We have AB-SLC 500 PLC with Analog and Digital Input cards. The Electromagnetic flow meter has a Pulse output available. I would like to write the code for capturing this pulse output and capturing it to as a totalized flow.

 

What make/model electromagnetic flow meter are you using?

 

> What make/model electromagnetic flow meter are you using? <

It is an E&H flow transmitter. It is electromagnetic type flow meter.

 

Hi Fabian,

You need digital input, easy. You need the biggest width pulse you can from the meter. You need to use a one shot contact in plc. But what we need to know is how much data, what accuracy, what time frame,(one hour, one day, forever). This will have a dramatic impact on the code you need to write. All plc's have limitations to counts in one register, so you may need to some counting up, move, reset sort of stuff.

More details is always better,
Cheers Jaon.

 

The pulse output is a scaled (or scaleable) pulse...that is, each pulse directly represents n gallons/liters/other volume units.

All you need to do is to scale the pulse so that it is slow enough so that a digital input can receive it, without having to purchase a high speed counter card. Then all you have to do is to dedicate a register to the pulse, increment the register with each new pulse, and you have a totalizer.

Walt Boyes
Editor in Chief
Control and ControlGlobal.com
555 W. Pierce Rd Suite 301
Itasca, IL 60143

wboyes [at] putman.net
www.controlglobal.com

 

Thank you for the advice.

I am relatively new at writing PLC code. Could you please tell me how I would be able to scale the pulse input, on Allen Bradley PLC - SLC 500.

Sorry, I if I am bothering you too much.

 

The pulse scaling is done in the flow transmitter, not in the PLC. If you want to display in engineering units, you do that in the HMI.

Walt Boyes
Editor in Chief
Control and ControlGlobal.com
555 W. Pierce Rd Suite 301
Itasca, IL 60143

wboyes [at] putman.net
www.controlglobal.com

 

Fabian,

My company manufactures a meter gateway ("EtherMeter") that can count (totalize) pulses from a flow meter and make the total (and flow rate) available in DF1, EtherNet/IP, and Modbus protocols.

It will work with the E-H pulse output meter, as well as most "encoder-type" flow meters (eg Sensus, Neptune, Badger, Elster-AMCO/ABB/Kent, and many others).

We have many clients who use the EtherMeter with the SLC 500 series (and Micrologix, ControlLogix, and CompactLogix) because of its native DF1 and EtherNet/IP support.

Hope this helps! If I can provide more information, don't hesitate to contact me.