Chapter 6 CPU Functions
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6.5.2 Processing time and processing method of Force Input/Output On and Off
(1) Forced Input
Regarding input, at the time of input refresh it replaces the data of contact set as Force On/Off among
data read from input module with the data as Force and updates input image area. Therefore, user
program executes operations with actual input data while Force input area is operated with data set as
Force.
(2) Forced Output
Regarding output, at the time of output refresh upon the execution user program operation, it replaces
the data of contact set as Force On/Off among data of output image area containing operation results
with data set as Force and outputs the data in output module. Unlike (Force) input, the output image
area is not changed by Force On/Off setting.
(3) Cautions when using Force I/O function
(a) It operates from the time when I/O is individually set as „Allow‟ after setting Force data.
(b) It is possible to set Force input although I/O module is not actually mounted.
(c) Despite of the power changed Off -> On, operation mode changes or any operation by pressing reset
key, the data of which On/Off is set before is kept in CPU module.
(d) Even in STOP mode, Force I/O data is not removed.
(e) To set new data from the beginning, it is necessary to deselect all settings of I/O by using „Delete All‟
option.
(4) Operation in case of error
(a) If error occurs after setting forced output, PLC operates based on “Keep output when an error occurs”
in Basic parameter and “Emergency output” in I/O parameter.
If you set “Emergency output” as “Clear” after setting “Keep output when an error occurs”, output is
cleared when an error occurs. If you set “Emergency output” as “Hold” after setting “Keep output when
an error occurs”, output is held when an error occurs.
(b) If you don‟t set “Keep output when an error occurs”, output is off when an error occurs.
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