And of course the logic was inverted (signal high = off), but that was the least inconvenience. And it was near impossible to get access to measure anything. Intermittent error that only showed up at certain temperatures. Worst time I had to try and fix one of these systems were when there was a hairline crack in one of the copper circuits on the circuit board. The pins plugged into connectors that were soldered onto a circuit board. The system I remember was with little grey blocks 5mm x 20mm x 10mm, with the pins on one of the thin edges. They stacked on breakable metal rods, if one failed in the middle of the stack then you had to disconnect everything above and slide them off to change hteone that had failed. Were these MTE (I think) blocks that stacked on top of each other with screw clamp connectors sprouting all around, about the size of a cigarette packet. The strangest thing was a control system made out of logic blocks (kinda like Lego blocks) with each block having an OR-gate, an AND-gate, or a timer. We used this and an A-B T3 terminal to program PLC-2s before the ICOM software and 1784-KT card came along for the PC. At my first job in 1986, they used these to build natural gas odorizer controls for the local utility.Ģ) A Zorba portable computer with the 8088 coprocessor board running CPM/86 and UP/DOC PLC programming software. Now for the truly obscure! Has anyone ever seen, never mind recently either of these:ġ) A Sylvania PLC, programmed in SYBIL (SYlvaania Basic Instruction Language) using a rebranded Kaypro II CP/M portable. I've heard that the system will be replaced as part of a major plant renovation this year. The password was to connect Input 23 to +24vdc power. The whole system, including four AC Tech dL100 VFDs, had been so trouble free for years that they never touched it. In 2010 I got a call asking if I remembered the protected setpoint password for the aeration HMI (actually a very cheap message display the took about 700 words of ladder to be usable). I started up my last Idec FA2J project in May, 1995 for a waste water treatment plant, with one PLC on the raw sewage pump station and a second on the aeration blowers. The plant I left a year ago has an Idec FA2jr still running in a machine. They have no idea how big of a deal it is to just be handed a working project to start up a de-commissioned refrigeration system of this size. Iv already given it to them once and got it all up and running for them after they purchased the building from the old owner who stripped even the code from the PLC's and the RSV32 application from the PC and left the system unusable. Worst part is, I have their backups, ghosted XP machine and all as I used to work in this plant before it got de-commissioned, but should I really just hand it to them? They have no software, licenses or anything. They just think I can "make it work" every time! I can't believe they won't bite the bullet and upgrade. Its always a scramble when this goes down as millions of dollars of product are at risk. Iv been preaching to them for years to get something started and not to wait until D-Day because that day, I don't want to hear about it. Parts are extremely hard to get and I or they have 0 spares for anything. Loosing com cards, power supplies and such. Iv had troubles with this system over the years. All controlled by one, very old XP machine running what IM sure is a shady version of RSV32. It runs 5 glycol units and a floor temperature control system, it runs another 5 compressor system for 2 massive controlled atmosphere buildings as well as 2, 200HP ammonia compressors for blast freezers. It has an old CH30 Omron with 4 remote racks. I am responsible for an old plant that we use their CA buildings for storage.
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