Sudden Hang of SLC 5/03 AB PLC

We've AtlasCopco Compressor which is control by SLC 5/03 plc. Now very frequent plant trip showing erorr 250/956 etc at different time and it goes to hang situation.....

Can any one suggest what we can do now...

Explain exactly what you mean by "showing erorr 250/956".

Are those error codes indicated in RSLogix 500 software, or on some kind of operator interface ? I have no idea what constitutes a "plant trip" for you.

Thanks Ken.

The interface showed PLC fault and at RSlogix 500 software we found this kind of error code.

At inter face showing PLC fault it trips the Compressor which ultimately trpis the plant.