CAN Testing Homepage

What is PWM: Within the FRC controls system, the most common way to transmit an electrical signal is through PWM (pulse with modulation) cables going from the digital sidecar to the Jaguar, Victor, Spike Relay, etc. Each component has its own unique PWM cable and within the code is referenced through that number.

What is CAN: A slightly more advanced and more complicated controls system involves CAN (controller area network), which will communicate the signal through ethernet cables. Coming from the RS-232 port of the cRIO, special CAN cables connect it to the first Jaguar. That Jaguar is connected to the next and so on until they are all daisy-chained together. The last Jaguar in the list holds the terminator plug, ending the chain. Each Jaguar is assigned a unique ID (#1-infinity) and can be referred to by this number. The CAN wiring method is particularly attractive because it offers a neater solution to the often messy jumble of PWM cables. However, since all the Jaguars are connected, if one fails then several more could go down as well. Within LabVIEW there are many CAN speciality VIs that allow for advanced closed loop control (see documentation for more details).

What is 2CAN: An offshoot of CAN is 2CAN, which allows for even more advanced control. Here in to the equation is added a 2CAN box (can be found at http://www.crosstheroadelectronics.com/2CAN.htm ). Here an ethernet cable connects the cRIO to the 2CAN box. Then the CAN cables goes from the 2CAN box to the Jaguar and daisy chains from there.

CAN Cables Some people choose to build their own CAN cables because the materials and tutorials are available. However, we at 1912 prefer to buy them at a fairly cheap rate ( http://www.crosstheroadelectronics.com/Cable.html ) because it is not only easier but guarantees a good cable connection.

CAN Documentation https://decibel.ni.com/content/servlet/JiveServlet/download/14865-3-26505/CAN%20Getting%20Started.pdf

2CAN Documentation http://www.crosstheroadelectronics.com/2CAN%20User%20Manual_v_1_5.pdf

Combustion's Use of CAN and 2CAN: Throughout the 2011 summer and 2011 beta test season the controls team tested CAN and 2CAN in a variety of situations. Unfortunately we were not able to use CAN or 2CAN on our 2012 robot 'Thermite' due to unknown issues with these systems and the pneumatics. During the 2012 summer we believe we have resolved this issue and plan to continue experimentation.