Chapter 13 Troubleshooting

The CPU operates, but output signals are not detected.

Is the LED lit?

NO

 

YES

Check the program

Is there a wiring error,

YES

disconnection or loose

 

 

 

 

 

 

screw on the terminal

 

 

 

 

 

 

block?

 

Perform rewiring

NO

 

 

 

NO

Is the relay drive power

supply connected?

 

 

 

YES

Is the voltage satisfying

NO

the specification in the

 

terminal block? Is the

 

polarity correct?

 

YES

 

Are there any problem in

YES

internal contactors of the

 

terminal block?

 

NO

Contact our service department

Supply 24 VDC power

Change the voltage and polarity to satisfy the specifications

Replace the terminal block

I/O assignment error occurred, but output is normal.

Are the program and

NO

I/O assignment

 

 

 

 

 

 

correct?

 

 

 

 

Correct the error

 

 

 

 

YES

 

 

 

 

YES

 

 

 

Is the expansion unit

 

cable damaged?

 

 

 

 

 

 

 

 

 

Replace the expansion unit

 

NO

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Replace the expansion cable

 

 

 

 

 

 

 

 

13-14

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Hitachi NJI-350B CPU operates, but output signals are not detected, Assignment error occurred, but output is normal, 13-14