When you run this program you will see that it causes the temperature to return to 25°C (point 6 in the diagram) at 3 minutes after the start of the cycle,not at 1minute 40 seconds as listed. This is because the looping interferes with Format 550's timekeeping.
Due to the disruption of the internal timekeeping, the listing of events that succeed loops is no longer derived directly from the start of the cycle. A simple calculation is required to determine when to program the statement for each succeeding event
CALCULATION FOR SUCCEEDING EVENTS
Call the target time for the succeeding event, the "event statement time". Call the time when the event is required the "event actual time". (Both times are from the start of the cycle.)
event statement time = event actual time - total looping time
The "total looping time" is the time to execute the loops as defined by LS & Rep.
If in the above example it is required to end the cycle at 3:40:
event statement time = 3:40
EXAMPLE 2
in the following example the temperature is required to reach 95°C at 4 minutes 55 seconds into the
event statement time = 4:55
4:55 event actual time (when you want it to occur)
1:45 total looping time (Rep multiplied by the time from the start of the loop to its end)
To do this you would program:
Seg | Time | T e m p H u m | |
| dd:hh:mm:ss | °C |
|
000 | 00:00:00:00 |
|
|
001 | 00:00:00:01 | 25.0 | 65 |
002 | 00:00:00:20 | 85.0 |
|
003 | 00:00:00:40 | 35.0 |
|
004 | 00:00:01:00 | 65.0 |
|
005 | 00:00:01:20 | 15.0 |
|
006 | 00:00:01:40 | 25.0 |
|
007 | 00:00:02:40 | 10.0 |
|
008 | 00:00:02:20 | 25.0 |
|
009 | 00:00:02:10 | 95.0 |
|
010 | 00:00:04:00 | 25.0 |
|
LS Rep Digital Channels
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