11 TROUBLESHOOTING
11.5 Examples of Troubles with the I/O Module
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When output is turned on, load connected to other outputs is turned on simultaneously
■Cause
When a non-wiring state occurs due to, for example, a shutoff or disconnection between 0V of the external power supply and
the common of a load, a current flows across the load that is off through an unexpected circuit of the output element that is off.
■Action
Connect external power supply and the load correctly.
To prevent the state described above, install diodes in each output terminal as shown below.
ON
OFF
Y0
Y1
COM+
CTL-
Load
Load
24VDC
Shutoff or disconnection
Source output
Output control
circuit
Output control
circuit
Output module
Y0
Y1
COM+
CTL-
Load
Load
24VDC
Source output