Rockwell Automation 2705 RediPanel Push Button Module - Manual (Page 59)

Chapter 4
Programming the RediPANEL Modules
4–20
Response time is the amount of time it takes the RediPANEL Module to
respond to a depression of a button.
The RediPANEL Module uses the Scanner Module to tell the PLC when a
button is pressed. The Scanner Module takes a maximum of 7.0 milliseconds
to scan a device, unless there is electrical noise. A maximum of 16 physical
devices may be connected to any single Scanner Module channel. The
maximum time between reading button depressions is:
7.0 milliseconds/device
×
16 devices = 112 milliseconds
The worst case occurs when a second button is pressed while a 64 word
block transfer is pending. A calculation for this condition is:
0.5 milliseconds/word
×
64 words = 32 milliseconds
When you add these two figures together, you get:
112 milliseconds + 32 milliseconds = 144 milliseconds
Therefore, if a button is pressed, released and pressed again within 144
milliseconds, the second press is missed by the Scanner Module. To deal
with the response time factor:
1. The RediPANEL Module maintains each press of a push button in
the ON state for a minimum of 100 milliseconds (in the Timed Mode) or
until it is recognized by the PLC (in the Handshake Mode).
2. The push button must be released for 50 milliseconds between
presses or the second press is ignored.
Response Time