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Old January 11th, 2023, 07:13 AM   #16
Manglemender
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In the dim and distant I worked as a maintenance man in a plastics factory and my first interractions with PLC's was AB PLC2 systems programmed with the big old Grey Goose terminals. I only did backups and restore lost programs on those but we also has little Mitsubishi PLCs with a hand held programming terminal where you enterred instructions one at a time in STL.

All of the PLC gear was infinately preferable to the older machines built with sequence relays that made use of make before break contacts and timers all over the place. Fault finding on those was a complete nightmare as a machine might drop out of sequence only once or twice a shift so you ended up sitting in front of the panel following the sequence with your finger and trying to see which relay dropped out or didn't pull in. No wonder I haven't got any hair!
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Old January 11th, 2023, 07:22 AM   #17
parky
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Yeah did many on those one instruction at a time, some consoles like the Texas instruments ones were built like tanks, after carting one of those from the car park to plant you ended up with arms as long as a monkey.
Floppies only, so sometimes you had to insert the second of the operating system for certain functions, wait a few minutes before you could do anything. I do remember my first laptop a Zenith with a floppy drive, blue mono screen, load the first two floppies for the OS cost about 2.5 grand in those days, first ide was OMRON on that. Then we really went to town another Zenith with a 10mb Hard disk 4mb of ram wow.
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Old January 11th, 2023, 08:00 AM   #18
JohnCalderwood
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I do recall in the late 80s/early 90s (dim and distant memory) we were asked (in our own factory) to replace a Diogenes DCS system (jumpers in electronic drawers, and a hard-wired mimic on the whole wall of the control room, with the panels behind, and lots of pneumatic logic too) with a PLC5 upgrade of it. The programme logic was printed out on good old green computer paper, and the manuals that went with it.
We spent many months with the retired electrical engineer on site going through the logic and trying to write it all in ladder logic.
We got there eventually and the replacement worked for many years until the factory was closed.
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Old January 11th, 2023, 08:24 AM   #19
forqnc
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Baptism of fire introduction to PLC's was in the late 80's, as an electrical apprentice. Older guys didn't like the flashing lights on the handheld units, so I was thrown in the deep end to figure out what was going on. These were OEM bought machines which came with whatever PLC the OEM wanted to install. Frustrating at the time, but introduced me to a world of different instructions and how to accomplish the same task different ways on different manufacturers.
Fast forward to the late 90's and the company I worked for bought a 40 year old 1,000 ton Injection Molder. It had logic boards with wires soldered and jumpers between boards. Luckily the machine ran solid for 2 years, so we had an idea how it was 'supposed' to work. After a 2 day downtime, during peak production, I was granted my wish to replace the logic boards with an Automation Direct DL405. A 2 week fun project, machine was still running when they closed the plant 20 years later.
Oh, and the 2 day downtime troubleshooting problem was due to an operator had adjusted a pressure switch. So when the mold came up together, pressure would build up, then when the machine was ready to inject, the pressure dropped off, shutting the machine down, with no indication of why.
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Old January 11th, 2023, 08:56 AM   #20
cardosocea
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Does replacing Rockwell with Codesys count?
Yes.
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Old January 11th, 2023, 11:28 AM   #21
Tom Jenkins
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In the late 90s, I replaced a pneumatic control system for five 2,000 hp engine-driven blower systems at a wastewater treatment plant. We used Square D Symax PLCs, now themselves obsolete, and a DOS-based SCADA system.

I don't remember how many pages the control schematic spanned, but the panels for each blower were about 20 ft. long. They were so detailed they actually had pneumatic relays monitoring thermocouples at each exhaust valve. I am still in awe of what those old pnematic control systems were capable of.
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Old January 11th, 2023, 11:38 AM   #22
parky
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I looked at a system for gas supply in the 80's, there was a room full of panels probably about 15 2.5 metre full height rittal panels, these were full of relays I mean full, ironicaly, there were broken matchsticks all over the panel floors, it was explained to me that the engineers used them to force relays to get things going, it was against the rules for visitors to take any things like matches, lighters or any source of combustion items through the main gate.
We did not actually get the job of replacing them as it was on competitive tender.
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Old January 11th, 2023, 01:07 PM   #23
Robb B
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My first real introduction to PLCs was 2009 (as a second year apprentice) when the company converted a railway tie treating system from pneumatic controls to digital. We did all the wiring and PLC installation, using the second system as a template to convert the first (it already had a PLC and logic). I/O order was different and the first system had a touchscreen with no physical buttons, the existing second system had a mimic-board with indication and control buttons. Lots of mapping HMI in/out, and copying then modifying the second systems logic to work on the first. Took me a few weeks to get it working to the testing point, but it's been pretty good ever since. I still work on it regularly and am sometimes confused as to what I did back then!
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Old January 12th, 2023, 04:39 AM   #24
cardosocea
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Quote:
Originally Posted by parky View Post
I looked at a system for gas supply in the 80's, there was a room full of panels probably about 15 2.5 metre full height rittal panels, these were full of relays I mean full, ironicaly, there were broken matchsticks all over the panel floors, it was explained to me that the engineers used them to force relays to get things going, it was against the rules for visitors to take any things like matches, lighters or any source of combustion items through the main gate.
We did not actually get the job of replacing them as it was on competitive tender.
This reminds me of an industrial oven in one of the first places I worked at. The control panel for the thing was 15 to 20 meter long, but a lot of the contactor relays (not relays, actual contactors) weren't doing anything.

