IDEC High Performance Series - Manual (Page 1238)

2 Digital I/O Units
29-4 WindO/I-NV2 User’s Manual
●
Operation with priority on display processing
When an external input occurs
■ Display processing
Parts placed on the screen are processed in order from the top down. This process constitutes a single scan.
When processing reaches the end, it returns to the beginning and starts the next scan.
The time for one scan depends on the number and type of parts used, as well as how they are configured.
■ Input refresh
Inputs are refreshed every 10 ms independent of the screen scan.
However, inputs at the digital I/O unit are not reflected in the HG Digital Input (LEX) until the screens scan ends.
■ Input delay
When an external input occurs on the digital I/O unit, the delay time until the input is reflected in the HG Digital Input
(LEX) will be at least 5 ms or a maximum of 15 ms + the scan time (HG special registers LSD 4).
The longer display processing takes, the longer the delay.
Control processing
Digital I/O unit input
Input
refresh
LEX
X
10 ms
Input
refresh
10 ms
Input
refresh
10 ms
Scan time
Input delay
Input
delay
Start of scan
Display
processing
1 scan
External input
X
External input
HG Digital Input
End of scan
Input delay is longest when an input occurs on the digital I/O unit
immediately after the scan begins because it does not get reflected
in the HG Digital Input (LEX) until the beginning of the next scan.
LEX
X
Input
refresh
Display
processing
1 scan
HG Digital Input
External input
Input delay
(maximum)