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Old March 12th, 2018, 02:57 PM   #1
EricBig
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Air valve

I have this proportion air?
using 4-20MA command
I am using compact logix i have both analog input and DC Input cards?
do I also control the power through the PLC? to turn on and off?

Which card i am supposed to control the air valve? (analog or dc)?
cards # IQ16 & IF4
description below.
https://www.proportionair.com/litera...stallation.pdf
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Old March 12th, 2018, 03:12 PM   #2
padees
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You will need an analog output card to control the regulator. Just power it up with DC, don't have to go thru the PLC for power supply. You could tho.

To turn it off, give it whatever you consider a zero signal.

We did one project with Bellofram analog regulators. They worked OK and we had to get the true off option (so it doesn't leak air) Since then, I have been using SMC EtherNet/IP regulators. Those are nice.
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Old March 12th, 2018, 03:19 PM   #3
EricBig
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Quote:
Originally Posted by padees View Post
You will need an analog output card to control the regulator. Just power it up with DC, don't have to go thru the PLC for power supply. You could tho.

To turn it off, give it whatever you consider a zero signal.

We did one project with Bellofram analog regulators. They worked OK and we had to get the true off option (so it doesn't leak air) Since then, I have been using SMC EtherNet/IP regulators. Those are nice.
But if u look at page 3 in the specs. At the right side it tells me a DC common & command
Are u sure to use analog out?
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Old March 12th, 2018, 03:31 PM   #4
Mickey
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Please provide the complete model number for your valve.
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Old March 12th, 2018, 03:32 PM   #5
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Quote:
Originally Posted by EricBig View Post
But if u look at page 3 in the specs. At the right side it tells me a DC common & command
Are u sure to use analog out?

Do you have a 3-pin or 5-pin model?

Looks like the 5-pin model adds the option for analog feedback which would be an analog input to the PLC. This is in addition to the power and the 4-20mA PLC output you will need to power and command the valve.
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Old March 13th, 2018, 12:36 PM   #6
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Quote:
Originally Posted by OkiePC View Post
Do you have a 3-pin or 5-pin model?

Looks like the 5-pin model adds the option for analog feedback which would be an analog input to the PLC. This is in addition to the power and the 4-20mA PLC output you will need to power and command the valve.
OkiePC: Yes so, i connected my air valve to my analog output card#1769-OF4/A its a compact logix.
and created 5 tags
1- MAX_PSI ->100
2- MIN_PSI -> 0
3- MAX_Engineering_Unit -> 20,000
4- MIN_Engineering_Unit -> 4000
5- Data_Input_PSI -> my controlling input

now could you please confirm if my formula is right or what i am missing please?

=> [100/(20,000 - 4000)] = 0.00625
=> 0.00625 x Data_Input_PSI = output in PSI to control my air valve.

Is that correct?
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Old March 13th, 2018, 12:58 PM   #7
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Quote:
Originally Posted by EricBig View Post
OkiePC: Yes so, i connected my air valve to my analog output card#1769-OF4/A its a compact logix.
and created 5 tags
1- MAX_PSI ->100
2- MIN_PSI -> 0
3- MAX_Engineering_Unit -> 20,000
4- MIN_Engineering_Unit -> 4000
5- Data_Input_PSI -> my controlling input

now could you please confirm if my formula is right or what i am missing please?

=> [100/(20,000 - 4000)] = 0.00625
=> 0.00625 x Data_Input_PSI = output in PSI to control my air valve.

Is that correct?
I'm lost on that last part. If you want 100 psi, you will need the output data to be 20000. But if you set up the card to do the scaling for you, you just need to populate Data_Input_PSI with a value of 100.

If you are rolling your own scaling formula (which I think is the case)

You will want to compute the raw data as Data_Input_PSI/MAX_PSI*(MAX_Engineering_Unit-MIN_Engineering_Unit)+MIN_Engineering_Unit

This assumes MIN_PSI will always be zero. Also, I disagree with your naming of the MIN and MAX Engineering units, that should be called MIN_RawData and MAX_RawData or something...It isn't really engineering units.

I may have misunderstood what you're doing, so let me know if that is the case.
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Old March 13th, 2018, 01:17 PM   #8
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Quote:
Originally Posted by OkiePC View Post
I'm lost on that last part. If you want 100 psi, you will need the output data to be 20000. But if you set up the card to do the scaling for you, you just need to populate Data_Input_PSI with a value of 100.

If you are rolling your own scaling formula (which I think is the case)

You will want to compute the raw data as Data_Input_PSI/MAX_PSI*(MAX_Engineering_Unit-MIN_Engineering_Unit)+MIN_Engineering_Unit

This assumes MIN_PSI will always be zero. Also, I disagree with your naming of the MIN and MAX Engineering units, that should be called MIN_RawData and MAX_RawData or something...It isn't really engineering units.

I may have misunderstood what you're doing, so let me know if that is the case.

Yes i believe you are totally right for the name tags.
and Yes i need to run my own formula to control the PSI
that been said with your formula as follow.

Data_Input_PSI/MAX_PSI*(MAX_Engineering_Unit-MIN_Engineering_Unit)+MIN_Engineering_Unit

which will equal to:[[X(input) / 100] * [20,000 - 4000) + 4000]

Is that what you mean?
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Old March 13th, 2018, 01:26 PM   #9
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Quote:
Originally Posted by EricBig View Post
Yes i believe you are totally right for the name tags.
and Yes i need to run my own formula to control the PSI
that been said with your formula as follow.

Data_Input_PSI/MAX_PSI*(MAX_Engineering_Unit-MIN_Engineering_Unit)+MIN_Engineering_Unit

which will equal to:[[X(input) / 100] * [20,000 - 4000) + 4000]

Is that what you mean?
Yes, so plug in some numbers to check:

If you want 50psi, you will have:
(50/100)*(16000)+4000 = 12000 (12 milliamps)
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Old March 13th, 2018, 01:33 PM   #10
EricBig
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Quote:
Originally Posted by OkiePC View Post
Yes, so plug in some numbers to check:

If you want 50psi, you will have:
(50/100)*(16000)+4000 = 12000 (12 milliamps)

I really appreciate your help.

Thank you so much
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