Bradley Smoker PLC-5 user manual Setting an Alarm, Clearing a Major Fault, Alarm output

Preparing Fault Routines 15-7

Setting an Alarm

If you need an alarm to signal the occurrence of a major fault, put this rung first in your fault routine program:

alarm output

and combine it with a counter. You can also set an alarm in your fault routine to signal when the fault routine clears a major fault.

Clearing a Major Fault

You can clear a major fault with one of these methods:

•Turn the keyswitch on the PLC-5 controller from REM to PROG to RUN.

•Use the programming software to clear the major fault (if recoverable).

ATTENTION	Clearing a major fault does not correct the cause of the
	fault. Be sure to examine the fault bit and correct the
	cause of the fault before clearing it.

For example, if a major fault is encountered causing bit S:11/2 to be set, indicating a programming error, do not use a fault routine to clear the fault until you correct your program.

If you decide to clear the fault in the fault routine, follow these steps:

1.Place the ladder logic for clearing the fault at the beginning of the fault routine.

2.Identify the possible major faults.

3.Select only those your application will let you safely clear. These are your reference fault codes.

4.From the fault routine, examine the major fault code that the controller stores in S:12.

5.Use an FSC instruction to compare the fault code to the reference file that contains “acceptable” fault codes (word-to-file comparison).

Publication 1785-UM012D-EN-P - July 2005