LOW.
3 The Digital I/O module sets CTL
TRUE.
3 The Digital I/O module places the
data on the data lines.
4 The peripheral senses the CTL
line and places 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 sets the FLG line
to BUSY indicating data is valid.
5 The peripheral senses the CTL
line and sets the FLG line to
BUSY while it latches the data.
6 The Digital I/O module senses the
FLG line and 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 The Digital I/O module returns
CTL to FALSE.
7 When the peripheral returns the
FLG line to READY (indicating it
has latched the data) the next
handshake can begin.
8 The peripheral senses the CTL
line and returns the FLG line to
READY.