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Learn how CANBus is a control system method, its benefits over PWM, setup instructions, and termination requirements for efficient hardware installation in Jaguars using RJ12 cables.
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CANBus CANBus is a control system method that can be used instead of the conventional PWM system. It uses RJ12 cable, which is similar to ethernet cable, to link Jaguars together.
Advantages • Ethernet cables are more robust than PWM’s • Less wire is required because the cable runs from one Jaguar to the next • Jaguars can handle PID loops, freeing processing on the CRio
More Advantages • Jaguars in CAN can have Potentiometers or Encoders wired directly to them. • CAN Jaguars can control motors just like normal jaguars, but they can also control them according to position, voltage, speed, or RPM.
Disadvantages • If one cable fails, the rest of the chain fails • Only 20 ft. of cable may be used • Only one Pot. or Encoder may be used per Jaguar • Only 16 Jaguars (max.) may be used.
Things You’ll Need • RJ-12 Cable, Connectors, and Crimper • At least one Black Jaguar • Two 100 ohm resistors • Modular Adapter: RJ-12 to DB9 Female (Digikey Stock No. 046-0003-ND)
Making the Adapter • The DB9 to RJ-12 adapter will need to be assembled once the pieces are purchased. The following table tells which pins from the DB9 end go to which wires on the RJ-12 end.
Placing the Adapter • The adapter should go on the end of the CRio, by the Ethernet ports.
Termination Because CANbus is a bus system, it needs termination on either end of the network with a resistor. This means that on the cable connecting the adapter and the black Jaguar (or even inside the adapter), the Red and Green wires (wires 3 and 4) need to be bridged with one of the 100 ohm resistors. The second resistor will be used later.
Crimping the RJ-12 Cable To make an RJ-12 Cable, take one end of the cable and strip about ¼ inch of the external casing. DO NOT strip the individual wires. Insert the wires according to the diagram below (1 is white) and crimp.
The Other End • When making RJ-12 cables, each end is crimped with the wires in the same order. This means that if you look at the cable, the ends will look upside-down from each other.
Connecting the Jaguars Each Jaguar will connect to the next in the network, as shown below. The power cables hook up as normal.
Termination • In the last Jaguar, there needs to be a terminator plug where the next cable would be. The terminator plug is simply an RJ-12 or RJ-11 connector with the ends of a 100 ohm resistor crimped into the center 2 pins.
