Rockwell Automation 2705 REDIPANEL KEYPAD MODULE USER MANUAL - Manual (Page 67)

Chapter 7
Programming
7–29
With the handshake feature enabled and the handshake rung in the user’s
program, the RediPANEL module holds all function key input signals high
for a minimum of one complete PLC program scan. It keeps the signal(s)
high for one complete cycle of the handshake input bit. The handshake input
and output signals will continuously toggle independent of any function key
closures. This ensures that the handshake function is operational even if no
function keys have been pressed. The timing diagrams (Figure 7.12) further
explain how this is accomplished.
IMPORTANT: The following diagrams are used for illustrative purposes
only and are not intended to be precise timing diagrams. Exact timing
diagrams vary from application to application and are dependent upon the
number of remote I/O nodes, program scan time, etc.
Figure 7.12
Handshake Timing Diagrams
Handshake Input Bit 17
Handshake Output Bit 17
Read Inputs
Write to Outputs
Program Scan
Function Key Contact
Function Key Input
Handshake holds the function key input high even if the function
key contact signal goes low.
PLC Scan Cycle