Need help to choose an Allen Bradley system

[Mickey]

TWControls provided this at MRPLC, excellent review

http://forums.mrplc.com/index.php?showtopic=6765

 

[mgvol]

Even if you went with the ML1200, and the IF2OF2 modules, you have a fairly old version of RSLogix 500 (V 5.5). It probably doesn't have the wizard for easy configuration of the module for Scaled-for-PID and you would have to do it the old fashioned way: hard-code the configuration bits and copy them to the module configuration words on first-scan. You would probably want to update your software anyway, to take advantage of the configuration wizards. Since the ML1100 offers online editing and will be cheaper, I would go with it.

 

[TimWilborne]

Don't use the embedded analog inputs of the ML1100. You already need 3 outputs so you will have 4 inputs. The embedded inputs can't be scaled for PID which makes it a pain.

I don't think much of the Web Server but it may serve your purpose. I'll play with the password protection and let you know about it

 

[TimWilborne]

The only mention of passord protection is the manual the Dash referenced. I don't see a way to use it but there probably is. Don't think you will need it though. There is a new LCD function that lets you control what is displayed. If the parameter is not in there then the operator can't change it.

If they want password protection, call Rockwell or your local rep and make sure how it works. I will look at it a little more tommorrow. Another idea would to be to setup a second LCD page for the operator to enter a passord that would have to match a value in the controller before it would switch to the LCD page that you can change the value on. The password would not be masked so an operator looking over the shoulder could see it.

Remember though, passwords would be a pain to enter since it does not have a keypad. Just the arrow keys

 

[Cryogen]

Yes I need to check on how the display works. Last time I spoke to an AB rep about this, their comment was its hard to use it to enter data.

But this application would not involve continuous monitoring or operation. They will have to tweak the setpoint once in a while. But password is very important..

TWcontrols, your logic using two LCD pages sounds good. But there must be an ablility to logoff also.. probably reset what they entered or something.. Either automatically or manually..

Thanks for all your help

 

[Cryogen]

Also, is there a difference between using
one 1762-IF4, one 1762-OF4 compared to using
two 1762-IF2OF2?

My analog input(1) and outputs(3) are 4-20mA..

 

[Ken Moore]

Setpoint entry

You may want to consider a lowend text only HMI for the setpoint changes.
It could be mounted on the door, and the enclosure wouldn't have to be open.

One choice might be: http://www.ezautomation.net/products/eztext_models.php

I'm sure there are others also.

 

[TimWilborne]

Also, is there a difference between using
one 1762-IF4, one 1762-OF4 compared to using
two 1762-IF2OF2?

My analog input(1) and outputs(3) are 4-20mA..

No difference, but you need the analog input so might as well use two 1763-IF2OF2s.

Also just remembered, not only can the built in ML1100 analog not be scaled for PID, but is also 0 to 10 VDC only

 

[TimWilborne]

Take Ken Moores advice or do it over the ethernet port if possible, I really don't really like to open panels to make regular adjustments.

Plus I just got back from an Arc Flash Seminar. Is it legal to even make adjustments from the LCD without Arc Flash Protection. From what I understand this is something OSHA is really pushing now. Don't know how strict you company is.

 

[Mickey]

TWControls said:

Also just remembered, not only can the built in ML1100 analog not be scaled for PID

Why not?

 

[TimWilborne]

Let me clarify, yes you can scale it in ladder, but it does not have the option to be "Scaled for PID" under "Data Format" of the I/O Configuration as the expansion analog can be

 

[Mickey]

Thanks, I thought I was missing something in the manual.