Choosing a PLC Brand... 3

[cfordyce]

I am replacing an old TI-500 series PLC ('87 vintage). I am having trouble deciding on a PLC Brand to go with. Whatever brand I choose will become the company standard for future PLC applications so I must evaluate each line carefully.

The TI-500 is simply monitoring RTDs, T/Cs, Discrete Contacts (Field Alarms), and a few process pressure readings (4-20mA). The PLC does no control... there are NO output cards on the rack. But there are 376 INPUT points. The PLC is interfaced to a PC (RS 232) where FIX SCADA software is used to indicate out-of-range readings and alarms, etc. The software interface is very rudamentary right now... just a text-based array of field points in a chart on the screen, when one alarms it lights up red and is printed to a log file for history trending.

I would like to replace this software with a more current graphical interface. I have the process flow diagram which I would like to be the basis of the software screen.

Does this sound like something that I could program myself with a current SCADA package or even just a HMI software package? Or would you suggest that I have this done by someone else (I do have other projects/responsibilities)???

Who would U suggest for this??? What software would U suggest??? Any suggestions on a PLC Brand?

I have checked out KOYO series from Automation Direct... but they don't seem to have the support base up here in Canada that they have in the States... but I like the prices.. and the extensive WEB presence, etc.

P/S. I am in Ontario, Canada.

Thanks for any input here folks.

 

[jlhmaint]

allen bradly is the best in my opinion and easy to work with i will post back in a minute with a web page that has there demo for free for 30days you cant do everything with demo but it will give you an idea.

 

[jlhmaint]

http://www.thelearningpit.com/lp/logixpro.html

go to this page and click download this will give you a free demo

 

[djs]

The FIX software you have is a full featured graphical HMI/SCADA system. The exact capabilities depend on the version. If there is no control functions, then you could use a remote I/O network. Both Koyo and A-B support this. Be aware that the A-B solution will end up costing twice to three times as much.

 

[dydt]

if you are in north america...i recommned allen bradley because of its popularity...most machines being built today have A-B on it...tech. schools and colleges uses mostly A-B...

dydt

 

[cfordyce]

I think U might be right dydt! A-B is looking more and more like the safest choice in all regards.

dydt. Is that the time derivative of y by chance? Interesting.

 

[chakorules]

Agreed with everyone else. If you are designing a machine in the USA, chances are it's even spec'd by most customers that we supply machines to. A-B is the way to go. Not the CHEAPEST PLC, but the safest bet.

Chris Elston
Automation & Controls Engineer

http://www.mrplc.com

Download Sample PLC Ladder Logic Code
at MrPLC.com

 

[russdee]

I personaly use Omron, the unit is much cheaper and communications are easy. I have used AB as well. The main reason (IMHO) that AB is the defacto standard with so many plants etc. is the fact that Rockwell supplies material to the educators, therefore it is the system most are familiar with.

 

[dydt]

i can't deny i like Omron as well...

dydt

 

[robertjo24]

I have had some experience with Koyo, and so far it has all been good. Very reliable, and as you stated, the price is right. I would also look into Modicon devices, (

http://www.modicon.com).

They work well, and have a wide range of options. The web site also lists some HMI & SCADA software.
Don’t tell anyone I recommended this, but Wonderware (

http://www.wonderware.com)

has a pretty good software package.
While planning a new system, have you added any room to expand? We usually say we couldn’t possibly need this or that but two years down the road we wish we had made room for unexpected expansion. Also, have you considered Ethernet comms between devices, PLC’s, and SCADA? There is a lot available out there, and the field is growing.
What application are you planning this system for?

