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Ag leader liquid control module rate not working
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Posted 11/20/2023 07:34 (#10489124 - in reply to #10489075)
Subject: RE: Ag leader liquid control module rate not working

Near Intersection of I-35 & I-90 Southern Mn.
SDfarmer44 - 11/20/2023 07:04

Good to know, I was thinking if in manual you would be kind of bypassing the pwm, yes the control valve is set to pwm still. The sprayer was just in the shop for a PIP to remove and replace the front axles. I had to do calibration to the steering to make that work, there wouldnt be something related to the wheels coming off that would change the rate control would it? the gps speed still reads accurate.

With a PWM setting and working in manual, a PWM signal is still sent out to the control valve. Pulse Width Modulation (PWM) works on the idea that the speed of a motor of the opening of a hydraulic valve can be controlled by perodic "shots" of electricity. Sometimes the "hot" is switched ON/OFF rapidly or the "ground" is switched ON/OFF rapidly. Either way the result is the same.

This is done very rapidly. Quite often this is 100 Hz or 100 cycles per second. That means for each 1/100 of a second, the circuit could be complete for none of the time, part of the time or all the time. This is called the duty cycle and can range from 0 - 100%. If the duty cycle is zero, then the motor would not turn or a hydraulic valve would be closed. If the duty cycle is 100% which is equivalent to a constant 12V, then the motor would run full speed or a hydraulic valve would be fully open. In normal operation the duty cycle is somewhere in between and the motor would be running less than full speed or a hydraulic valve would be partially open.

With your sprayer operating properly in automatic, the system will compare the applied rate that it believes it is applying to the target rate that you have entered. If the applied rate is not in good agreement with the target rate, the system will make an attempt to increase or decrease the rate as necessary.

With a PWM setup, the system will change the duty cycle which in turn changes the hydraulic flow and ultimately the pump output.

This means in manual, the system will put out a constant duty cycle to hold the hydraulic valve partially open. You can change the duty cycle yourself by using the INC or DEC arrows on the display. In auto Rate 1 or Rate 2, the system will change the duty cycle for you based on the comparison between applied rate and target rate.

I still feel that there is some confusion in the PWM settings which is what the Ag Leader Techs were suggesting. Doing a recalibration of the steering should not have caused the spray control problems that you are experiencing.

An old trick that I've used when having difficulties such as this is to create a new configuration from scratch. There have been numerous times as a Tech where I was certain that I had everything set properly. Out of desperation, I would create a brand new configuration from scratch and it would work fine. By new configuration, I mean everything. Start over as if this is a first time installation, create a new vehicle etc. and use revised names so you can keep the "old" and "new" straight in your own mind.

Good luck

Edited by tedbear 11/20/2023 07:37
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