Autopilot servo wiring to iEFIS via CAN

[Phil Ayrton]

My aircraft has all MGL equipment, including a single Challenger iEFIS and autopilot servos using CAN bus for communications. It’s wired using the CAN bus layout shown as an example in the iEFIS manual. CAN buses 1&2 are connected into the iBOX using the pins described in the installation manual and as listed adjacent to the 9pin D sub connector marked for CAN interface. CAN bus 1 has compass, AHRS and RDAC and CAN bus 2 has a roll servo, a pitch servo and Garrett transponder and are both fitted with the required terminators.

I’ve got everything else working except the autopilot. The servo LED lights show solid red indicating they have power but no communications.

The CAN wires at the servos are connected to pin 8 (low) and pin 9 (high) as required but I also notice the autopilot wiring diagram for CAN interface, (figure 2, page 5 of the servo spec. and installation manual, dated 20 October 2010) is expecting the CAN wires to be connected to pin 2 (high) and pin 3 (low) at the iEFIS but as this is CAN bus 2 it is actually connected to pin 3 (high) and pin 4 (low) as required by the iBOX installation instructions .......is there something I’m missing here?? Maybe there is a revised wiring diagram I need for wiring autopilot servos to the iBOX....??

Thanks for your help
Philip Ayrton
Australia

[rainier]

Before you can use a servo it needs to be told what it is.
You must connect ONE servo at a time and then use the Servo identification in the AP setup menu (for the selected function for that servo) to assign it. Once you do that the servo LED will start flashing.
This is stored in the servo itself - once a servo knows that it is a bank servo for example it will react to bank servo commands only. You can reassign a servo that has been assigned before at any time.
It is important to only assign one servo at a time as any servo that is connected will be set to the function you select.

[Phil Ayrton]

Thanks for that, l have tried to do that, When l disconnect one servo and use the identification menu l can’t get to the selections shown in the manual, they aren’t available.....does it sound like I’ve wired it correctly (meaning the Figure 2 on Page 5 of the servo specification and installation manual is incorrect) this might affect other builders in the future.
I’ll try the procedure again tomorrow and report what messages l get or where it stops in the screen menus.....
Thanks again for your help
Phil

[rainier]

If those items are disabled it simply means your EFIS is in flight mode. It does not allow you to mess with the servos if it thinks it is busy flying.
If you are in manual flight detect mode - use the action menu to cancel the flight.
Also make sure your airspeed reads zero - it will also suppress if you are showing airspeed.

[Phil Ayrton]

Can l clarify one point please,
I’ve used the example layout shown in the iEFIS Panel Installation Manual, this shows CAN bus 2 being used for roll servo, pitch servo and transponder, but I’ve just noticed the Integrated Autopilot User and Installation Manual on page 14 in Ground Based Configuration of the Autopilot System says “If more than one CAN interface exists, CAN interface 1 must be used”
Do l need to swap CAN 1 with CAN 2 at the iBOX and if so what will happen to my transponder settings??
Thanks again
Phil Ayrton

[rainier]

You can use any of the two CAN bus systems.

[Phil Ayrton]

Rainier, just wanted to let you know l got it working, there were a number of issues, I changed it to auto mode for flight select to make it didn’t think it was flying and the other issue was the power source coming from my Vertical Power system showing faults and that took a while to get sorted out but l eventually got there, so thanks again for your help.
Philip Ayrton
Wollongong, Australia