PLC Lockout For Non-Payment

[Goody]

Well I will stir the pot a little then because I have done it twice. I have written about it here before (a long while ago)

It was nothing fancy – just a date lockout coupled with the E stop and a password protected PLC. (the first time the E stop was pressed on that date, the machine stopped and would not start again)

I also informed both customers that it would happen if they did not pay in time.

The first one did and I took the ‘time bomb’ off – the second one didn’t and the machine stopped.
When they called me, I told them it would only work when I was paid. They paid me immediately and further to this, I put another 7 day time bomb on to allow the cheque to clear.

Before you get up in arms, only the people that are directly hit in the pocket by none-payments should answer.

Both these customers were renowned bad payers; the latter was once a year in paying me and only then because they needed my services again.
This money owed to me is MY wages. I am not a loan bank with flexible repayments and interest free terms.

As for bad feeling from the customer, as far as I could tell, they were sorry they hadn’t paid me in time and promised never to do it again.
I have my suppliers to pay and my customers expect prompt payment from their customers. It’s a circle and if one of them drags their feet everyone feels it.

These customers get a first class service from me and they know it, I have worked for them since, many times.

And furthermore, I would do it again if I suspected I was not going to get paid.
It does not give my company a bad name – what are the bad payers going to tell others – ‘we didn’t pay him so he switched the machine off’ what would your reaction be to being told that?

Maybe the USA is a very litigious country but here in the UK I don’t think it would stand up in court.


And one final point - it did not cause bad feeling from the shopfloor workers, they thought it was a hoot that the machine stopped because I wasnt paid.

 

[SAK-CO TECH]

Sorry About That Steve!!

Steve, my apologies, you are absolutly correct. I meant that for Bernie as you have pointed out.

One other thing Bernie,
This also promotes bad press for you and/or your company. Been there!

Regards,
Chris

 

[SAK-CO TECH]

Goody,

Im sure that most everyone agrees with you wholeheartedly at this site but to borrow your word, we are a very "litigious" country here in the U.S.

Like yourself also, most of us have A+ reputations but I'm sure you have heard the saying "Your only as good as your last project". Some of us are in very "tight" industries (in my case the metal finishing industry) and word spreads like wildfire, whether good or bad.

There are very effective ways of collecting money other some of the other questionable way's that can only bring more harm to yourself.

This reminds me of a good lawyer joke: "Whats the difference between a lawyer and a white fish? One is a scum sucking bottom dweller and the other is a fish!"

Regards

 

[Guest]

The Devil is in the last 10%

I've been in Bernie's bosses shoes a few times, and while this wouldn't be the first feature I put into a controller, it's clear that they're not new in this business and they've tried the polite methods.

I'd use the clock in the SLC-500 to generate the "password"; maybe the product of the day and the month plus the day of the week. I've seen systems that use the sum of the CPU serial number and the date as their default password.

Make sure you have a way to burn the "post-payment" program into the EEPROM so you can turn the infernal thing off.

 

[PLucas]

I have read this thread with great interest, I think that Goody brings up some very good points especially if it is your money involved and not just your company's. Personaly I can not see any thing wrong with giving your customers an extra incentive to pay their bill's on time, providing what you have supplied has been commisioned and signed off by your customer.

It has given me an idea on how I am going to get that nice huge pay rise that I deserve - BLACKMAIL!

"Paul, have you finished that project yet?"

"Yep, all done boss, But....I want a 40% payrise otherwise it's going to stop working in 3 weeks time!"

"40% are you mad! I will give you 10%"

"10% eh? that will give you an extra weeks work out of the project"

At this point the haggling continues and I finally settle for a 30% pay rise, plus a nice new office chair!

Paul

 

[RDay]

What happens if the boss uses the 3 weeks to find another employee for 40% less than what they are paying you and he even brings his own chair?

 

[PLucas]

RDay

many thanks for bursting my bubble!

