User`s manual

Troubleshooting I/O circuit troubleshooting
11 – 98
5 Input signal is not
turned off.
Sneak path due to the use of two
power supplies.
Use only one power supply.
Connect a sneak path prevention diode.
6 Input signal is not
turned on (AC input
module)
Stepwise distortion as shown below
appears to the zero cross voltage of
input signal (AC).
Improve input signal waveform by using
the online system etc.
7 False input due to
noise
Depending on response time setting,
noise is imported as input.
Change the response time setting.
Example: 1 ms to 5 ms
Exam-
ple
Condition Cause Corrective action
Tab. 11-1: Input circuit troubleshooting
Input
module
U2U1
U1 > U2
U1
Input
module
U2
Zero cross
voltage