PLC Program Checksum Failure

[BC SYSTEMS]

Hi,

We had a failure on a site that has 10+ of your TMD PLC's.  The red pause LED was lit and dispite cycling the power, the PLC the problem remained.

I used the online monitoring function and noticed the following message from the PLC  was "PLC program checksum failure, please reload program"

The program has been running for 18 months without a glitch.  I reloaded the program and the syatem was back online.  

What do you think would cause this error as we have not had this message before?

Cheers

[support]

It appears the PLC's EEPROM program was corrupted. This is usually caused by high energy voltage spike coming in through the power supply terminal. Was there a recent power failure or lightning strike to the facility? Was the facility using some kind of battery backup system during power failure. Some load-dump effect from power backup could also corrupt or even damage the EEPROM. After you have transferred the program to the PLC you should power cycle the PLC to ensure that the EEPROM will boot up properly, otherwise the T100MD+ PLC may actually run OK using the program transferred to its RAM but may fail when it next boot up.

If this is becoming a more than once in a blue moon occurence, you should consider adding power surge protection circuit to AC input into the DC power supply to filter out high energy voltage spike.

[BC SYSTEMS]

Hi,

The PLC is connected to a regulated power supply. We dont use any batteries in the panel as the system controls some ac pumps - no ac no running.

When the system looses power I guess there will be some spikes from relays coils collapsing etc.

Can you recommend a suitable surge protection device?

Cheers.  

[support]

It is best to consult a local electrical supplier for a AC surge suppressor/lightning protector module to be attached between the AC power and the AC terminal of your regulated power supply.