Urgent help needed. What makes a PLC a PLC?

Well I find myself once again in the need of information from the participants of this forum. What makes a PLC a PLC? We have a control panel that once used "markload" alternating relays, timers and analog signal conditioners. Over the years it evolved to a "programmable relay" to perform these functions, specifically the "Moeller" smart relay. I believe this relay is the exact same unit used for Allen Bradley's "pico". My problem is that a specific customer's engineer has declared this relay a PLC and as such falls under their requirement that "all PLCs be Allen Bradley SLC500".

I know the functional differences between the two but what documentation / argument can be provided to convince him that a programmable relay is not a PLC?

I must meet with him this Thursday 10/16 to plea our case.

Thanks in advance for any input.

IMHO
THe Moeller "Easy" and the Allen Bradley "PICO" are both PLC's (they are essentially the same thing)
They are Programmable
They use ladder Logic
They Control circuits.

That said, I thing that the stipulation that All PLC's be AB SLC 500 is ridiculous..
Tell him to be reasonable.
Show him the $$$
Good Luck!

If he is not reasonable, and doesn't care about the dollars, he has two options....

Hey, he can either pay for the more expensive solution, hardware and software conversion time OR

Put the Smart Relay into a small plastic box of its own, paint it black and call it a dedicated industrial microprocessor or controller. (ie Black Box). And reassure him that if the place ever burn't down he should always be able to find it ....

Boy, have I met my share of "specific customer's engineers", mostly mechanical, demanding SLC500s. Only because that's what they remember from their college Automation lab...

There is nothing wrong with SLC or Allen-Bradley in general. There is something wrong with those engineers...

I can see them saying that "all PLCs be Allen Bradley", but the addition of "SLC500" is just plain ignorance on their part. The spec got written years ago, and was never updated.

You may want to print out THIS PAGE from Moeller where they call it a "control relay". They say it "combines all the performance features of a PLC", but do not say anywhere that it IS a PLC, which it isn't IMO.

Allen Bradley won't help you much. The main page for their Pico starts off with the question "Is it a PLC, or is it a smart relay?", yet the question never gets answered... utoh

It's in the "Programmable Controllers" category of their directory, though I feel it should go under the "Relays, Timers, and Temperature Controllers" heading.

Give 'em two prices and let THEM choose. Cheap with an Easy, and expensive with a SLC500. If they want a SLC, give them a SLC... :nodi:

beerchug

-Eric

You might ask them what makes a car a car and a van a van. After all, both have four wheels (and, of course, a spare one ).

Devil's Advocate here.....

My site is all Allen Bradley PLC 5 and SLC. From our perspective as an end user, we cannot have all the hardware and software for all the different things each OEM thinks we should be using. The more expensive SLC will be cheaper in the long run than a PICO type device if everyone on site is already using RSLogix 500 and SLC processors. I think he is just trying to avoid the PITA of needing the interfaces, extra spare inventory, etc. associated with trying the latest and greatest new little smart relay toy thingys. Let him know the extra cost and I'm sure he'll go for it.

Angels's advocate here

Its a question of who will be responsible for the equipment, once it is taken over by the customer but still within warranty.

If it is accepted by the customer that he takes over all responsibility if he even touches the equipment, then he should have it his way. He can access the PLC, and it is the PLC of his choise. The supplier should then only be responsible for defective parts.
Of course, the customer must accept to pay for having the equipment customized to his specs.

If not, the customer must accept and understand that he is purchasing a standard type of equipment.

Both ways have its merit.
The first should be applied if the equipment can be expected to be modified over its lifetime, or if the equipment should interact closely with the customers existing installation.
The latter should be applied if the equipment is functionally stand-alone and/or a highly standardized device.

HNC 101

Well, you see, an EASY/PICO is a Unitary PLC, while a SLC500 is a Modular PLC and the SLC 5/0x's are Rack-Mounted PLCs....

And we all thought those terms were useless...

I think we've finally found a workable definition of the difference between a PLC and a smart relay.

If g.robert's customer is willing to pay the price difference between the two products, then the Pico is a PLC.

If g.robert's company is locked into a fixed-price contract , and they based their price on the cost a Pico, then that puppy is a smart relay.

I agree. If you knew about the spec in the quoting stage, it shouldn't be a big deal. The playing field should be level on that front for all who bid.

It appears that this is not the case. If you based your price on the smart relay, say it right now and charge extra for the SLC. I can understand why the customer wants consistent hardware, but he needs to tell you up front.

I am in the market for a new minivan. What would the dealer say, if after closing the deal, I said, "My spec calls for a DVD entertainment center, put it in for free."

but what is the difference ???

hi every body ...

in my opinion , i dont think that a PICO controler is a PLC at all
cause it doesnt has the same set of instruction of a "plc" even if the price is nearly the same but SMART RELAY doesn't provide functions like MOVE -MATH - convert....etc etc .. AM I RIGHT ?

BEST REGARDS.KUMAR (SHEERS)

I can see from an end user's point of view, it is a progradamnable device. Which means new cables, software, documentation, and version control. Since it has all the headaches of a PLC, it is a PLC.

In other words- if it looks like a cat... (sorry Pierre)

First of all Pico like Zen like Easy are according to my opinion PLCs
but I have in front of me Omron ZEN book and its writen "programmable relay"
Here the front of Omron Zen Catalog
Its Writen "programmable relay"
I hope you will get it on time.
Robert good luck

[COLOR=blue]g.robert[/COLOR] said:

My problem is that a specific customer's engineer has declared this relay a PLC

Click to expand...

Dear gr, you have found a new game. The name of the game is money. We can easaly deduct from you inquiery that you have the contract but do not want to spend the $ for a real-men PLC.

Like cars, animals and drincks, there are sissy PLCs and real-men PLC

Guess what those relays are?

Then again, to open a garage door or to control a lawn sprnckler system, they can be very handy.

Negociate. Get something in return. Don't tell him he's a jerk and is a sissy-PLC-man.

If you want more buziness from him in the futur you must tell him YES this is a PLC and we will give you what you want. But get something in return. Of equal value.

The name of the game is money. Who cares what he calls this. Get some money from him to give this relay a respectable name. Anything is for sale.

When you sit down to negociate, judge the man in front of you. If you judge him an intelligent guy then speak the thruth. Tell him you have quoted this as a relay and your price is based on this fact. Show him some printout that say your are wright and some that say he is wright. Show him it's a grey zone and any arguments is speculative. Tell him exactly how much more money you want. Then the negociation starts.

If you judge him to be dumb. Anything goes.

Just remember that any bad settlement is always better than a good suit in court.