GE PLC's with Y2K issues

greenspun.com : LUSENET : TimeBomb 2000 (Y2000) : One Thread

http://www.gefanuc.com/y2k/109-9070.html

http://www.gefanuc.com/y2k/108-9030.html

http://www.gefanuc.com/y2k/102micro.html

A few excerpts.

2-digit year rolls over to 00. Customer is responsible for taking precautions to ensure that any application program that utilizes the two-digit date code interprets it properly.

Date rolls from 12/31/99 to 12/32/99, then corrects itself on January 2nd on versions: xxxx

The PCM transitions from year 99 to 100 (instead of 00). Within the minute, the PCM will resynchronize with the PLC CPU with the correct year:

I seem to remember a few pollies claiming that y2k issues in PLC's were just a hoax. Hmmm, GE doesn't seem to think so.

-- John Ainsworth (ainsje00@wfu.edu), November 17, 1999

Answers

Nope, I said and still say that a PLC that quits on rollover is unheard of. Those don't quit, they just give an odd date or take a minute to reset themselves.

Still looking.

-- Paul Davis (davisp1953@yahoo.com), November 17, 1999.


And what is the result of giving an "odd date" to the "application program that utilizes" it? What is the effect of a re-set??

Feel lucky?

-- King of Spain (madrid@aol.cum), November 17, 1999.

..what is a PLC? My brother-in-law works for our city owned and run electrical system which buys from First Energy in bulk and then resells to us citizens. He has told me several times in our several discussions that we will be okay because we don't have too many PLC's!

-- Vern (bacon17@ibm.net), November 17, 1999.

King of Spain, You asked "And what is the result of giving an "odd date" to the "application program that utilizes" it? What is the effect of a re-set??"

As you can imagine we use quite a lot of PLCs in our power stations, including a few GE ones. We have no applications that actually use any calculations from dates supplied by a PLC. If you could provide an example of an application that does use a PLC date in calculations then it may be possible to answer your question. However there are some applications that do use PLC supplied dates and times for time tagging events, and in these cases the events may not be recorded in the correct order.

I have looked through the lists of PLCs provided, and I can not find any PLCs that would "reset" on the roll-over, but there are some that will reset there own internal clocks to an arbitary date should the power supply be removed. If a true date/time is required to be output from these PLCs then there internal date must be reset manually.

Not one of the listed PLCs will fail on roll over.

Now KOS, I have a question for you... Does your mud wrestling proposition actually work? And if so, which of our forum regulars do find is the best mud wrestler? :)

Malcolm.

-- Malcolm Taylor (taylorm@es.co.nz), November 18, 1999.


Malcom, thanks for your informative commentary regarding PLCs. I realize that anyone who has ever actually gone through the painstaking task of locating and checking out their embedded systems has usually reported that there was nothing that would have been a "showstopper" -- at worse, a bad date that was never used.

But let's remember: The predicted percentage of embedded problems has always been real low -- like 1% to 3% or thereabouts. So, I think that it still gets down to how "lucky" we feel when it comes to embedded systems, because obvously they have not all been checked.

In answer to your question: Gentlemen never tell. (I don't know how that would apply to me, but it sure sounds good to say it.)

-- King of Spain (madrid@aol.cum), November 18, 1999.


I don't know if I agree on this one. I got into the computer game because i knew PC ladder logic many moons ago (ok about 12 years) we used hour counters all the time to open valves and cool down furnaces. Some cycles lasted for several days. While to be honest We still counted down from hours we had investigated preprogramming heat cycles to start on a Sunday night or Monday morning so when first shift came in monday the cycle would have been started. You're telling me know one does this? I don't think so. Lots of companies must be using PLC Ladder logic with dates. I think it would be stupid not to. The other wierd think was that some of these logic controllers ran a Base 6 counting system. It was a pain so many probably just used the date. Honeywell made the ones that used base 6.

-- (computerman@not.now), November 18, 1999.

The following is from the Allen-Bradley Y2K Issues List. Can someone issue #2 statement that implies the following PLC models can cause a process that relies on the date to shutdown if not powered up during the leap year change on February 29. Am I reading this correctly? Caps and quotes below are mine for emphasis::

Issue #2

Model Nos. 1785-LT4 1785-LT3 1785-LT 1785-LT2 6008-LTV

The processors pass all the tests except leap year in powered down mode. The processor, if set to 2/28/2000 and powered down through the date change, will power up with 3/1/2000. If the power remains ON through the date change, the correct leap day is displayed. This is not unique to the Year 2000. Expanded tests shows the same results for 1988, 1992, and 1996. The important thing to remember is that this does not stop the processor from running "UNLESS" the application code relies on the date for execution. There will be no fix for these processors.

-- pho (owennos@bigfoot.com), November 18, 1999.


Moderation questions? read the FAQ