Timebomb

[can]

Hi. Does anybody know of any way to time bomb the program in FMD88?

[support]

Do you want to partially disable your program or you want to entirely shut it down? The best way to time bomb the program is to define a counter/timer to specify the limitations on your application and when that value is reached, the entire program or partially will shut down. For instance in preventive maintenances, programmer decides to stop the system working but should keep the life safety related sections of the program fully functional.

[can]

Hi. I'm thinking of deleting the entire program in PLC permanently when a counter is up. Is there any key words that can enable me to do it using Tbasic? Thank you.

[garysdickinson]

I have found no TBASIC keywords that can directly alter the stored program.  You can alter SV of TIMERs and COUNTERs.  

If your PLC has non-volatile EEP storage you can wipe this out.  I use EEP to store all sorts of configuration data so that my customer can run the same PL6/7 program on several systems.  Only the EEP image changes between systems.

Why do I mention this?  I look for a unique signature in EEP to determine if the EEP based configuration data is valid. If valid, the code runs.  If not valid the code builds a generic configuration data set in EEP.

For your usages, when the usage counter expires,  zero out the EEPROM and reset the PLC.  The CF that is called on the first scan can simply put the PLC in an endless loop if the EEP has been cleared. This will brick the PLC for 99.9% of your customers.



Best regards,

Gary D*ickinson