Near Intersection of I-35 & I-90 Southern Mn. | With many Ag CAN systems there is usually a terminator on the "far" end by the most distant device. The purpose of the terminator is to help with interference issues. Having a single terminator on the chain of devices is adequate, having too many may actually be counterproductive.
The spur as you called it would likely be to add another device. Since you likely already have a terminator which can remain where it is or moved further down the line. You would not need to get another terminator.
The resulting CAN wiring network means all devices have access to power and ground to power the logic in each device. They each have a CAN High and a CAN low wire that convey the information around the systems. By using both a CAN High and a CAN Low wire interference from 2-way radios, alternators etc is reduced. Those modules that need to open a valve or do some other "work" will often have a High current 12V and Ground source to handle those tasks.
With most CAN systems, each CAN device has a unique address and serial number. Each packet of information begins with an address. That way a device can determine if the information is for them or another device. In some respects this is like the old telephone Party Line. Each person can hear the conversation and butt in but they are NOT supposed to.
With an Ag Leader system you can create a configuration that uses several modules on the bench. The modules do not need to be connected when the configuration is created. The first time you attempt to use the configuration, the system looks to see if there is exactly one module of each type specified in the configuration. If the system finds some extra modules, that is no problem since they will just not be used. If there are "extra" modules of the same type (two liquid modules for example) the system will force you to choose which one is doing what.
The system then notes the module serial numbers and assumes you will be using the same modules next time as you did the last time. This is usually the case and the system proceeds. If it cannot find the serial numbers it was expecting, it asks some questions such as if you have swapped out a module or another alternative. If it cannot find a module of the proper type it will refuse to proceed and you must investigate as the system needs the module to perform the expected task.
This pertains to me since I use a Liquid Product Control Module on the planter and a different one on the Hagie sprayer. The configuration for planting is expecting the serial number of the Liquid Module on the Planter and the configuration for spraying with the Hagie is expecting the one on the sprayer.
Should the module on the planter fail, I could swap in the module from the Hagie. The system would notice that the serial number is not the same as it was expecting but found one of the proper type and ask me if I had changes modules. I would answer yes and that serial number would then be expected for subsequent uses. If I moved that module back to the Hagie there would be no problem there since the serial number would match what was used previously with the Hagie.
Edited by tedbear 5/22/2026 16:43
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CAN BUS wiring question
