Mitsubishi Electric MELSEC iQ-R Series Configuration Manual page 6

[Design Precautions]
WARNING
[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 flexible high-speed I/O control modules]
● When changing data and operating status of the running module from an external device such as a
personal computer connected, configure an interlock circuit external to the programmable controller to
ensure that the entire system always operates safely. In addition, before performing online operations,
determine corrective actions to be taken between the external device and the module in case of a
communication failure due to poor contact of cables.
[Precautions for using positioning modules and Simple Motion 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.
Failure to do so may result in an accident due to an incorrect output or malfunction.
(1) Machine OPR (Original Point Return) is controlled by two kinds of data: an OPR direction and an
OPR speed. Deceleration starts when the near-point dog 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 positioning module detects an error, the motion slows down and stops or the motion
suddenly stops, depending on the stop group setting in parameter. Set the parameters to meet the
specifications of the positioning control system used. In addition, set the OPR parameters and
positioning data within the specified setting range.
(3) Outputs may remain on or off, or become undefined due to a failure of a component such as an
insulation element and transistor in an output circuit, where the positioning module cannot detect
any error. In a system where the incorrect outputs could cause a serious accident, configure an
external circuit for monitoring output signals.
● An absolute position restoration by the positioning module may turn off the servo-on signal (servo off)
for approximately 60ms + scan time, and the motor may run unexpectedly. If this causes a problem,
provide an electromagnetic brake to lock the motor during absolute position restoration.
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