Relays, Memory Areas and Constants
1-24
1.2 Explanation of Relays
1.2.1 External Input Relays (X)
Function of external input relays (X)
This relay feeds signals to the programmable controller from an external device such
as a limit switch or a photoelectric sensor.
Input: on
Input
unit
XY
Input
X contact: on
Program
CPU
Usage restrictions
The addresses for inputs which do not actually exist cannot be used.
The on or off status of the external input relays cannot be changed by the program in
the programmable controller.
There are no restrictions on the number of times one external input relay is
programmed.
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