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[Design Precautions]
Precautions for using digital-analog converter modules
and analog input/output modules
● When a module is faulty, analog outputs may remain on. Configure an
external circuit for monitoring output signals that could cause a serious
accident.
Precautions for using high-speed counter modules and
flexible high-speed I/O control modules
● Outputs may remain on or off due to a failure of a transistor for external
output. Configure an external circuit for monitoring output signals that could
cause a serious accident.
Precautions for using positioning modules
● Configure safety circuits external to the programmable controller to ensure
that the entire system operates safely even when a fault occurs in the external
power supply or the programmable controller. Incorrect output or malfunction
due to a communication failure may result in an accident.
(1) Machine OPR (Original Point Return) of the positioning module is
controlled by two kinds of data: an OPR direction and an OPR speed.
Deceleration starts when the near-point watchdog signal turns on. If an
incorrect OPR direction is set, motion control may continue without
deceleration. To prevent machine damage caused by this, configure an
interlock circuit external to the programmable controller.
(2) When the head module detects an error, the motion slows down to stop or
suddenly stops, depending on the stop group parameter setting. Set
parameters according to the positioning system specifications. Also, set
the OPR parameters and positioning data within the parameter setting
range.
(3) Outputs may remain on or off, or be undefined due to a failure of a
component such as an insulated element or a transistor in an output
circuit, where the head module cannot detect any error. Configure an
external circuit for monitoring output signals in a system where an
incorrect output could cause a serious accident.
● An absolute position restoration by the positioning module may turn off the
servo-on signal (servo off) for approximately 60ms, and the motor may run
unexpectedly. If this causes a problem, provide an electromagnetic brake to
lock the motor during absolute position restoration.
WARNING
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