 

[nbucska]

The PLC is the electronic emulation of the relay logic --
i.e. a pre-WWII technology. Very simple things are easy
to program but would you try to solve a cubic equation
or a trigonometric problem with PLC ?
<nbucska@pcperipherals.com>

 

[chakorules]

nbucska,

PLC have their place, would you spend the money for PC Control that can do trigonometric for a machine that needs to turn a valve on when that photoeye is made? How do you sell that to a customer wanting to buy your equipment? If you make sales like that, I want to take some lessons

That's the whole problem. Cost! It's way cheaper to hookup a PLC for simple control. Of course if you need to do what you want to do, then you would use a PC to gather data from a PLC. PLC's are going to stay. PC Control will never take over all the controls in the world. I certainly can not justify spending $800 for a PC, $1,000 for some Scada software, my time to write some VB Code. Verses $180 for a KV Series Keyence PLC with 10 points of I/O. Or even a 32 point Allen Bradley MicroLogix 1000 for under $200. Chris Elston
Automation & Controls Engineer

http://www.mrplc.com

Download Sample PLC Ladder Logic Code
at MrPLC.com

 

[nbucska]

Hi Chris Chako...:
You are absolutelly right -- PLC is cheaper but you can get
8 bit microcontroller for less than $5.-

<nbucska@pcperipherals.com>

 

[chakorules]

That's a good point.

But can that control most industry wide standard of 24 VDC, without having to purchase a bunch more in relays and such?

I never was much of a fan for TTL logic, because of noise. I once programmed a Parker Compumotor Indexer that used TTL logic as the input/output signals, and it caused MANY RUN AWAY conditions because of false TTL inputs tripping.

I know the automotive industry would not buy into a microcontroller controlling their $10,000 a minute production line. Their specs are too stiff for Tier One OEM Machine builders.

And just for kicks, doesn't a microcontroller consist of 7400 family chips compressed into AND, OR, NOT gates? Those behave like a PLC anyway, making logic using the correct &quot;gates&quot;.

Granted the last time I programmed a microcontroller with assembly language wasn't much fun either, or maybe I should just say it's not my cup of tea, using MOV PUSH etc. statments... Hopefully they have something easier to program those $5 controllers now right? Maybe BASIC.

Chris Elston
Automation & Controls Engineer

http://www.mrplc.com

Download Sample PLC Ladder Logic Code
at MrPLC.com

 

[dydt]

Allen-Bradley for example have a PLC called &quot;PICO&quot; ...a micro PLC....you can program this PLC without buying a software...just pressing few buttons on the front and enter your logic...its so amazing how this technology can run a simple machine without a bulky panel.....

...mind you this is less that US$200 with bunch of I/O's.

i am sure some manufacturer have the same product..i do saw one from Siemens..

dydt

 

[SteveMeisel]

This sort of topic could go on forever and does almost daily in other forums.
It is just another: my plc is better than yours. Or my new car is better than your new car.
The fact of the matter is they all can get you where you want to go. Preferance is to the user. AB or Automation direct is better for me. But that is me. That is where most of my experience is at.
It would be easy for some one to say use a pc and write some vb code it is the cheapest, and easiest. Well then I could say vb sux stay away from it(only because I am unfamilair with it). They all will give you the same end result. Which brand you use is up to the user. How much money you are willing to spend or how much time you (and the company) is willing to spend on you and several other people learning it is a good question to ask.
With a good outside trainer or some time spent reading and praticing any brand could be a good brand if chosen wisely (do they offer what we need and/or desire in a plc).
I believe I have read somewhere that Automation Direct does have some support in Canada. If I find it I will post it. You should contact them directly if you haven't done so already. While I was at it I would also contact other plc reps to come in for some demos. Sounds like you may be making a decision that could have some long term effects.
As for tackling the project yourself it sounds like a pretty involved process unless you have lots of free time or the company can wait a while for you to finish the job I would seriously think about some outside help.
Just some thoughts on my part.
Good Luck,
Steve

 

[techshoot]

$0.02 worth!
In regards to the original question, I would not discount looking into Ethernet I/O and other &quot;Field Bus&quot; I/O directly connected to the Intellution computer if all that is done is monitoring. With drivers and/or communications cards added to the PC, you can do the monitoring without concern of using a PLC.

