fault light on ML1400

[leonlai]

It was running for months, oneday fault light on, check and see:
Data File S2 - Errors Tab:

Fault Override At Powerup S:1/8 = 1
(the rest is 0)

Major Error S:6 = 34 h (A negative value for a timer accumulator...)

I did set Overflow Trap S:5/0 (U).

what was wrong ??

Thanks

 

[bernie_carlton]

That error is not an 'overflow'. You must take active measures to prevent a negative value being applied to a timer Preset.

 

[leonlai]

Thank for your reply,

what do you mean take active measures ??

All of Timer Preset are input by user throu PLC.
Does it mean by mistake user put negative preset timer so it cause the Error ??

 

[bernie_carlton]

Does it mean by mistake user put negative preset timer so it cause the Error ??

Yes, either the user entry must be limited to prevent this or have the entry write to a standard integer then test it before moving it into the timer preset.

 

[robo77]

He is right on again!! Yes check the input in the plc first before moving value. or if direct change the hmi to not accept "bad" values lol just reread you response, now I sound like a parrot...lol

 

[olsq]

I apologize in advance for resurrecting the past.
This thread was the only result a quick forum search yielded.
I got called out to a simple machine and found the ML1000 faulted with major error 34.
Small program with only 13 timers.
The data table showed all acc values at 0. I went through and ck'd all the preset values at each timer instance.
all are set to positive values.
all the timer presets are static values and not stored in integer files. There is no hmi and the program doesn't do any math.
I was able to clear the fault and reset the machine. it has been operating for about 30 mins now.
I am just curious if the wealth of experience here on the forum would have any idea as to how this fault came about.
Thanks