Tamper Resistant Hour Meter Logix5000

DamianInRochester

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Are there any ideas on how to make a "reasonably" tamper proof running hour meter for a compact logix?

My OEM customer wants to base their machine warranty on "run" hours and not necessarily "power on" hours.

Maybe a simpler way to look at the problem is if it is possible to in some fashion make a tag value password protected such that I can write it inside say a locked AOI but noone outside can write to it?

Obviously there are other ways to get around it (replace the CPU, modify the program, etc.), but those at least require more effort than simply resetting a number. The more difficult it is the less apt they are to futz with it.
 
QUOTE]My OEM customer wants to base their machine warranty on "run" hours and not necessarily "power on" hours.[/QUOTE]
very nice of them most my vendors base their warranty on date sold + 1year(or what ever) do they expect you to warranty your work and material on this time base too.
If so be carefull! you could provide parts or labor on somthing sold today and still under warranty long after you rember what a compact logix is.o_O
 
You can configure the TOT instruction to totalize time. See http://www.plctalk.net/qanda/showpost.php?p=347436&postcount=6.

If you don't use the TOT instruction and use regular timers then be aware that unless you are careful you can introduce significant timing errors over a period of time just due to to scan time timing errors. The timing errors could have significant legal implications if you are using the timer for warranty issues. If you don't have the language extensions and have to use RTO/TON then we can discuss how to overcome these problems (Its been covered in other threads).

I don't know of a foolproof way to track running hours inside the CLX. You can imbed internal tags in an AOI and track it there but it doesn't prevent it from being changed if a download occurs.

You can purchase external non-resettable run hour timers.

You could also store the value in memory of an external HMI unit. If there is ever a discrepancy then a subroutine (maybe the locked AOI) could decide which one to use and reset to that value.
 
Last edited:
QUOTE]My OEM customer wants to base their machine warranty on "run" hours and not necessarily "power on" hours.
very nice of them most my vendors base their warranty on date sold + 1year(or what ever) do they expect you to warranty your work and material on this time base too.
If so be carefull! you could provide parts or labor on somthing sold today and still under warranty long after you rember what a compact logix is.o_O[/quote]

It will be based on a Date and Runtime.

I generally warranty anything purely engineering indefinitely. If I screw it up I expect to have to fix it.

If it is a build, the parts/replacment is normally negotiated anywhere from 1 to 2 years. Unless it is something large and expensive and therefore defaults to the MFG, or if it is something the customer dictated with their spec (or in other words ... you wanted to use the junk so don't come after me it it doesn't last).

Since my customers are rarely the end customer, I usually work with them to come up with somthing consistent with what they are doing themselves.
 
Depending on your machine, I would think the only thing that could be completely fool proof is a vibration powered hour meter attached somewhere. Everything else seems fairly easy to tamper with.

Maybe go with every option available? PLC based, electric external, and vibration powered and the OEM can go off of whichever is highest.

Maybe have the machine email/text the run hours once a week to the OEM and watch for discrepancies?
 
I know u r the experts in the control systems i am student.

do they have any thing in place now?
that maybe could be modified or expanded upon?
completely fool proof
not even going there, I am allways amazed at what fools can do!!
 
Depending on your machine, I would think the only thing that could be completely fool proof is a vibration powered hour meter attached somewhere. Everything else seems fairly easy to tamper with.

Maybe go with every option available? PLC based, electric external, and vibration powered and the OEM can go off of whichever is highest.

Maybe have the machine email/text the run hours once a week to the OEM and watch for discrepancies?

Again, I didn't say anything about foolproof. That is why I said "Tamper Resistant" and not "Tamper Proof". I'm not looking for Fort Knox, I just don't want it to be as simple as setting the number to zero while online with the software.

Even just making it mildly harder will drastically reduce the odds of someone monkeying with it, unless they are the type that just like a challenge.
 
one thing to keep in mind if you do it in the plc and it goes south( I MEAN FUTHER DOWN THAN TEXAS LOL)you could lose your timer most panels i have external timers. you could just power it off an output in your plc when the system/process gets a run command
 
also you might want to consider an input off the timer power(from the output) to give an alarm and start a timer so you could keep trac of the hours if the output fails or your fuse to the timer blows ect...
 
Again, I didn't say anything about foolproof. That is why I said "Tamper Resistant" and not "Tamper Proof". I'm not looking for Fort Knox, I just don't want it to be as simple as setting the number to zero while online with the software.

Even just making it mildly harder will drastically reduce the odds of someone monkeying with it, unless they are the type that just like a challenge.

I think Andy was on the right track. Certainly if your machine has the ability to "phone home" data periodically, that can notify you if the total is reset and even reconstruct actual usage if it is reset.

If you don't have the ability to send data offsite, you can still store the data locally for the service tech to check. Say an array holding time/date stamps and runtime totals for the past 52 weeks. If the the total runtime is less than the sum of the last 52 weeks, something is fishy. I'd recommend that you don't actually perform this check in code, just have the data to review if there is an issue.
 
completely fool proof is a vibration powered
what if this a truck monted system leased by the hour and the driver eats his lunch in the cab and leaves the motor running and the machine on but not running?
"fool proof". lol
 

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