Allen Bradley 1769-L32E I/0 valve control

Ones_Zeros · Oct 3, 2015

Hello,
I'm still learning PLC's and I have the task of controlling 2 actuating valves.
Theses valves need to move at the same time.
So when I type my HMI Wonderware program for the valve to move 10% open, both valves will move 10% open.
Here is what I have:

Valve_1, Connected to Analog Output 1
Valve_2, Connected to Analog Output 2

My question is, how would I configure these valves to move at the same time?
Would I do this in RSLogix 5000 program or configured in Wonderware?, have to add that these valves will be manipulated manually from a remote site they won't be configured in an PID loop.

Could you help explain to me how to do this please?

Thanks,

PapaSmiff · Oct 3, 2015

Are the current requirements of the valve low enough so you can run them both off of one output?

Ones_Zeros · Oct 3, 2015

I had thought about putting them on 1 output and it may be ok, but they wanted to put them on seperate outputs.

Ones_Zeros · Oct 3, 2015

any thoughts on the best way to do this with the control valves connected on seperate outputs?

Thanks for the help

PapaSmiff · Oct 3, 2015

OK. You could have your calculated value for the valve position assigned to two tags at once (by using two MOV instructions in one rung). Those two tags would be correlated to the two separate analog outputs.

Unfortunately, that may be too simple. What are the valves controlling? If, for example, you are trying to get two cylinders to move at the same rate, you could bind up a machine simply because one valve lets marginally more fluid (air, oil, water, etc.) through it than the other. The cylinder it controls would then move slightly faster, causing the bind.

Unless a manufacturer matches them, no two valves will act exactly the same. Close, but not identical. It depends on your application as to whether or not it matters.

Ones_Zeros · Oct 3, 2015

Hello,
both of these control valves will be controlling natural gas.
the valves were put in to were they both need to be manipulated at the same time.

both valves are the same with the same actuators.

Not sure how to do this.
could you explain how to do this in the PLC please?

Thanks

Mickey · Oct 3, 2015

Two move instructions in parallel on the same rung.

Are both valves always going to operate at the same time at the same %?

Is there only one input from the SCADA system?

Ken Roach · Oct 3, 2015

both of these control valves will be controlling natural gas.

I almost never discourage people from taking on challenging applications as learning experiences.

But burner and boiler and furnace and flame control require specific instruments, control methods, and safety methods. Those kinds of control tasks are governed by specific industry standards that effectively have the force of law, because the risk of serious or catastrophic injury or damage is high.

You should take a step back and investigate which regulatory standards cover your application and assess your familiarity with them to decide whether or not you want to continue with this project.

PapaSmiff · Oct 3, 2015

I don't think I did the quote right but Ken is right on the money:

But burner and boiler and furnace and flame control require specific instruments, control methods, and safety methods. Those kinds of control tasks are governed by specific industry standards that effectively have the force of law, because the risk of serious or catastrophic injury or damage is high.

I personally lack that expertise; I should not be advising you.

Mickey · Oct 3, 2015

Where did the OP say its burner/boiler/furnace control?

Good advice if it is.

Ones_Zeros · Oct 3, 2015

Hello Mickey,

Two move instructions in parallel on the same rung.

Are both valves always going to operate at the same time at the same %?

Is there only one input from the SCADA system?

1. never had much dealings with the MOV function, is that all there is to it? just put 2 MOV functions in parallel

2. yeah, as of now they want both valves to operate at same time at the same %

3. Yeah, what they want is have one input on the SCADA program to operate both valves.

thanks again

Mickey · Oct 3, 2015

1. never had much dealings with the MOV function, is that all there is to it? just put 2 MOV functions in parallel

Yes, they are called instructions in the AB world.

I don't have RSLogix5000 or I would give you an example.

Maybe those that do can provide one for you. It would help if you can post your program and tell the forum which outputs you are using. Zip the program first.

Ken Roach · Oct 3, 2015

Because these valves are controlling natural gas, I figure this is a combustion process of some kind. Some of his posts from last year also deal with oxygen detection and purge blowers.

To answer the basic programming questions:

Yes, you can use two MOV instructions to put the setpoint onto two physical output channels. MOV can be in parallel or in series in a Logix 5000 rung.

Mickey · Oct 3, 2015

Ken, I worked for a natural gas utility for 34 years. Storage and pipeline department.

They did have boilers and cabin heaters, etc. all controlled by a burner mangement system, as they should be.

But there are 100's of other valves controlling flow,pressure, direction ( move the gas to these pipes instead of those). I do understand that ultimately at the end of the pipe it is going to get burned. After all that is what the stuff is for.

Allen Bradley 1769-L32E I/0 valve control

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