How much time does it to take to replace a PLC

[cardosocea]

Actually the "Fastest" way to do this job, would be to install the exact same PLC that went bad, load an existing copy of the program back into it, slap it into run and go get some lunch.

For some reason, the companies I worked at very rarely looked at keeping an eye on obsolete equipment in order to stock up on parts to be covered for a couple more years.

I find it amazing how people with MBA's fail to see the risk and cost of having to upgrade a system on the fly with the inherent loss of production in order to have a small warehouse.

I would go with Siemens... but mostly because I like it better.

 

[padees]

We have many widget makers like that around here. Most widget makers have very little capitol, ineffective maintenance personnel and heaven forbid implement a PM program.

Some widget makers have an employee that “knows” someone. Widget maker contacts this “someone”, who has absolutely no business touching this stuff. This “someone” and widget maker strike a deal. Widget maker was happy because he thought he was saving a pile of money. You know how the rest goes…

It totally depends on the widget process, documentation… as others have stated.

Some widget systems can be up and running within a few hours with totally upgraded hardware (PLC), while others may take a while.

We had one widget company that had an employee that “knew” someone. The task was to upgrade widget machine from an old Modicon to a ML1500, which he did, and did quite well. This “someone” was not a real company and never got paid because widget company owner was a crook. Well, one day ML1500 blows the base unit, and widget machine is dead in the water. Incompetent maintenance employee (who parked his vehicle backed up to the building so you couldn’t see the stolen license plate), swaps out the base unit, then manages to smoke both the new base unit and processor.

Being dead in the water, widget maker calls us. We’ve had dealings with widget maker in the past, and he don’t like to pay bills. Anyway, we go look at it. Service tech goes out, gets the story, sees the problem and can’t stop laughing. Repeat, he can’t stop laughing!

We get the new hardware and install. OK, you got the program? Umm, well, incompetent maintenance person, during his last tangle with this inadvertently overwrote the program with widget machine 3 program. This “someone” did 3 widget machines for widget maker. This “someone” was contacted, and no way was he going to cooperate unless he got paid. Well, widget maker didn’t want to pay. Said to do what you must do to get it running.

Service tech asks for documentation. No drawings, but have a print out of a Modicon program. Well, that turned out to be for a different widget machine.
So, I head there. It took a bit over a week to get widget machine up and running, with much higher production and more features. I got a lot of this never worked stuff, or we would like this…

Now they are making widgets at a much higher capacity because “someone” was only a programmer and didn’t quite understand the mechanical, but still did a pretty decent job.

Now, we know widget company owner doesn’t like to pay bills. Hopes if he avoids them they will go away. Not gonna happen. Boss man said to triik widget machine program out a tad. Telephone number password, and on the 91st power up, it isn’t gonna make any widgets. They drop the main power to the building at the end of each day, so on power up…

A couple weeks pass after D-Day and boss questions my stealth. No way is that making any widgets! About 6 weeks after this would not start up, we get a call from widget maker that don’t like to pay bills demanding the password. They found another “someone” that finally figured out after six weeks that this was password protected.

We are not budging and Lawyers on our side are in deposition mode. Widget company owner is defiant and has this other “someone” try bail him out. Didn’t work and doubt this “someone” got paid. Widget company owner finally sent a check to our lawyers that cleared. As far as I know, I made up a package for widget company with a lot of sunshine so they can make widgets again.

 

[Steve Bailey]

Now, we know widget company owner doesn’t like to pay bills.

You're more tolerant than I would have been. I always took the attitude, "fool me once, shame on you; fool me twice, shame on me".
Now that I'm mostly retired I'm sitting back waiting for a couple of former customers who only called when things got to the crisis stage and were notoriously slow to pay. It will be so sweet to say, "sorry, I'm retired".

 

[sparkyinak]

Great feedback! Keep it coming

 

[padees]

You're more tolerant than I would have been. I always took the attitude, "fool me once, shame on you; fool me twice, shame on me".
Now that I'm mostly retired I'm sitting back waiting for a couple of former customers who only called when things got to the crisis stage and were notoriously slow to pay. It will be so sweet to say, "sorry, I'm retired".

First time I've ever worked with this widget company. Boss knew the potential outcome but went ahead anyway. They make widgets, but also do a lot of chemical repackaging for a major auto parts that sponsors a major Top Fuel FC, also NASCAR. There are bars and steel gates on every door and window there. That's just to keep the crooks out. Was outside one day not concerned and the cops swooped in on this house across the street and hauled a guy and gal off in cuffs. Hookers all over, and gunfire is common. Yeah, a lot of fun!

Didn't ask if I should have gotten hazard pay. Ha!

 

[sparkyinak]

All valid points here and no one is wrong. There's a cost with long down time but costs for stocking expensive parts that you "may need one day" for long periods of time. Capitalism in general is not being the most efficient, it's about the most profits....

 

[AxelBerkling]

There's no excuse for not having backup of all the PLC programs in your plant. Even in the worst situation that there's no controller on the market that can load the old program you'll still be able to do reverse engineering.

 

[cardosocea]

There's no excuse for not having backup of all the PLC programs in your plant. Even in the worst situation that there's no controller on the market that can load the old program you'll still be able to do reverse engineering.

This is not as simple as it sounds... some companies charge extra for the software files with comments and not fully blocked. Companies fail to see the value in it (because it costs extra and the machine is bought to do what it's supposed to do) and don't pay for it.

Now taking an upload from a PLC and reading through it to try and understand it may be simple on small machines, but not really usual overall. Add that to programs that are now compiled and it becomes near impossible to reverse engineer that.

 

[Andybr]

Our modern systems are usually based around large PLC's which each control a particular area of a line. These are completely network accessible allowing almost all updates to be done on line, usually during production. We do, however, have many "legacy" machines with small stand alone PLC's and these do occasionally fail and require replacement. This is usually done by replacing the original PLC with distributed IO and absorbing the functionality into the main area controller. Once this is done the machine becomes accessible to our SCADA system and can be maintained over the network so there are definite advantages to us in doing things this way.