adccommunitymod (AutomationDirect) asked a question.
Created Date: April 13,2008
Created By: Ibsft
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Hey guys, I'm looking for advise on liquid level sensing. It looks like the most flexible way would be a continuous level sensor with a 4-20 ma output connected to a analog input card in the plc. The PLC is a 305 with the DL350 cpu. I need four level setpoints and have modified a program to work with them. Problem is, though have done some programming over the years, I am not a programmer. I have never worked with registers and accumulators, etc, just plain old ladder logic and it appears a bit confusing at first glance. We have asked around to find a programmer in our area versed in DirectLogic PLC's and came up empty. That leaves the options of buying a level sensor that comes complete with at least four adjustable setpoints or learning how to program for the analog card. As always, time for the project is very short, so I guess the first question is can an average guy learn how to program for the analog card and setpoints in a couple of days? What other programming support options are there? Where or how should one go about finding Direct Logic programmers? Thanks for looking.
Created Date: April 13,2008
Created by: Steve Bailey
Where or how should one go about finding Direct Logic programmers?
Posting the question as you did is as good a way to start as any. Where are you located? Do you need to be working with someone local to you or are you willing to merge the code that someone writes for you with your existing program?
The learning curve to pick up the techniques you need to handle analog isn't too hard. The thing you most need to keep straight is that the native data type in the 305 is BCD and that you are limited to integers.
Created Date: April 13,2008
Created by: Ibsft
The equipment is near Adrian, MI (southeast Michigan). Yes, I would be willing to merge the code. Trouble shooting any startup problems specific to the analog card/sensor arrangement during startup may be a concern though.
Created Date: April 13,2008
Created by: Steve Bailey
From your description, the application doesn't sound too difficult. If you post the catalog number of the analog module you plan to use and the slot where it will be located, I think the members here will be able to point you in the right direction.
Created Date: April 24,2008
Created by: Ibsft
Well here goes. It’s a D3-350 CPU in an 8 slot rack. Slot 4 has the F3-08AD-1 analog input card connected to a 4-20mA level sensor.
I am using just the first channel on the analog card. Here is the way the ladder logic for the card displays in the Mnemonic view:
462 STR SP1
463 LD K 0100
464 OUT V7664
465 LDA O4000
466 OUT V7674
Here is the logic for 4 different level settings turning on control relays which are used elsewhere in the program:
467 STR V4000 K299
469 OUT C400
470 STR V4000 K1664
472 OUT C401
473 STR V4000 K2560
475 OUT C402
476 STR V4000 K3285
478 OUT C403
Works? Not even close?
Created Date: April 24,2008
Created by: KPrice
lbsft,
You asked about System Integrators versed in DirectLogic PLC’s. Have you looked at the SIDirect System Integrator list on the AutomationDirect website? I see there are companies listed in WI, OH, IN, and IL, as well as other states farther away from MI. We are a listed integrator in PA, near Philadelphia. I very much agree with your concern to want a person on-site during startup. I hope you find a SIDirect company near you to help out. This forum is great for specific programming help, but you may need more comprehensive support.
Created Date: May 08,2008
Created by: Ibsft
Kprice, thanks for the info. An advance search nets only a few Integrators (of which you were one) to do what we want. It’s a shame since programmers for AB, Mitsubishi, Siemens, etc are a dime a dozen around here.
Anyhow the level control seems to work well, though we have experienced a strange hardware issue.
Created Date: May 08,2008
Created by: KPrice
Ibsft, glad to hear that you have the level control working well, but what is the strange hardware issue?
Created Date: April 13,2008
Created by: Ibsft
Hey guys, I’m looking for advise on liquid level sensing. It looks like the most flexible way would be a continuous level sensor with a 4-20 ma output connected to a analog input card in the plc. The PLC is a 305 with the DL350 cpu.
I need four level setpoints and have modified a program to work with them. Problem is, though have done some programming over the years, I am not a programmer. I have never worked with registers and accumulators, etc, just plain old ladder logic and it appears a bit confusing at first glance.
We have asked around to find a programmer in our area versed in DirectLogic PLC’s and came up empty. That leaves the options of buying a level sensor that comes complete with at least four adjustable setpoints or learning how to program for the analog card. As always, time for the project is very short, so I guess the first question is can an average guy learn how to program for the analog card and setpoints in a couple of days?
What other programming support options are there?
Where or how should one go about finding Direct Logic programmers?
Thanks for looking.