Near Intersection of I-35 & I-90 Southern Mn. | I used to work as a Tech (L&D Ag Hartland, Mn) and have used Raven products and cables personally. Your system shows a variety of Raven connectors that were used throughout history.
Originally the Raven SCS-203 (manual 3 boom switch box) used the 6 pin trailer style disconnect at the hitch for a pull-type sprayer. Later when the SCS-400 came along, a cable for the flow meter was needed so a separate 3 wire CoAx cable was used. Later still, when the SCS-450 came about with 6 booms, more wires were needed. This is where the 16 pin AMP connector (like the one at the rear of the controller) was used at the disconnect point. It had enough pins to cover the booms, Inc/Dec and extra wires for Power and Ground. Later yet when the 660 came along more wires were needed and Raven went with the 37 pin connector for extensions and at the disconnect point. For your situation the 37 cabling would certainly work but contains many more wires than you need.
You mention the idea of making a cable to mate at the 16 pin connector in your picture. This is the approach I would pursue. As you mention it does not need all the wires that may be present. It would need Pins 3 & 4 for control and ON/OFF. It would need Pins 11, 12, & 13 for the flow meter. I don't believe the 2 pin Metri-pack connector is being used. It may be a carryover from a servo valve and ON/OFF valve that may have been used prior to the PWM valve.
As you are likely aware, a PWM valve controls the ON/OFF function as well as the rate function by controlling the oil flow to the orbit motor on the cart. A PWM control system does this by sending short "shots" of electricity followed by a short period of no electricity to open or partially open the PWM hydraulic valve.
This is done very rapidly such as 100 Hertz (cycles/second). Within each of those 1/100 of a second, the circuit could be completed none of the time, part of the time or all of the time. The ratio of the time the circuit is complete compared to the time slice is called the Duty Cycle. This means the Duty cycle could vary from 0% (never ON-valve closed) to 100% (always ON-Valve completely open) or somewhere in between.
The hydraulic valve is a plunger style valve with an armature that can open it. When no flow is needed, the controller produces a 0% Duty Cycle and the valve stays closed. When flow is needed since the calculated applied rate is lower than the target rate, the controller increases the Duty Cycle. Since this happens so fast, the plunger cannot go from fully closed to fully open and tends to "hover" at a position somewhere in between. When the calculated applied rate closely agrees with the target rate, the controller continues to send out pulses at that Duty Cycle. The controller constantly compares the calculated applied rate against the target rate and changes the Duty Cycle as necessary to attain close agreement with the target rate.
As the ground speed or target rate increases, there comes a point where the system limits are reached since the valve is being run at 100% Duty Cycle.
The beauty of using a PWM valve instead of a Servo valve is that the controller can remember the PWM Duty Cycle that was last used and jump back to it when application resumes. With a Servo valve, the response is often much slower and the system often needs to "hunt" up/down to get the applied rate to agree with the target rate. This can result in unwanted oscillation.
Here's what I would do concerning the polarity of the PWM wires. Pins 3 & 4 at the 16 pin junction will eventually get to the PWM connector at the PWM valve on your maze of wires. Use a meter to determine whether Pin 3 goes to the left pin or the right pin of the PWM plug. Check that Pin 4 goes to the other pin at the PWM plug. Construct the new replacement cable accordingly. If the system worked before, it should work with the new cable.
The polarity of the Pins 3 & 4 may not matter since many PWM valves do not involve chassis ground so either polarity would be fine. However, I would still perform the continuity test suggested above. |
Need some help with Raven cabling.
