Serial Port Wiring

Hello All,

I have two 10" Skyview Displays and a VP-X. The VP-X manual shows to wire the serial port to both displays. Each display has a provided wiring harness and the serial lines are all non-shielded twisted pairs. I have already found comments from Dynon that they feel the serial lines do not need shielding even though the VP-X manual shows shielded. I Agree with Dynon and will not use shielding, but my question is going from one VP-X wire to each wire on the Dynons. One wire to two wires.

Can I use a crimp style splice here, or should I solder? I have a high end crimper that does a good job but would seek wisdom from the crowd that knows.

Thanks for the anticipated input.

Use a terminal strip like this, I shot this pic while installing mine. I've got dual 10" screens just like you and the serials need to connect to both screens. I tied the matching serials of the two screens together and fed them into the top, then the bottom connection runs to my chosen device for the serial connection. I mounted this directly on the subpanel and labeled it with a sharpy for future use.

drone_pilot said:

Hello All,

I have two 10" Skyview Displays and a VP-X. The VP-X manual shows to wire the serial port to both displays. Each display has a provided wiring harness and the serial lines are all non-shielded twisted pairs. I have already found comments from Dynon that they feel the serial lines do not need shielding even though the VP-X manual shows shielded. I Agree with Dynon and will not use shielding, but my question is going from one VP-X wire to each wire on the Dynons. One wire to two wires.

Can I use a crimp style splice here, or should I solder? I have a high end crimper that does a good job but would seek wisdom from the crowd that knows.

Thanks for the anticipated input.

Click to expand...

Crimping is fine for serial wiring and solder works as well. As long as you are using quality crimp terminals with proper tools, it is as good as solder. Pro's to solder are reduced corrosion. Pro's to crimping are reduced cracking due to wire movement.

Larry

airguy said:

Use a terminal strip like this, I shot this pic while installing mine. I've got dual 10" screens just like you and the serials need to connect to both screens. I tied the matching serials of the two screens together and fed them into the top, then the bottom connection runs to my chosen device for the serial connection. I mounted this directly on the subpanel and labeled it with a sharpy for future use.

Click to expand...

What's on the ends of those wires? Is there a ring terminal or something on there, hidden under the plastic?

No, it's got a small steel backing plate inserted into the plastic housing, and the steel screw pinches the wires down onto the backing plate for contact. The top and bottom of each section are connected by the same internal backing plate. The screw in the plastic is surprisingly high-torque so it won't back out under vibration. I put this directly behind my right-side screen for easy access later.

These are sold in the Avionics section of your local Lowes Hardware.

In any case, there are hundreds of variations of the terminal strip idea - pick one that floats your boat and head downstream with it.

Call me weird, but I'm just wondering how a bird cra**ed on your panel there?

Veetail88 said:

Call me weird, but I'm just wondering how a bird cra**ed on your panel there?

Click to expand...

Haha!! Nice catch...

My plane shares space with tractors and farming equipment, my family is all cotton farmers, birds inhabit the space. I try to keep everything covered and clean, but sometimes it happens....

I'm actually very proactive about cleaning it when it happens because I'm not sure what corrosive effects I might find later from the bird droppings.

airguy said:

No, it's got a small steel backing plate inserted into the plastic housing, and the steel screw pinches the wires down onto the backing plate for contact. The top and bottom of each section are connected by the same internal backing plate. The screw in the plastic is surprisingly high-torque so it won't back out under vibration. I put this directly behind my right-side screen for easy access later.

Click to expand...

That's what I thought.

This is not a good practice for aviation. Wires should have terminals crimped (or soldered, but crimping is preferred) on the ends and a more positive method of attachment to a terminal bus than just smashing wires under screws.

This is a failure-prone installation.

This problem is elegantly solved with a wiring hub. This allows you to connect all of the serial ports, audio signals and a few other signals from the SkyView to all of your other avionics using dsub connectors.

There's a schematic on the EFIS page of this document (document is an older rev but serves the purpose).

That's really neat Vern.

I've done something similar, but the hard way! All ARINC pairs to one 25 pin DSUB
All RS232 to another.
The other mating half of each DSUB jumpers the required pairs together.
Neat and secure
Cheers

I developed the printed circuit board shown to tie my dual Skyview system together and provide outputs to all the devices it covers. It is also my single point ground.

The 25 pin Dsubs go to the displays and contain all the serial, contact, gps, ADSB, Transponder, power and output wires that must be connected together. It uses two wires for Skyview power and ground. (Dsub connector pins are rated at 5 amps each).

The 9 pin Dsubs allow dedicated cables to each of the devices in the Skyview system:

Transponder
ADSB Receiver
GPS Antenna
Audio and Dimmer circuits
Spare Serial Port and all Contacts
Power in and contacts out. Power for the Skyviews, Transponder, ADSB Receiver, inputs from the aircraft, i.e., Autopilot disconnect, etc.

The two 36 pin connectors are all grounded to provide way too many common grounds. There are four tabs in the corners to connect the board to the aircraft ground.

There are solder points in most lands to pick up whatever I missed.

It is in my flying RV-10 and works well.

Circuit board

That is awesome Bruce.