S7 300 recording variables

Hi, I have a machine that drops it's control voltage at random occasions. I am currently monitoring all the bits that could cause this problem, but I am having to sit here and watch them in a variable table.

Is there any way that I could record the events of the bit changes and when the control is lost I could just look at the log and see which bit caused the fault?

Thanks in advance for any and all help.

BTW, I am using S7 V5.4

Thanks

Here's a sample program that writes user events into the diagnostic buffer. The diagnostic buffer gives the time/date of the event and you can store additional info in the entry to show which event ocurred.

Here's the diagnostic buffer entries for the simulated events: