What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Signal wiring question CAN Bus

magiccarpet

Well Known Member
Patron
Hi all

I am helping a friend to replace his TruTrack A/P to a Dynon A/P on his RV-7A.
All CAN bus installation I have come across so far, needed twisted wires of CAN-H and CAN-L signals.
He would like to use the existing wiring through the fuselage. As far as I understand TT uses different control signals (4 per servo) to actuate the stepper motors.
I am concerned that using the existing non-twisted wires for the CAN bus will result in intermittent network node failures due to some sort of RF interference.
Am I too cautious here, or it is crucial to replace the signal wirings?

What is your opinion about using the existing control wires for hooking up the Dynon servos?
Thanks a lot for any suggestions here.
 
Dynon use a proprietary bus that uses twisted pairs and has two of them for redundancy, so thats two twisted pairs, plus the control wheel steering wire, power and ground.

That is seven wires total.

VV
 
If the current wiring setup doesn't have a twisted pair of wires for the CAN, you'll need to add it. You can't reliably use a non-twisted pair for CAN data.
 
As @vlittle said, no CAN bus in the Dynon system. Feel free to use existing wires.
 
As @vlittle said, no CAN bus in the Dynon system. Feel free to use existing wires.

Not a CAN bus. Dynon uses an RS-44X (can't remember that number ) protocol and it requires that the A & B pairs be twisted. similar protocol as that which ARINC uses. I do not recommend going against the recommendations of both Dynon and the committee that produced the standard. Shielding is not required. Note that std milspec 4 conductor wire does NOT have twisted pairs. All wires are twisted together and that is not the same. Best to roll your own (two wires twisted with a drill) or get the special milspec stuff that has twisted pairs (straight colors, not the white with colored tracers)
 
Last edited:
Back
Top