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2. DESIGN
2
−
15
(4) Failsafe measures for Motion controller failure
Failure of the CPU module or memory is detected by the self-diagnosis
function, but some abnormalities in the I/O control components cannot be
detected by the CPU.
Some failures can result in situations such as all points turning on or off, where
normal operation and safety of the controlled object cannot be assured.
The manufacturer makes every effort to ensure perfect quality control.
However, external failsafe circuits should be provided to prevent accidents or
damage to machines in the event that a failure does occur in the CPU module.
An example of a failsafe circuit is shown in the diagram below.
Internal program
M9032
Y00
Y00
0.5s 0.5s
Y00
Y01
Y0F
24V
0V
CPU module Output
module
*1
24VDC
T1
T2
MC
L
L
MC
1s
1s
T2
T1
External load
Off-delay timer
On-delay timer
CAUTION
*1 : Use a non-contact output module for Y00, as it turns ON/OFF at 0.5 s intervals. A transistor
is shown in the example above. Using a contact module for Y00 can cause failures.