Van's Air Force
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GSA 28 wiring question
- Thread starter SteveRV8
- Start date
Spark chaser
Member
All you need is a 22ga power wire to pin 10
GRD at pin 9
Twisted shielded pair to CAN buss pins 1 and 2
CWS/ Disconnect pin 15
Jumper pitch strap pins 5 and 8
Jumper CAN strap pins 3 and 4 if located at end of CAN buss
GRD at pin 9
Twisted shielded pair to CAN buss pins 1 and 2
CWS/ Disconnect pin 15
Jumper pitch strap pins 5 and 8
Jumper CAN strap pins 3 and 4 if located at end of CAN buss
Great advise !
The wings on the 8 are pretty short and very accessible when installed.
I wired mine after the wings were painted and installed , no problem .
Also the Garmin wireing is a good at home , evening job . I made 95% of the harnesses that way .
GSA28 Roll Servo Wiring
Hello Steve,
We agree with the others that it is generally best to just mount the servo bracket and wait on the wiring when possible.
Page 20-6 of the Rev. M G3X Installation Manual shows the wiring requirements for the roll servo.
Without the GMC305 and auto-trim, it is very simple. A 22 AWG twisted shielded pair of wires for the CAN bus connect to pins 1,2 and 22 AWG wires for power and ground connect to pins 10,9. The CWS/DISC button single 22 AWG wire connects to pin 15.
For many installations, the roll servo is at the end of the CAN bus, so a CAN termination jumper is installed by crimping pins on a short piece of 22 AWG wire and inserting these pins into positions 3,4. When installed at the end of the CAN bus, you also terminate the CAN bus shield on the backshell of the roll servo.
Let us know if you have additional questions.
Thanks,
Steve
Hello Steve,
We agree with the others that it is generally best to just mount the servo bracket and wait on the wiring when possible.
Page 20-6 of the Rev. M G3X Installation Manual shows the wiring requirements for the roll servo.
Without the GMC305 and auto-trim, it is very simple. A 22 AWG twisted shielded pair of wires for the CAN bus connect to pins 1,2 and 22 AWG wires for power and ground connect to pins 10,9. The CWS/DISC button single 22 AWG wire connects to pin 15.
For many installations, the roll servo is at the end of the CAN bus, so a CAN termination jumper is installed by crimping pins on a short piece of 22 AWG wire and inserting these pins into positions 3,4. When installed at the end of the CAN bus, you also terminate the CAN bus shield on the backshell of the roll servo.
Let us know if you have additional questions.
Thanks,
Steve
Thank you for the replies/info. I did reference the install manual and needed clarification. I feel confident in basic A&P electrical work but these new systems with CAN busses and such do intimidate me at this point. If I use the roll servo as a termination point do you suggest running the CAN bus to the pitch servo and then back to the roll servo, with the other termination point behind the panel? Is there any concern running the CAN bus or other servo wires with the rest of the wires going to the wingtip lights?
Hello Steve,
Yes, it is fairly common to run the CAN bus to the pitch servo, then over to the roll servo where the CAN bus ends and is terminated (using the jumper on the servo described above).
The CAN bus is frequently started at the PFD. As shown on page 20-2 of the Rev. M G3X Installation Manual, simply connecting pin 28 to pin 45 on the PFD connector enables the CAN bus termination at that end.
Don't let the CAN bus intimidate you. It is simply a twisted, shield pair of wires that runs around the plane and connects all the G3X devices which have a CAN interface. It is terminated only at each of the extreme ends of the bus, quite often at the PFD and roll servo.
Even though the wiring running to the roll servo is shielded, we recommend not running the servo wiring in the same bundle with the wingtip wiring if the wingtip includes a strobe.
You may contact us anytime via email or phone if you have additional installation questions.
Thanks,
Steve
I'm about the light this candle with a G3X installation, and I'm a bit confused about CANBUS wiring. I see notes in the install manual diagrams about CANBUS wiring not to exceed 1M - what's that all about?
Also, in my RV-8, I have just installed Whelen Orion 600 nav/strobes and LED landing lights, which do not *require* shielded cable, but I used it anyway. The cabling runs inside the wing conduit, and I plan to use the conduit to run the cabling to the roll servo. Will this be a problem? BTW, the Orion nav/strobe and the LED landing lights replaced an old, noisy Whelen nav/strobe xenon and H3 landing lights.... The new setup is absolutely radio/intercom silent.
Hello maus92,
Good questions.
The 1 meter maximum length specified for the CAN node length has some theoretical value, but it has little value in the real world for those of us wiring airplanes.
As described above and in many other postings on VAF, the shielded pair CAN bus should be daisy-chained from one device to the next throughout the plane, keeping the wires going from the main CAN bus to the device connector (the node) as short as practical - which generally means a couple of inches.
The real guidance on node length is in the first paragraph of section 2.3.1.3 which states "keeping the node length as short as practical is recommended".
We will probably be removing that 1 meter guidance from the installation manual since it seems to add more confusion than value. There is no length limitation between devices on the CAN bus that are daisy chained together, and some customers try to interpret the 1 meter node limitation as applying to distance between devices, which isn't accurate.
We have seen some large harnesses that had a CAN backbone up to 70 ft long and this is no problem when the CAN bus is daisy chained to each device and properly shielded and terminated (at each end).
You can get into trouble if you turn the CAN bus into a "star" network by connecting several devices to the same general section of the main CAN bus (such as with a hub), so we always tell builders to ignore the 1 meter limitation, and just daisy chain the CAN bus to each and every device in a serial fashion throughout the plane and you will be fine.
