Input Circuit Troubles And Corrective Actions - Mitsubishi Electric MELSEC iQ-R Series User Manual

9.2

Input Circuit Troubles and Corrective Actions

An input signal does not turn off.
■Case 1
Cause There is a leakage current from the input switch (driven by a contactless switch and others).
Action Connect an appropriate resistor so that the voltage between terminals of the input module would fall below the OFF voltage.
The recommended CR constant is as follows: 0.1 to 0.47F + 47 to 120 (1/2W).
■Case 2
Cause There is a leakage current from the input switch (driven by a limit switch with neon lamp).
Action Take any of the following actions:
• Connect an appropriate resistor so that the voltage between terminals of the input module would fall below the OFF voltage. (same
action as the case 1).
• Make the circuit independent and provide another display circuit.
■Case 3
Cause There is a leakage current due to the line capacity of the wiring cables. (The line capacity, C, of a twisted pair cable is as follows: C =
approx. 100pF/m.)
Action Connect an appropriate resistor so that the voltage between terminals of the input module would fall below the OFF voltage. (same action
as the case 1).
A leakage current is not generated, however, where the power supply lies in the input device side like the figure below:
9 TROUBLESHOOTING
120
9.2 Input Circuit Troubles and Corrective Actions
AC input
C
Leakage
Input module
current
Power supply
AC input
C
Input module
R
Power supply
AC input
Leakage
Input module
current
Power supply
AC input
Leakage
Input module
current
Power supply
AC input
Input module
Power supply