Processor Speed of Industrial PC

We have ordered a PLC based SCADA system for a Captive Power Plant. One of the Specification is for Industrial PC with a Processor speed of 3 GHz. Vendor agreed and got the order. Now during execution of the contract, the vendor informs that the PCs with a Processor speed of 3 GHz are encountering memory clash and hang up issues and requesting us to agree for the PC with 2.4 GHz Processor speed.

Request the Forum to give their views on the comment of the vendor.



Regards



R.Thiyagarajan

Ugh, not sure what you want here. Have you considered "underclocking" the CPU in the BIOS?

I would have to ask where the 3 GHz requirement came from. Is it really a well-thought-out requirement or is this a case where someone saw that 3 is bigger than 2.4 so it must be better?

unless you are really taxing this thing I don't see where the decrease in processor speed will be a killer.
Keith

lol, that's what happened with 80s games that used the clock as a timer.

kamenges said:

I would have to ask where the 3 GHz requirement came from. Is it really a well-thought-out requirement or is this a case where someone saw that 3 is bigger than 2.4 so it must be better?

unless you are really taxing this thing I don't see where the decrease in processor speed will be a killer.
Keith

Click to expand...

There was a time back in the 80's and early 90's where higer end computers were specified for SCADA systems. A 12MHz 286 machine was depricated when a 20MHz 386 was available. I remember specifying 66MHz 486 machines in the early 90's. Those days are behind us with modern porcessor speeds, the average SCADA system is just a box of crayons in modern computer contexts, but I think old habits persist - an engineer who specified the fastest computer he could get his hands on 20 years ago still has a tendency to specify the fastest computer in the catalog.

Today, raw Hz, MHz, GHz have almost nothing to do with CPU speed, so "Requiring" 3.0 GHz is foolish. For a long time, AMD pulled significantly ahead of Intel, without raising the clock speed, just by streamlining the CPU's, pipelining, putting in intelligent branch prediction, and high speed local cache's.

Right now, for Industrial Control PC's, I like to use a lower-speed (1.6 or 2.0 GHz) Dual or Quad core Intel Core2 pocessor. Lower power usage, lower heat dissipation, higher performance.

Speed is virtually a non-issue now, the biggest single performance hit you'll see in a HMI Client or server box, is memory. It's cheap, max it out with good quality memory sticks.

While I agree that 3.0 GHz is (likely) overkill for this application, it really doesn't take much to build a 3.0 GHz (or faster) system today that does not have issues. That is what troubles me. Memory clashes and hang up issues are somewhat vague descriptions of the problems, but I don't see how a processor running at 3.0 GHz vs. 2.4 GHz would be the root cause. Perhaps they have unstable memory that can't run at its full rated speed, but they can get it to function at a slower speed. Another scenario is that they were using a dual or quad core processor and are now finding out that their application doesn't play nice with multiple cores.

Brian