Near Intersection of I-35 & I-90 Southern Mn. | I believe the following to be correct but I've been wrong before.
With a Raven controller such as a 440 there is an internal pull up resistor in the controller. That's why the paper clip test works. There is also a pull up resistor in a Raven flow meter that is used for spray or fertilizer. When a Raven 440 is connected to a Raven flow meter, the pull up requirement is covered literally on both ends. If the Raven is connected to another type of flow meter which may not have a pull up there is still no problem as the Raven controller is handling the task.
If a non-Raven device such as an Ag Leader Application Rate module is used instead, it may not have a pull up resistor. If it is connected to a Raven flow meter (I do this on my planter) then there is still no problem as the flow meter itself provides the pull up.
The problem comes about when something like an Ag Leader Application Rate module is connected to another device that does not provide a pull up. In other words no pull up on either end.
Then a pull up needs to be provided which could be done in the harness connecting the two devices. I have had to do this a few times as a Tech. Since the Raven harness usually has a 5V constant power wire, a resistor can be placed between it and the signal wire to act as that "spring" that I referred to an earlier reply. The meter shorts the signal line temporarily to ground but once the meter releases the signal from ground, the pull up returns the value to 5V. This transition from HIGH to LOW back to HIGH is noted by the controller as a pulse which is counted and used to calculate the flow.
My personal use with my Ag Leader equipment involves Raven flow meters so I don't have issues of this type.
I'm currently working on a project for mixing batches of spray in my mixing shed. My plan is to use an Arduino with a large 4 digit display(s) connected to a 2" Raven flow meter The idea is the display(s) will show the batch total so I can stop a batch at a given amount. I typically decide how large a batch I wish to make and consult my chart for the amount and mixing order of each product. I start pumping in water and add the spray products to an inductor tank on the inlet side of my transfer pump. Once all the products have been "sucked in", I shut off the inductor and continue to fill with pure water. By watching the display I will know when enough water had been added. The batch is either being transferred to my planter, sprayer or tender trailer.
For testing I simulated the flow meter with a push button. I had to use the pull up concept for testing or pushing the button would sometimes causes several pulses to be created rather than just one. I am at the stage where I believe it is working so I have now attached a real Raven flow meter for my next stage of testing. The pull up is now handled by the Raven flow meter. I can turn the turbine in the loose flow meter with a pick and predictably create pulses one by one. This leads me to believe I have the wiring and program correct so far. I will have the Sketch or program in the Arduino divide the "count of pulses" by a conversion number so the value displayed represents gallons and tenths. My hope is that I will be able to display this value on the two fairly large displays making the batch total visible from about anywhere in my mixing area in the shed. The setup will remain in the shed as I do all mixing there. I keep all recipes, charts, spray products, water, measuring flasks etc. there. I have electricity in the shed to power my pumps, battery chargers and lights. The water is stored inside so I have a large supply of algae free water at ambient temperature. I'm fairly confident this will work and now need to devise some type of enclosure for the displays and Arduino.
Edited by tedbear 11/23/2020 07:24
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Raven 115-0171-750 harness diagram
