11 TROUBLESHOOTING

MELSEC-Q

Example 5

Example 6

Input Circuit Problems and Corrective Actions (Continued)

Condition

 

 

 

Cause

 

Corrective Action

 

• Sneak path due to the use of two power

• Use only one power supply.

 

supplies.

 

 

 

 

 

 

 

• Connect a sneak path prevention diode.

Input signal

 

 

 

 

 

 

 

 

(Figure below)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

does not

1

 

2

 

 

 

 

Input module

 

 

 

 

 

 

 

 

turn OFF.

E

E1

E

 

 

 

 

 

E1 E2

 

 

 

 

 

 

Input module

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

>E2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Change response time setting.

 

 

 

 

 

 

 

 

 

Example : 1ms

 

5ms

 

 

 

 

 

 

 

 

 

(Setting of a shorter response time may produce

False input

 

 

 

 

 

 

 

 

a higher effect on periodic excessive noise.)If no

Depending on response time setting, noise is

effects are produced by the above, take basic

due to

imported as input.

 

 

 

 

 

actions to prevent excessive noise form

noise

 

 

 

 

 

 

 

 

 

 

 

 

 

entering, e.g. avoid bundling the power and I/O

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

cables, and suppress noise by adding surge

 

 

 

 

 

 

 

 

 

absorbers to such noise sources as relays and

 

 

 

 

 

 

 

 

 

conductors used with the same power supply.)

11 - 39

11 - 39