I had even picked out the chair I wanted Click here to see it

I suppose I will have to make do with my old one now.

Paul

 

[RDay]

Sorry. That was a nice a chair to. :nodi:

 

[ROVMAN]

Just a comment, Faulting a Process/PLC <for whatever reason> in a municipality aspect can get you/company sued.

 

[rdrast]

I've been deposed for the plaintiffs on two different occasions, after discovering and pointing out booby-trap code in a PLC-5 and in a Wonderware application.

Fine thing for the bean-counters to joke around about, until the subpeona's start coming.

Payment schedules should be determined contracturally, and are subject to contract law and collections if violated. If nee be, a court order can be issued to prevent an end user from operating a piece of equipment, and a sealed lockout can be placed on it.

Screwing things up programmatically, and intentionally, is bad practice. If I ever run across something like that, I disable it, and point it out to the folk at the plant.

 

[akreel]

I don't think disabling a customer's machine is a good idea. Who knows what kind of trouble you could be asking for.

But, if I wanted to encourage payment I might take another page from the Bill Gates handboook: NAG SCREENS. You could cause the startup of the machine to be delayed XXX.X seconds, while a countdown reminds the user that it's time to pay the bills. Or, you could choose a convenient time for the user to have to navigate a maze of dialog boxes like this:

"Your last pament for this system has not been received?" <OK>
"Is the check in the mail?" <YES> <NO>
"ARE YOU SURE?" <YES> <NO>
"Are you satisfied with this system?" <YES> <ABSOLUTELY>
"Would you like to play a game?" <CHESS> <MONOPOLY>

AK

 

[Vetteboy]

In event of non-payment, repossess your PLC, same effect, easy to implement.

 

[ROVMAN]

Vette,

In the state of PA. for one stste I know, you can't if its a municipality installation. They enacted laws 10+ years ago to protect the public.

 

[hickman]

This approach may be acceptable in some applications...

I don't know what your application and relationship with the customer(s) is, but I believe your approach may be acceptable in some situations.

For one of my upcoming projects, I'll be "leasing" the PLC and program to my customers. I can't go into all the details, but I'm thinking about implementing a keypad into my design. Therefore, when the customer decides that my machine is doing a great job for him, he won't forget to pay his "lease".

This isn't the typical use of a PLC, I understand. My point is that your's may be a legitimate use of a 'lock-out' feature.

There's my two cents!

 

[Terry Woods]

Well, DAMN!

This whole thread has done nothing but put a "burr" under my saddle.

I agree that the whole thing is bad policy and yet... a bad customer is a bad customer. Maybe the thing to do is to write into the contract (and it should be a written contract - not verbal) that the machine "WILL" shutdown 5-days after a payment is due if the payment hasn't been made - make it very clear right up front.

Specify that everytime a payment is made, you will pass a code to the customer which will extend the life of the process until all payments are made at which point you will pass the kill-code to obliterate the "bomb".

If the potential customer argues about it... your position could be...

"Do you (the customer) expect me (the designer/programmer/installer) to perform as expected?" He will of course say yes. "Then I expect you to perform as expected as well".

All of the cards are on the table as it were.

Of course, this will only work with those customers that don't have a savy programmer on site.

NOW, the "burr".

The "burr" I have is... How to build a "bug"... a "virus"... a "worm"... a critter of some kind to reside in the PLC.

Not that I would post such a thing... but damn... it is an interesting challenge!

I've already got an idea! Do the words cryptology and indirect-addressing mean anything to you?

Again... it's just for the sake of the intellectual challenge!

Damn! This could be interesting!

Imagine that you have an incredibly strong anti-killing ethic and, in your basement, while no one is watching, you develop the first atomic reaction... you were really only trying to find a way to irradiate some orchids to see what kind of new breeds you could get... but... this atomic reaction thing fell in your lap instead (Oooo hot!).

If this happens to happen, in terms of the "Ultimate PLC Bomb", I won't be posting it.