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DirectCommand™ Liquid Operation

by Jul 25, 2013DirectCommand™

As the growing year progresses, I hope the crops out there are looking well. Given this wet spring in most locations, there seems to be a lot of growth stage variability due to differing planting dates.  But by now, spraying should be well underway, hence this blog about common calls we receive with DirectCommand liquid systems.

Flow Meter cal number is unknown, or misapplication is occurring.

This can occur when the flow meter tag is missing or the flow meter cal number is inaccurate. Symptoms will be either over or under application – usually identified by filling the tank to a certain level, applying in a field and having left over product or coming up short.
Of course, the first consideration is to ensure the flow meter is not gummed up or plugged, especially with anhydrous.

Otherwise, this can be easily remedied by adjusting the cal number as follows:

Say the initial flow meter cal number was 78 pulses per gallon when misapplication was occurring. Apply starting with a known amount such as 250 gallons and after applying the whole amount, the display will read out what it thought was applied-say 275 gallons. The formula to adjust the cal number would be as follows:  275/250 x 78= a revised cal number of 86 pulses per gallon. So display total applied divided by actual applied multiplied by the original cal number.  Essentially, the flow meter cal number will increase if not enough product is being applied and decrease if too much is.

 

Boom sections are not turning on fast enough in point rows.

This can occur when a sprayer is entering areas where sections are incrementally turning on and product flow isn’t adequate for allowing the section to spray.

Minimum Flow will be the setting to change here; it works to maintain a low end operating pressure and accounts for that when boom sections turn off.  It also keeps a consistent spray pattern through the tips.

Increase the minimum flow value if sections aren’t turning on fast enough and lower minimum flow if pressure is spiking when sections are shutting off.

Calculate your Minimum Flow value by using this formula: The number of tips on the full boom x lowest recommended pressure for a tip based off a tip chart OR minimum GPM required to keep a desired droplet size = Minimum Flow.

Example: 54 nozzles x .24 GPM =13 GPM

Tip charts found here for Teejet and Hypro.


How do I control my Fence Row Nozzles?

DirectCommand supports up to 10 boom sections and up to 2 additional fence row nozzles.
Fence row nozzles can be set up two ways in switch mapping – as 1.) Boom sections or 2.)
Fence row nozzles. Either way can be done based on operator’s preference although setting it
up as boom sections assumes there are two free sections available for the fence row nozzles.

  1. Assigning fence rows as boom sections will map application when fence row nozzles are on and it will control flow rate accordingly. It is recommended to set the first and last boom section width for the fence row nozzles to actual spray width to correctly change flow control. Assign the fence row sections to the appropriate switch.
  2. Assigning fence row nozzles as fence rows in switch mapping, the system will not control the flow rate and will not map fence row application. Assign the left and right fence row nozzle functionality to any switch. The boom section next to the fence row nozzle must be on for the fence row nozzle to apply product.

When a switch is assigned the function of left or right fence row nozzle, a cable, PN 4002209-6, Fence Row Nozzle Cable is required for this operation.

 

Target rate is fluctuating or is too slow to acquire target rate.

If product application is not locking onto the target rate quickly, a short while with tuning the control valve should remedy the issue.
Before tuning, ensure the flow meter is operating normally and is not blocked.
Under controller settings, the value to tune will be dependent on control valve type.
For servo valves, the Response Threshold value will want to be increased to smooth the valve and help it lock onto target. Decreasing the value will allow the valve to acquire the target rate faster (more aggressive.)
For PWM valves, the Gain value will be decreased to smooth the valve and help it to lock onto target while increasing the value will allow the valve to acquire the target rate faster.

 

Boom Valve sections are not turning on

This will occur when a boom valve gets stuck, a cable has been damaged, an unseated connection, blown 30 amp fuse or a module failure.
To check where the issue lies, you’ll need a voltmeter and to put the display into “Rate Not Responding”
Requirements for Rate Not Responding are:

  • manual ground speed in the display
  • run screen loaded with active product
  • Master and boom section switches on
  • implement jumper in the Auxiliary port of the liquid product control module
  • AutoSwath off

First, unplug the connection to the boom valve and using the voltmeter, there should be 12 to 14 volts across points B and C and also across A and B. If you have voltage on pins A and B, you likely have an issue with the valve.
If you do not have voltage here, work forward to the module and check voltage at the Boom port of the liquid module. Use a common ground and check signal on pin 1 for boom section 1, pin2 for boom 2, etc. If you do have voltage here, you may have an issue with the boom valve cable.
If you do not have voltage at the boom port, check the high current connection into the LPCM at the 2 pin Deutsch connector into the module. If you have 12 to 14 volts here the issue may lie with the module.
If you do not have high power into the module, work forward to the battery and ensure a clean, tight terminal connection and check fuses off the battery cable.

 

Control valve will not open

This will occur when a control valve gets stuck, a cable has been damaged, an unseated connection, blown 30 amp fuse or a module failure.
To check where the issue lies, you’ll need a voltmeter and to put the display into “Rate Not Responding”
Requirements for Rate Not Responding are:

  • manual ground speed in the display
  • run screen loaded with active product
  • Master and boom section switches on
  • implement jumper in the Auxiliary port of the liquid product control module
  • turn AutoSwath off

First, unplug the cable to the control valve and should be 12 volts present here if Valve Response 1 setting is 100%. If you do have voltage here, there is likely an issue with the valve.

If you do not have voltage to the control valve, work forward to the LPCM and unplug the Channel 1 port to access pins 2 and 7. If you see a signal here, you likely have an issue with the control cable.

If you do not have voltage at the LPCM, unplug the high current connection into the module and check for 12 to 14 volts into the LPCM at the 2 pin Duetsch connector. If you have 12 to 14 volts here the issue may lie with the module.

If you do not have high power into the module, work forward to the battery and ensure a clean, tight terminal connection and check fuses off the battery cable.


For additional resources about DirectCommand liquid operation, great options are the Display Manuals and the Liquid section of the Knowledgebase. 

Of course a call to your local dealer or Tech Support is welcome, too!

Have a great summer!

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