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FLOW MEASUREMENT USING PLC
measure the flow rate and volume of the flow using a positive displacement flowmeter and plc
By MOHAMED RAFIH on 9 April, 2011 - 5:21 am

Dear Friends,
I have been given a project in plc. the project is to measure the flow rate and volume of the flow using a positive displacement flowmeter and plc. i am having a VIPA plc and the output from the PD flowmeter is pulse output. i am not sure how to do this project. i am having a doubt whether to use simple digital input card or have to go for any special cards.

and also if some one can help me with the whole idea please help me, it will be a great help.

thank you
mohamed rafih
psrafi@yahoo.co.in

By Steve Myres on 9 April, 2011 - 11:38 am

Depends on the pulse rate. You may need anywhere from a normal digital input, to a fast digital input, to a counting module. Look at the maximum flow rate you anticipate and the pulse rate of the instrument in pulses per unit volume.

Refer to Steve's reply quoted below, May I ask to explain more about the effect of the pulse rate? Or the pulse rate of the instrument in pulses per unit volume.

Thank you,

"Depends on the pulse rate. You may need anywhere from a normal digital input, to a fast digital input, to a counting module. Look at the maximum flow rate you anticipate and the pulse rate of the instrument in pulses per unit volume."

Since Vika PLC's support Modbus, you can interface your PLC to an EtherMeter (manufactured by my company, SCADAmetrics) via Modbus. The EtherMeter is capable of calculating and transmitting totalization and flow rate from one or two connected flow meters.

If you are using a North American, AWWA-type positive displacement flow meter (eg Sensus, Neptune, Badger, Master Meter, Elster AMCO, Hersey, etc), you can utilize an encoder-type meter signal for error-free totalization of both positive and negative flows.

Otherwise, the EtherMeter can handle pulse output meters from most manufacturers. The pulse needs to be a dry contact type (eg reed-relay or open-collector).

Hope this helps!

Jim