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amlutoHNSource author
Business & incomeExperience excerpt · English

Another odd observation about the industry

Another odd observation about the industry. For better or for worse, I inherited a little system controlled by a Fanuc PLC. It had a bug and would occasionally get stuck in a bad state. By some minor miracle, I managed to track down the person who had originally programmed it (now retired and moved out of state), and he emailed me a file and introduced me to his apprentice (who lives in a third state). I found a trial version of the design software, opened the file and found the bug (despite never having seen this style of programming before). Since I had no way to upload a new file (and since it wasn’t clear that uploading it without a matching outdated and not easily available copy of the programming environment would be wise), I convinced the apprentice to come visit while we was nearby for another client. He did not see the bug even when I pointed it out, but I convinced him to make the change and upload the modified file. Now the system works. …

Original discussionWater system controllers don't belong on the internet, says ex-NSA chief169 source comments · at import
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AL
aliasxneoHN

Part of my career encapsulates a period where I was a PLC programmer, installer, commissioner, and troubleshooter for massive build outs (sky scrapers, data centers, laboratories, factories). Interestingly, this was after years of teaching myself software engineering, eventually participating in large open source projects. The clash of entering the PLC world was _extremely_ harsh. Let me give an example: I once worked with an integrator who was working on an AHU feeding an extremely critical portion of a datacenter (I was a lead by this point and mostly played babysitter). During certain points of the day you couldn't open the door to this room due to negative pressure because the logic was over-ramping the exhaust fans. As I watched this contractor work, I saw him open his laptop, with Windows on it (because Microsoft has had a death grip on this industry for decades now), and proceed t…

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polishdude20HN

The best thing they could do to new PLC's would be to have the src code live alongside the firmware inside. So any new person would be able to open it and reason about it.

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spauldoHN

A microcontroller based solution is rarely a good replacement for a PLC. You can find integrators willing to come out and troubleshoot your device in the field a lot more easily than embedded progammers and vendor support is usually excellent. When your plant is down, that sort of thing matters. PLCs handle harsh environments for decades, whereas with a microcontroller all the thermal issues and power conditioning are all on you. When something fails, it's usually just a matter of pulling a spare module off the shelf and plugging it in. If that's an old GE 90-30 (a common FANUC system), it's time to replace it. You're currently in that period when the CPU has reached end of life but the modules are still supported and the vendor has an easy upgrade path. Emerson owns the brand now, and can sell you a new unit that'll run your old program with minimal changes. You can call them and get a …

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