Near Intersection of I-35 & I-90 Southern Mn. | C D Farm - 3/29/2014 05:39
I am trying to connect a Raven RFM200P to a PLC to read the pulses. anybody ever do this before?
I understand that the red wire is signal, the black is 12V DC power and the shield is ground. Is that correct?
Would I need to use a resistor to make it work? Is it not giving me clean enough pulses?
Or does anybody know of a better flow meter for 3" that has a good range of gpm?
this Raven does not have a very good range at the top end.
Does the flowmeter still have the Raven Conxall connector on it? If you have cut it off do you still have the connector? If so the wire going to the pin at the 6 O'clock position is the signal wire. The other pins at 2 and 10 O'clock will be power in and ground. These positions will be dependent on which connector you are looking at but the 6 O'clock is certainly the signal wire.
Concerning the need for a resistor - maybe yes. As the turbine turns a magnet passes by the sensor causing the signal line to be pulled to ground. When the next magnet of opposite polarity passes by the sensor, the signal is unlocked and returns to the high logic state. In a complete Raven system the display has a pull up resistor in it but the flowmeter does as well. In certain situations I have used a 10K ohm resistor connected to the supply voltage (generally 5 V although the new flowmeters can tolerate 12V) to act as a pull-up for the signal line. The flowmeter circuitry is able to sink this current to ground when necessary.
This pull-up resistor may be necessary as the signal line may not be returning to the high state cleanly enough to trigger the PLC solidly.
I assume this is for some type of stationary situation (feed, fertilizer etc.). The product involved may be important. A local feed mill used an old Raven flowmeter for measuring fat going into the feed. I guess it worked reasonably well but did require some maintenance.
Edited by tedbear 3/30/2014 08:30
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Raven RFM200P Flow meter