When I asked why so many relays, thinking it was a redundancy of some sort, I was then told that the oven was bought and the son of the owner had seen in magazines remote monitoring of plants and demanded to get remote monitoring of the oven in the office building. Their solution? Replicate a lot of the control relays for remote display and run three massive multicores and install a separate control desk at his office.
That was only found when the panels arrive. The company went under before the oven actually worked and it was maintenance that got it started.

The troubleshooting method for that system was also interesting... the most experienced electricians would just walk along the panel listening to the relays clicking... if they noticed a slight fast chatter, they'd open the door and replace the contactor commanding the "chatty" one.

The other funny thing was that the electrical drawing for the panel was a roll of about 15 to 20 meter composed of taped together A3 sheets. The previous engineer inspected the panel and glued the drawings together so that if the drawing was laid out on the floor the sheet in front of the door would have the relays inside that section. LOL
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Old January 12th, 2023, 05:05 AM   #25
Manglemender
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Quote:
Originally Posted by cardosocea View Post

The troubleshooting method for that system was also interesting... the most experienced electricians would just walk along the panel listening to the relays clicking... if they noticed a slight fast chatter, they'd open the door and replace the contactor commanding the "chatty" one.
I remember this too and have done it. The armatures in the contactors have a shading ring that encircles the open ends for eddy currents. These were often cast aluminium that would crack and break leading to chattering and occasional contact bounce, which, in sequnce relays, becomes an intermittent fault.

Nick
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Old January 12th, 2023, 05:23 AM   #26
Harrstein
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We are currently in the process of getting the last Klaschkas replaced by Siemens. They did work pretty well, but the DOS programming is quite tricky and when you blow trough 3 CPUs in the last year, some people in management come to realize that it could become nasty if it dies forever.

We also run a complete line on Reliance Automax that really are in immaculate state. Good cabinet design helps a lot.
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Old January 13th, 2023, 02:19 PM   #27
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Every time I have to do some fault finding or setup on the older gear, I keep thinking just how much harder everything must have been a few decades ago.
Like you I started on 5/04 and micrologix bricks(dont recall exactly what model, maybe an 1100).

Eddy current clutches coupled to 3ph motors is one of the coolest things I ever encountered. Had never even heard of one, and found one on a decoiler/straightener for a press.

Besides that, I've worked on some profibus S5 systems, which were pretty crazy to me. Gave me a huge level of respect for predecessors and what they had to know to be effective in earlier generations.
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Old January 13th, 2023, 02:25 PM   #28
parky
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Just remembered I did some automation by converting some large keystone valves to automate closing interfacing with the pumps on a sewerage pumping farm this equipment must have been installed in the early 1900's perhaps about 1920, the motors on the pumps looked like open frame so you could see the windings about 8 ft tall & nearly the same dia. that was really old.
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Old January 13th, 2023, 03:50 PM   #29
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Well, let see... dating myself

1. in the late 90s, my first control project. Replace Foxboro 1A (?) and Videospec 200? with PLC+Rosemount D3. The 1A was programmed with punch card and the storage medium is like a big platter thing which I can't find a picture of on Google. Here's someone's picture for part of it: https://all-andorra.com/foxboro-fox-...control-system

2. in the late 90s, replace a GE PLC we didn't know existed until it drop dead with AB PLC.

3. recently, replaced hydraulic hydro governor for a hydro generator with PLC.
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Old January 14th, 2023, 11:59 AM   #30
Ken Moore
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I suspect the Foxboro system was not I/A, but Spectrum, Spectrum was an approved Nuke plant controls system developed in the early 80's, and had a 10 meg hard drive the size of a 1960's TV.
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