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Unread 18-01-2014, 04:05
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Levansic Levansic is offline
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AKA: Len Evansic
FRC #0585 (Cyber Penguins)
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Location: Tehachapi, CA
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Re: Disadvantages to CAN?

We've used CAN networked Jaguars for the last few years, and are planning the same this year. The biggest frustration we have had was the unreliability of the daisy-chain topology.

The locking RJ connectors will give you warm fuzzies on the bench, but they are devious devils on the field. We addressed this by changing the topology to a star, and using 6P6C pugs to minimize wiggling problems. Also, we keep a set of dental picks handy to "fix" the contact wires within the Jaguar jacks.

It is telling that the 2015 controller uses a two position wago-type wire clamping jack for the CAN-high and CAN-low wires. Hindsight being what it is, I wish the Jaguar was designed with the same arrangement.

One other thing to pay attention to, is the fact that Jaguars are little computers on their own. When the voltage drops too low, like when a few CIM's stall, they reboot. If you are using any closed loop control, this will be flushed, and the default voltage control will be what you will come back to. You have to devise your own recovery code to restore the mode and parameters, unless you are just using the default mode.

--Len
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