What's the most annoying PLC problem?

[mk42]

Our systems have historical data servers. And I have yet to find a customer that doesn't let you debug a program online. Is not like your hurting anything you are just monitoring.

Also sometimes the bug is obvious when you look at the logic, and just reported to engineering for a fix or fix it yourself.

So report steps taken by operator to create the issue. Then look and the logic conditions, and see how to prevent it.

Most machines have steps to follow for the operator in these one offs operators have done their own sequence that wasn't predicted in the logic to prevent an issue.

I agree that going online and monitoring is a relatively low rsk activity, and few customers would object to it.

The trick is when it comes time to testing the changes. I've had plenty of times where I sat on the plant floor for hours waiting for a break in production that never came. More and more plants (at least in my neck of the woods) are running 24/7, and finding ways to work through breaks. If you're lucky, you can charge for that waiting by the hour.

 

[Epy]

Most annoying problem for me so far is having to deal with the other integrators in town when they're doing the programming for one of our measurement skids (as mandated by customer).

Our measurement skids are small so basically the other integrators think it's an easy project to break-in their brand-new, untrained people.

After years of dealing with this, we decided charge customers as if we did the programming ourselves regardless because the idiots we get can't follow clear english directions about what the skid needs to do and how to calculate different things. We spend just as much time correcting their mistakes as we would doing it ourselves.

 

[ceilingwalker]

Customers with unrealistic deadlines, with minimal information. At project completion is when information I should have had at the beginning of the project, flows from mouths.

 

[AustralIan]

Not being able to use text based merge/compare tools on PLC code, without spending 15seconds exporting first.

 

[Peter Nachtwey]

Wow, here comes a RANT.

I'm a PhD student and for my research I need to do some short interviews with people who use PLCs on a daily basis to determine the most common problems, software issues, etc. Any ideas for conferences, trade shows, websites, etc. where I could find some friendly folks willing to complain for 15 minutes about their biggest problems on the job?

I don't program PLCs often but I may be just the person who want to talk to. I hate programming PLCs because:
1 Most of awful editors. Most make me use the mouse way too often. This means I must take my hand off the keyboard to grab the mouse and then move my hand back to the key board. I am a long time assembly language and C programmer. I like a good editor.
2. Some PLCs have glaring flaws. For instance the Step7/S7 doesn't have indirect programming in ladder. Mitsubishi's function blocks allocate data backwards from high to low instead of the intuitive low to high. The AB COP command is not smart enough to know if you are copying an array up one element. It should know it is writing over itself and copy the data starting from the back.
3 The choice of PIDs are limited and often are not implemented correctly. Some are too hard to setup. There are lots of threads about setting up an AB PID. This is an indication that it wasn't obvious.
4. Getting back to the editor. It is difficult to see more than a few rungs of ladder whereas I can see 40-50 lines of code.
5 No real time trace. A real time trace with event trigger like a logic analyzer would be great.
6. Many PLCs have kludge Ethernet interfaces. The AB MSG block is the best. Automation Direct is a close second. To many other PLCs use a socket interface. It may be flexible but few of my customers can implement them so I must help. It is the fact I must help my customers with PLC coding that p!$$e$ me off.
7. I/O is slow and non deterministic. Actually this is good for me because people that try to do motion control applications fail due to these reasons as well as not having the right PID.

 

[Epy]

Customers with unrealistic deadlines, with minimal information. At project completion is when information I should have had at the beginning of the project, flows from mouths.

Yes. Love that last second "oh you made it so it works this way? we wanted it to work this other way...even though we never said anything about that"

 

[Aabeck]

Yes. Love that last second "oh you made it so it works this way? we wanted it to work this other way...even though we never said anything about that"

I had one customer that I learned to ask very specific questions and get detailed spec's on how something was to run, and inevitably at commissioning as soon as it was started they immediately jumped in "Oh that can't happen until after xxxxxx happens."

Most of the time it was an involved program change and a couple of times meant adding I/O to the line they forgot to mention.

But they paid well, and always on time.

 

[cjd1965]

The most annoying problem is a system with mechanical or basic process problems combined with a customer that wants you to "fix it in the code".

This, this and this

 

[DwSoFt]

I had one customer that I learned to ask very specific questions and get detailed spec's on how something was to run, and inevitably at commissioning as soon as it was started they immediately jumped in "Oh that can't happen until after xxxxxx happens."

Most of the time it was an involved program change and a couple of times meant adding I/O to the line they forgot to mention.

But they paid well, and always on time.

They best is when you know the process and suggest improvements which require added devices and they say no. Only to have startup not go well and then they want it now...
But yes they usually pay well as well... lol

 

[robertmee]

My biggest pet peeve is management trying to take away an operators ability to think and do their job. Stupid alarms or lockouts or stripping down functionality because they are afraid their operators aren't competent enough to run the machine. In my experience give the operator as many tools as possible and they will make the machine run better than any amount of situational code.

 

[DwSoFt]

That's when they need to wake up and get better operators... Lol

 

[bitmonkey]

Let me condense this thread for you. The BIGGEST problem in industrial automation these days is we have too many people with PhDs running around, who have no friggin clue what it takes to run a successful business, dictating to us how to "improve" the process with their FASTERBETTERCHEAPER mentality and absolutely no regard for the unintended consequences of their decisions.
No disrespect, you did ask.

 

[John Morris]

Let me condense this thread for you. The BIGGEST problem in industrial automation these days is we have too many people with PhDs running around, who have no friggin clue what it takes to run a successful business, dictating to us how to "improve" the process with their FASTERBETTERCHEAPER mentality and absolutely no regard for the unintended consequences of their decisions.
No disrespect, you did ask.

And now you know WHY I got out of manufacturing!!!!!!!!!!

 

[John Morris]

Most annoying PLC problem? Customers with their annoying lists of changes.

With no clue how long it takes to make those changes. They think its like flipping a switch and cannot (and don't want to) understand what it takes to make those changes. They just want you to stick to the unrealistic time frame they have stuck in there head.

My apologies, i am usually jovial and light hearted in my replies. but this one happen to strike a nerve.

 

[James Mcquade]

My biggest complaint, BUBBA !!!

He looks at the code and doesn't even take the time to understand what's going on, let alone even read the rung comments, and modifies the code to the point that the machine doesn't even work correctly and he's happy with it!!

he's also notorius for calling at 2 am with a problem that he created and wanting you to fix it, then it's your fault for what happened.

james