As for a brand of PLC, depending on your application, I found that almost all vendors will have a system that will do the job with little &quot;practical&quot; advantage over the other brand. I have been app engineer and general manager for distributors for Modicon and Siemens/TI, used extensive amounts of A-B, some Telemecanique, a good number of Automation Direct, and so on.

For PID I prefer the Siemens/TI and Automation Direct only because of the tuning interfaces. For small to midsize companies, I generally look to the Automation Direct first do to cost of product and software. Large companies usually have their own specs already, usually A-B or Siemens (whatever happened to GE in specs?). OEM's selling to North America, look to A-B. If you are selling outside North America, give your first and last look at Siemens.

Ah, the argument on why use a PLC! I have yet to find a hardware platform better suited for automation control than the PLC. Combine the low failure rate, lack of &quot;locking up&quot; and an interface that can be taught to most electricians to do basic changes and monitoring in a day, nothing comes close. You could do a micro-controller, code in assembler or 'C' and get the performance and reliability, but try teaching the electrician how to deal with it. You can put a PC with a RTOS in, even with similar interface to a PLC, but how will the hardware handle the environmental factors and for what price.

Oh, Well, maybe a little more than $0.02. Take Care

Dave Kaylor

http://www.ktech-usa.com

http://www.ktech-usa.com

 

[IEEMT]

I recommned Allen Bradley with RSLoxic software and wonderware, which is runing on an Windows 95 machine hook-up to the network to monitor whatever you need to do and control your I/O. On the other equiment I use different SLC 500 racks I use has a rack with 9 input slots with 2 output slots.

 

[grimmer]

cfordyce,

I have dealt with systems integrators who have used the
Koyo PLC's with success, and I'm still watching one particularly trying installation years later(replaced
an existing PLC) - so far so good!

They tell me support is just a phone call away, and they
are prompt and knowledgable.

The prices are a bit of a shock when you compare them
with just about everybody else, but the technology and
the quality appear to be there. Automation Direct also
offers(like everyone else)a total package, complete with
HMI interface, E-Net comm., etc., etc.

You really should check them out. They're available in
Ontario through Franklin Empire in Toronto, or directly
off the website. FE usually stocks most of the equipment
that you see on the site, and the prices, when converted,
are about the same.

No, I'm not connected with Automation Direct in any way,
and I'm from Ontario as well.

Good luck in your decision.

 

[kamenges]

Techshoot hit the nail on the head. It sounds like you have two separate issues here and you should probably should treat them as such.
'Back in the day' one of the easier ways to get I/O into a SCADA was through a PLC. In todays world of fieldbusses you may be better served switching over to one of the fieldbusses and reading the data as remote I/O.
As for the best PLC, that really is a pretty user specific preference. Just about everyone has an opinion on this (usually a strong one) but there is no right answer. It all depends on your needs.
Yes, AB and Siemens are kind of pricey. But do you think AB went to the money tree in the back yard and just picked off a couple hundred million to develop the ControlLogix platform? Development costs money. Also, in most cases you can't call your local AutomationDirect rep and have him come over to your plant to help you solve a problem. This is something I have done with both AB and Siemens free of charge. Well, not really free; its rolled into the price of the product.
That said, I have used AutomationDirect products and have been very happy with them. I have actually had fewer development issued with the Koyo stuff, probably due to the more straightforward devolopment environment. I'm at a point in my professional life where I don't prize what a distributor or rep can bring to the table as much as I once did. So the price savings that AutomationDirect brings in is pretty sweet.
OK, I really haven't said anything here. But by and large, you get what you pay for. With PLC's you will typically find you are paying for support and development options, not performance. With a gun to my head, considering all factors equally, I would probably go with Koyo. If performance and options were the only consideration, I would go AB ControlLogix.

Good Luck.
For what it's worth,
Keith