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Old February 7th, 2018, 05:27 AM   #1
Ronnie Sullivan
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Ingenious programming.

The title might be a bit grand but I came across a program written over 30 years ago by the factory engineer (long since retired) and marveled at his out of the box thinking.

The machine was a sort of storage and retrieval system.
Freshly made bricks were transported by a overhead crane into a drying warehouse and stacked in rows.
It kept tabs on when bricks and where bricks were dropped and which ones were ready to be brought out and packaged.

All this was done automatically and it hadn't faulted in all those years.

At some point, they needed a method to retrieve rows of bricks manually.
The system didn't have an HMI so they had to guide the crane by hand
to the appropriate row (there are hundreds of rows) by eyesight and get them that way.

The engineer solved the problem by fitting a metal number keypad
But this keypad was not designed for this. I think it must have come off a door entry system or something.- He had butchered it so that each number had a seperate input to a seperate plc.

When they pressed a number, the separate plc pulsed an output corresponding to the number, into the main plc's input.
A green light came on to say it was ready for the next number and when they had done they pressed send or recieve
And the crane set off in auto mode to the correct row.

Nice.

I am in the process of retro-fitting a new plc and of course a shiny new HMI
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Old February 7th, 2018, 07:50 AM   #2
jstolaruk
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Those are fun (ASRS, automatic storage and retrieval system). I've done a few of those, the first was with a A-B PLC-2 circa 1990; no hmi, just push buttons and lights.
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Old February 7th, 2018, 06:18 PM   #3
JaxGTO
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I ran across a case packing machine for high explosive bullets once that was 100% pneumatic logic. A panel covered with air relays and air timers. A bunch of airs lines to program it. Was fascinating to watch.
Met the guy who 'programmed' it a few years later was 82 and still working for the machine builder.
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Old February 7th, 2018, 09:56 PM   #4
Geoff White
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"Ingenious programming" is code for "Future Nightmare for Someone Else"

I pity the poor fool who has to modify my DodgyNet synchronous serial data transfer system that used conventional I/O.
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Old February 8th, 2018, 04:37 AM   #5
Saffa
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Whilst not fancy and more along the line of Geoffs nightmare, I came across some wastewater pump stations in a rural north island town here in NZ that had all their control logic done with discrete ICs on prototyping breadboards. I think some old retired university professor must have built them for the council. They did duty rotation after each start, rotation on pump fault or if taken out of auto etc. Very clever but also a bit over the heads of the local Sparkies!

I was asked to try fix one which was no longer doing duty rotation... was quicker for me to replace it with a Zelio and program on site than try to fault find that custom PCB!
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Old February 8th, 2018, 08:16 AM   #6
cardosocea
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Quote:
Originally Posted by Saffa View Post
Whilst not fancy and more along the line of Geoffs nightmare, I came across some wastewater pump stations in a rural north island town here in NZ that had all their control logic done with discrete ICs on prototyping breadboards. I think some old retired university professor must have built them for the council.
Around 2012/11, I was upgrading the control system of a winch with an electromagnetic brake that was also to be upgraded.
The brake panel was pretty much the same as the previous one, full of PCB's and an actual electronic schematic of the PCB.
Wherever there used to be a chip that wasn't made anymore was a little PCB on top with a chip that did the same function or a couple of chips to do that function.

I would dread having to troubleshoot that thing I'm an electronics engineer. LOL
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Old February 8th, 2018, 09:27 AM   #7
jstolaruk
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Quote:
Originally Posted by cardosocea View Post
Wherever there used to be a chip that wasn't made anymore was a little PCB on top with a chip that did the same function or a couple of chips to do that function.
Early in my career (mid 80s), this was not uncommon. Even new stuff from the factory.
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Old February 8th, 2018, 09:32 AM   #8
Contr_Conn
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I recall in late 80s we were trying to retrofit old tractor assembly line that used dials from rotary telephones to call a specific cabin type. Dials where connected to the PLC input module.
They even had few spare telephones sitting in crib in case they need to replace a dial.
End user liked these dials and would not accept anything else.
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