Lets do a bit of 'chest beating' for a change.

[Aabeck]

How many times have you checked for a bad fuse, found one, turned the power off and (without checking that the power was off) reached in and had your beeper go off on vibrate mode at that precise second?

Saw one leader do this, jumping a few feet, then realizing it was his beeper, looked at the number on it, smashed it onto the wall, then called his wife and scream at her to never do that to him again.

 

[Mike Lamond]

At two weeks past the 30 year mark, I can think of several high points but the last week and a half has to be the biggest. We're designing and installing a long-awaited upgrade of a warehouse automated storage and retrieval system from Allen-Bradley PLC-2 to ControlLogix and CompactLogix. This is a three or four generation leap but the legacy support for RS-232 serial and Remote I/O let us turn Phase 1 into a module-by-module changeover with no extra downtime.

We had several projects hit the design stage at the same time over the winter, so our boss hired a free-lance A-B developer to write the ladder logic conversion to my requirements. The PLC-2/30 registers were mapped to a large integer array in the ControlLogix CPU, and the array in turn was mapped to PLC-2 communications. All of the converted logic uses this array plus a parallel timer array, and don't forget to convert PLC-2 octal addressing to Logix decimal array indexing and bit numbers. In more than 1000 rungs of converted code and I/O mapping, we found just eight errors between factory and site testing.

After a successful FAT, the plant controls engineer and electrician for that area along with my boss and I started the install on Wednesday afternoon once daily operations were completed. The first step was to hang the 4-slot CPU chassis on the PLC cabinet door (the only open space!) and plug it into an internal outlet strip for power. Our first test was the serial connection to the existing UNIX workstation. It took a null modem cable, gender changer and 9-to-25 modem cable between the ControLogix serial port and the short haul modem to the control room, but the computer cleared all comm errors as if it were still connected to the 1771-KG module in the PLC-2 local chassis. Next we switched over the I/O, which came online after a few DIP switch changes. At this point, without any loop checks, the plant electrician pushed the start button and the main conveyor started, just like it's supposed to. We sent pallets all around the conveyor then switched back to the PLC-2/30 for the next morning's operation.

Thursday afternoon we ran more tests and decided to leave the new processor in place for Friday morning's operations. After that ran normally, we spent Friday afternoon trying every stupid operator trick we could think of. Along the way, we learned that the 10, 11 and 12 on the drawings and program documentation were really HEX values which explained why we saw the computer writing destination 18 for an oversized load. That forced us to go back to the PLC-2 long enough to verify that the computer was correct. At the end of the day, we committed the following Monday to pulling the PLC-2/30 out for good, installing the new 1756 I/O chassis in its place and cutting over the I/O modules one at a time. This was possible because both chassis' had 16 point modules in the same arrangement. Tuesday's operations ran on 10 1771 modules and one 1756 module. Wednesday's ran on four and seven, after which we moved the final modules, removed the 1771 chassis and move the ControLogix processor rack from the door to the empty space. Meanwhile, the remote 1771 chassis in the control room console remains until we replace it with a touch screen during a later phase.

This was one of those "Sometimes I even amaze myself" or "Some days I really am as good as everybody say I think I am" moments. Still to come are four PLC-2/16 systems, which can be done as a "nuke and pave" upgrade since warehouse can operate one pair while the other pair is shut down.

Mike

 

[RussB]

How many times have you checked for a bad fuse, found one, turned the power off and (without checking that the power was off) reached in and had your beeper go off on vibrate mode at that precise second?

Saw one leader do this, jumping a few feet, then realizing it was his beeper, looked at the number on it, smashed it onto the wall, then called his wife and scream at her to never do that to him again.

I truly feel sorry for that woman...

 

[Ronnie Sullivan]

It's like those that think is funny to bang something loud while you have your hands in the 'electrics'
They only do that to me once!
The telling off they get cures them of it for life.

But, as an apprentice........I too thought it would be funny to make a loud bang while 'the mister' had his hands in there. He banged his head - then banged mine.

 

[just the cowboy]

Did an easy one

About 20 years ago I went to a plant to introduce myself , and while I was there I was asked to look over a program that a tech was writing. He was on rung 100 something and not near complete. I asked him why he was not using a sequencer in and sequencer out instructions, and load the data for each recipe into them. He said what???? I rewrote it with him in ten minutes in 8 or 9 rungs, and showed him how it worked. They asked what they owed me and I said nothing I was here to introduce me and my skill set. I got hundreds of thousands of dollars of work from them.

 

[JaxGTO]

It makes me unbelievably happy that things like that exist. Where can I get one?



When I was an apprentice my supervisor and I were trying to find the feed for some street lighting so we could change out a fitting. We were using the site two way radio's and chattering back and forth "is that it?" "nope, still on" and so forth. Then I found what looked like exactly the one, and said "hang on Terry, I think I've found it. I'll just pull this fuse out." I pulled the fuse out and at that exact instant there was a huge BANG! as every single contactor in this massive switchroom dropped out, and all the emergency lights came on. There was a moment of silence and then someone across the other side of the plant picked up the radio and said "uh...[my name]? Maybe you should put that fuse back in."

As it turns out, power had gone out to the whole city, but as an apprentice that was one of those moments where your gut drops a mile

That's to funny! I don't know how many times I have hit test edits and then there is a loud noise. Always something else, but it keeps you on your toes.

 

[Pete.S.]

About 20 years ago I went to a plant to introduce myself , and while I was there I was asked to look over a program that a tech was writing. He was on rung 100 something and not near complete. I asked him why he was not using a sequencer in and sequencer out instructions, and load the data for each recipe into them. He said what???? I rewrote it with him in ten minutes in 8 or 9 rungs, and showed him how it worked. They asked what they owed me and I said nothing I was here to introduce me and my skill set. I got hundreds of thousands of dollars of work from them.

That's a great story!

 

[Paullys50]

I got a customer to buy me dinner.

 

[Christoff84]

My favourite is when our maintenance manager and plant manager decided to "get us into robotics" by purchasing a used robot off an injection moulding machine.

Needless to say the vendor was not very helpful and couldn't figure out how to make the machine work. The control system manufacturer wouldn't sell me the software to get into the PLC without buying their training course, etc and becoming certified. I was essentially stuck with a black box PLC doing the motion control and told there was no money to buy a new PLC/HMI. The OEM that built the machine told me it was impossible to do what I wanted as it was built to work with the injection moulding machine, that we didn't have.

Long story short, after 8 months of stress and pressure from upper management to get it going, I managed to dive into the file structure of the PLC (files were all on a removable CF card, system was CodeSYS underneath), but all the built-in routines were plain text. Some quick editing here and there under the hood and the system has been working great for years. The best part, the robot worked so well, it cut our breakage due to handling down so far, it paid for itself in < 100 days.