memory for plc's

snyder88888 · Jan 17, 2006

what type of memory do plc's typically use EPROM, BUBBLE, UVPROM ECT.

TConnolly · Jan 17, 2006

snyder88888 · Jan 17, 2006

Which Is Most Typically Used In This Day In Age

BobB · Jan 17, 2006

Still a lot of battery backed RAM around as well.

Many PLCs are using flash RAM these days - battery still reqired to hold up the data area if required.

jvdcande · Jan 18, 2006

snyder88888 said:
Which Is Most Typically Used In This Day In Age

This question is almost impossible to answer. Every brand has his preferences. A user primarily using brand A will have a different view than a user primarily using brand B. The only way to have a complete answer is to investigate the data from all brands. I do wish you a lot of luck if you were to engage in this work. Some years agoo I've seen a list of the brands and families available in Belgium: over a 100 different names.

I use three brands (Siemens, Allen-Bradley and Omron) totalling 6 families (Simatic S5, S7-200 & S7-300, Allen-Bradley SLC & CompactLogix and Omron CQM1). For these I use EPROM, EEPROM, Flash RAM and MMC cards. Pick your choice!

Regards,

Peter Nachtwey · Jan 18, 2006

Not mentioned.

http://www.metering.com/archive/023/54_1.htm

BTW, bubble memory went out in the '80s. It is surprising that someone even remembers that these existed. I wrote a driver for a Intel bubble memory. We used it once or twice. It was a waste of time.

Ken M · Jan 18, 2006

Peter

Like you I was surprised to see the reference to bubble memory. Now if ever there was a solution desperately looking for a problem, that was it. I think the only people who took it up in any quantity was the military - zero power required for memory retention, immunity to RF corruption etc. But I think even they balked at the prices.

Ken

Andybr · Jan 18, 2006

I seem to recall Bubble memory was used in the Rosemount System 3 DCS. They bought our old cards back as spares when we decommissioned our last system some years ago.

Rod · Jan 18, 2006

Older Fanuc CNCs - mid '80s used bubble. Many are still in service.

Install a rebuilt, wipe mem, search for bad 'blocks', reload and go. I think the chips are still available for an arm/leg 64s and 128s

I prefer ferrite wire core mem, longer lasting

Rod

RMA · Jan 18, 2006

I prefer ferrite wire core mem, longer lasting

When I think back to how many driver transistors I changed on DEC PDP11 ferrite core memory boards in the '80s and 90s, I could almost be tempted into becoming a Bubble fan!

TConnolly · Jan 18, 2006

Rod said:
I prefer ferrite wire core mem, longer lasting

We used to have some DEC PDP 8As running three manufactuirng cells. Each had 32K of ferrite wire core memory, 4 17x10 boards, 8K each, double sided, weighing in about 6 lbs each and costing several grand apiece. The DEC PDP was slow, heavy, and energy thirsty, but it never forgot.

The trusty PDP took us to the moon and back.

Rod · Jan 18, 2006

The PDP8(11) was used in the Kearney-Trecker horizontal mill. I'm thinking '74ish.
I rarely had probs with the DEC or it's memory, per se. But the hard drives were a ^%@$#.

2Meg 14" platter - 208 3phase drive motor - if my memory core is correct LOL!

I'll bet RMA will chime in and correct me.

Ever work on ECL or RTL logic boards?
Most new-hires probably haven't seen TTL>CMOS

I thought the IBM 560 was used for lunar landing calcs. I had to oversee 4 of them and they ran - cripes! wasn't ADA, but a symbolic language called...

I watched a guy code a 64x64 FFT transform on one line, impressive!

Oh well,
Rod - I better get back to my wire-wrapping

TConnolly · Jan 18, 2006

It could have been the IBM560 doing the calcualtions but I believe it was the DEC PDP that was controlling the rocket. I'll have to check on that.

edit:
OK I stand corrected on that. It seems that the command module and landing module had a custom computer constructed by MIT. It had 4 K of ferrite core memory, but it also had some 74 K of hardwired memory (this was the program and constants storage area) - changing the contents of this memory meant physically rewiring - which seem extreeme to us now, but it was apparently fortuitous because the computer rebooted several times as Apollo 11 was landing and picked up right where it left off.

Terry Woods · Jan 18, 2006

On the first trip to the moon, the computer croaked just minutes before landing. The first moon landing was a seat-of-the-pants kinda thing.

I can hear them now... "Oh $hit... Oh $hit... Oh $hit... Anybody got a Triple-A Card?... Oh $hit... Oh $hit... Oh $hit..."

TConnolly · Jan 18, 2006

It wasn't a total croak. It suffered from several overflows from the Radar system and auto-rebooted several times. Its a testament to the design of the computer that it was able to maintain the most critical tasks of engine control even through the reboots.

http://www.abc.net.au/science/moon/computer.htm

memory for plc's

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