PLC program for detecting Run mode status loss

parky said:

Some PLC's have diagnostic buffers or power down/ stop routines (these detect a power loss or stop instances) and can either write error codes to a buffer or even run a short bit of code before shutting down, not sure about ML though.

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No, the Logix500 series only have a battery for memory retention, it cannot supply enough power for the CPU to keep working, even for a few hundred clock cycles.

OkiePC said:

I used to do that with Atari Space Invaders to glitch the game and it would let you have two missiles in flight simultaneously if you got lucky.

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Isn't that cheating ? lol

we're fully derailed now.

daba said:

Isn't that cheating ? lol

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If you're not cheating, you're not trying.

I owe my career to my Atari competitiveness.

I won the Asteroids contest for the state of Oklahoma and 1st prize was an Atari 400. That's how I learned about BASIC, ATASCII, sprites, bitmaps, binary, hexadecimal, Assembly Language, vertical blank interrupt routines etc.

A year or two later, I discovered girls, cars and beer and forgot about computing until I got into Maintenance Tech class.

It was pretty easy for me to pick up all the number systems and scan order basics, so I became known as the "PLC guy" due to the fundamentals I had learned as an Atari PC hobbiest.

Thanks Nolan Bushnell!

OkiePC said:

If you're not cheating, you're not trying.

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Loving it !

Many moons ago, our college bar had a pinball machine that was always breaking down, so the engineer was on-site regularly (nearly as regular as the bar customers, to be honest !).

Anyway, one day when he went back to his van to get parts, one of the lads borrowed a can of hairspray off one of the girls, and liberally coated the "tilt" pendulum with it... Of course he made sure this girl was close by when he returned, just giving her hair a spray as he walked up to the machine.

If unusual odor or abnormal noise is detected with the training machine (X/Y table, ... operation status of the PLC and program can be monitored with the personal computer screen, so if. When creating a circuit, make sure to set the mode to "Write Mode". Select from. Stored data in an EEPROM is not lost at power failure. Thank You!

If I ever detect an unusual odour at work, I always remember the saying "He who denied it supplied it", and carry on without further comment.

Getting back to the original post:
Use the first pass bit to set a retentive bit that drives an output so that if the processor goes to stop then back to run it turns an output on, will need to reset the bit either with the IDE or an input to turn it off.
Other things could be store RTC etc. in a set of integers using the first pass bit to shift the RTC values in a file & update with last first pass.
This will give you the time it went back into run at least.

OkiePC said:

vertical blank interrupt routines etc.

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VBI boo-yah!


I once wrote a program on spec to replace the aging ticker on the front of the NYSE. To make it smooth, I needed to query the VBI. That also meant my ticker rate (pixels per time) was an integral of the vertical refresh. Since the rate of quotes was stochastic but basically a constant mean, that meant if I picked one pixel rate, I would either empty my buffer or overfill it. I ended up doing the latter and throwing quotes away (who would notice?). The multiple was a small number (1 or 2 or 3, IIRC), so changing the rate did not look good.


Anyway, the funny part happened later. Before I had the VBI-driven fixed rate, I varied the ticker rate to keep the quote buffer from either running empty or overflowing. Me being a chem eng, I modeled it as a level control. I drew some help menus with a schematic of a tank (quote buffer) and a pump with a control valve (ticker rate). Now I wasn't there at the time, but my client told me that some upper-level C?O came to the demo. One of his underlings actually brought up the (by now obsolete) help menu to the show the top dog how clever this program was. I would have loved to see the look on that manager's face.