Need help to choose an Allen Bradley system

Cryogen · Feb 16, 2006

Our customer is requesting an Allen Bradley system (preferably a PLC) for one analog 4-20mA input and three analog 4-20mA output. There will be one PID(level control) on the system.

Can you guys give any recommendations? I know its AB, but there should be a cheaper solution considering there is nothing complicated here..

I appreciate any help!!

CroCop · Feb 16, 2006

The ML1500 isn't overly expensive for AB.

Ken Moore · Feb 16, 2006

Take a look at the ML1200: http://www.ab.com/plclogic/micrologix/1200/

Or perhaps the 1100: http://www.ab.com/plclogic/micrologix/1100/

Both use the same analog expansion modules: http://www.ab.com/en/epub/catalogs/12762/2181376/2416247/25463/2164029/tab5.html

I have no experience with the ML1100, but have used the 1200 without any issues.

TConnolly · Feb 16, 2006

You can get into a ML1200 with the Analog IO for around $500.00

A CompactLogix with the IO will run just over a grand. The ML1200 PID is a good PID, but the compactlogix has a much more advanced PID instruction available.

Andybr · Feb 17, 2006

Whilst I do not agree with Alaric that the ML1200 PID instruction is good it does work and it is (relatively) cheap. The problem is that scaling the 4-20mA for the PID loop is ridiculously complicated. You should make sure that you read the help files and all of the available tech notes before you code your loop(s).

TimWilborne · Feb 17, 2006

Actually since he need 3 analog outputs use 2 1762-IF2OF2s. These can be scaled for PID in the I/O Configuration

Cryogen · Feb 17, 2006

Thanks for all your help. I think I will go with Micrologix 1200 and use two 1762-IF2OF2s modules. The current version of RSlogix I have is 5.50. Is this fine for me to use?

Can I consider ML1000 Analog? Is there a good price difference between ML1000 and ML1200?

I have never programmed PID in Allen Bradley. For someone to start, how much time will it take to program one PID loop?

Thanks again for your help!!

Tom Jenkins · Feb 17, 2006

I avoid the ML-1000 for any analog work. Math functions and scaling are limited, and you only have one comm port. I'm not sure if it as PID. For what you are doing, the 1200 is a more economical choice long term.

Cryogen · Feb 17, 2006

ML1200 should be a good balance of price and functionality..

Now, the customer wants the ability to change the setpoint and PID. This application will not have an operator interface, they would have to connect a laptop to the PLC.

I want to let them change the setpoints, PID etc but i do not want them to add more code.. or be able to download new program. Is this possible for me to do? Can I password protect say a subroutine or something?

dash · Feb 17, 2006

If the 1100 has enough I/O it may be a better choice. It has an LCD display that you can give them the ability to change setpoints with. Also, it allows online programming, which the 1200 does not.

Darren

Cryogen · Feb 17, 2006

If I go with ML1100, I may have to update my RSlogix500 right?
I assume the display can be password protected?

dash · Feb 17, 2006

Yes you will have to update RSLogix 500, but I am not sure about the passwords.

dash · Feb 17, 2006

See this.
http://literature.rockwellautomation.com/idc/groups/literature/documents/wp/1763-wp001_-en-e.pdf

It states you can password protect each operator input separately (I would verify though, that sounds like a lot to me, since it allows 48 integers).

Also, neat feature I was unaware of is that you can also use webpage for remote changes to setpoints.

See this for webpage manual.

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1763-um002_-en-p.pdf

Darren

Cryogen · Feb 17, 2006

Neat.. I just noticed it has two embedded analog inputs too..

curlyandshemp · Feb 17, 2006

Go with the M1100.

This allows online changes to the logic, whereas the rest of the Micrologix family does not. Nothing more frustrating than waiting till production is over at 2:00am to download logic changes or updates to an application.

Ian

Need help to choose an Allen Bradley system

Cryogen

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CroCop

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Ken Moore

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TConnolly

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Andybr

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TimWilborne

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Cryogen

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Tom Jenkins

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Cryogen

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dash

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dash

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