As stated in the previous post, we prefer to keep the CAN high speed data bus from sharing a wiring conduit or wiring bundle with strobe wiring, but you are welcome to give it a try.
We have built-in diagnostics that displays the CAN error rate from PFD1 to each device on the CAN bus, so you could test turning on/off the strobes and see if there is any measurable impact should you decide to share that conduit. Except during power up/down of devices on the CAN bus, any error rate that exceeds 0% is considered unacceptable. CAN bus data errors will be non-existent in a good installation.
Thanks for choosing G3X!
Steve
Check6
Well Known Member
RV8 roll servo mounting
Does anyone have any pictures and/or insight gained on installing the garmin roll servos in the 8 for the G3X touch system? This will be a panel redo and not a new build. So how challenging was it running wires etc. Any pictures of this project would be great!
Thanks,
Does anyone have any pictures and/or insight gained on installing the garmin roll servos in the 8 for the G3X touch system? This will be a panel redo and not a new build. So how challenging was it running wires etc. Any pictures of this project would be great!
Thanks,
Robert Anglin
Well Known Member
Manual !
The manual is the best place to get your head around this, although it can be a little intimidating. Give it some time and it will start making sense to you.
We founded that in the RV-8 it was best to use the roll servo at one end of the CAN buss and the pitch servo at the other end of the CAN buss, with everything along the CAN in the meddle of the buss line "if you will". We did not have any problems with EMI in the right wing with that servo, but did with the magnetometer in that wing. The answer we found was simple. Run a ground wire from the wing tip of the right wing all the way back inside to the center section of the air frame. With that ground lead not attached to the metal of the wing at the tip end "insolated". This did not allow current to run through the structure of the wing and so no EMI out in that wing. The nodes as you will see can be made-up in a number of ways. We just soldered a short peace of AWG-20 to the spot we wanted to make a splice-in for a box to be connected to the CAN. Then heat shrunk the slice and cut the short peace of AWG-20 to fit just long enough to clear the strain relief bar on the back shell. It works very well and is simple and strong. Just what we did.
Hope this helps. Yours, R.E.A. III #80888
P.S. I forgot everything get to go to that ground lead in the wing, lights strobe, servo ground, Ext.
The manual is the best place to get your head around this, although it can be a little intimidating. Give it some time and it will start making sense to you.
We founded that in the RV-8 it was best to use the roll servo at one end of the CAN buss and the pitch servo at the other end of the CAN buss, with everything along the CAN in the meddle of the buss line "if you will". We did not have any problems with EMI in the right wing with that servo, but did with the magnetometer in that wing. The answer we found was simple. Run a ground wire from the wing tip of the right wing all the way back inside to the center section of the air frame. With that ground lead not attached to the metal of the wing at the tip end "insolated". This did not allow current to run through the structure of the wing and so no EMI out in that wing. The nodes as you will see can be made-up in a number of ways. We just soldered a short peace of AWG-20 to the spot we wanted to make a splice-in for a box to be connected to the CAN. Then heat shrunk the slice and cut the short peace of AWG-20 to fit just long enough to clear the strain relief bar on the back shell. It works very well and is simple and strong. Just what we did.
Hope this helps. Yours, R.E.A. III #80888
P.S. I forgot everything get to go to that ground lead in the wing, lights strobe, servo ground, Ext.
Last edited:
Robert Anglin
Well Known Member
Manual !
The manual is the best place to get you head around this, although it can be a little intimidating. Give it some time and it will start making sense to you.
We founded that in the RV-8 it was best to use the roll servo at one end of the CAN buss and the pitch servo at the other end of the CAN buss, with everything along the CAN in the meddle of the buss line "if you will". We did not have any problems with EMI in the right wing with that servo, but did with the magnetometer in that wing. The answer we found was simple. Run a ground wire from the wing tip of the right wing all the way back inside to the center section of the air frame. With that ground lead not attached to the metal of the wing at the tip end "insolated". This did not allow current to run through the structure of the wing and so no EMI out in that wing. The nodes as you will see can be made-up in a number of ways. We just soldered a short peace of AWG-20 to the spot we wanted to make a splice-in for a box to be connected to the CAN. Then heat shrunk the slice and cut the short peace of AWG-20 to fit gust long enough to clear the strain relief bat on the back shell. It works very well and is simple and strong. Just what we did.
Hope this helps. Yours, R.E.A. III #80888
The manual is the best place to get you head around this, although it can be a little intimidating. Give it some time and it will start making sense to you.
We founded that in the RV-8 it was best to use the roll servo at one end of the CAN buss and the pitch servo at the other end of the CAN buss, with everything along the CAN in the meddle of the buss line "if you will". We did not have any problems with EMI in the right wing with that servo, but did with the magnetometer in that wing. The answer we found was simple. Run a ground wire from the wing tip of the right wing all the way back inside to the center section of the air frame. With that ground lead not attached to the metal of the wing at the tip end "insolated". This did not allow current to run through the structure of the wing and so no EMI out in that wing. The nodes as you will see can be made-up in a number of ways. We just soldered a short peace of AWG-20 to the spot we wanted to make a splice-in for a box to be connected to the CAN. Then heat shrunk the slice and cut the short peace of AWG-20 to fit gust long enough to clear the strain relief bat on the back shell. It works very well and is simple and strong. Just what we did.
Hope this helps. Yours, R.E.A. III #80888
