GEM80-400 2. Controller Architecture and Program Operation
Issue 3 04/99 ALSPA GEM80-400 SERIES CONTROLLERS TECHNICAL MANUAL Page 2-3
repetition interval has been preset, a waiting period is inserted after the program
execution at the end of the cycle. The program execution time itself varies due
to blocks within the user program, and so the waiting period also varies in order to
make the cycle time up to the preset interval. The timing of the output scan is
therefore held to a regular interval, varying very little, which is an advantage for
continuous analogue control applications. Data written by the user into the P-
table determines whether the controller is free-running or preset. See the 'P-Data
Table' section, later in this chapter, for details. Cycle time calculation and
measurement is discussed in the 'Calculating and Program Scanning Interval'
section of this chapter.
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