September 16, 2010

Wiring Change for SkyView Software Version 2.6 Update

New in SkyView version 2.6 software, serial port outputs from multi-screen SkyView systems must be connected together. This change adds redundancy to the system when interfacing to serial devices.

Who this Affects

The changes are required for existing SkyView systems, and all new installations that:
  1. have multiple SkyView displays AND
  2. are transmitting to a serial device. (Today, this includes altitude output provided by SkyView for use with transponders, the Dynon SV-XPDR-26X mode-S Transponders, and other RS-232 outputs SkyView is capable of) AND
  3. are running running 2.6 or later software

In SkyView 2.5 and earlier, external serial devices that can transmit have their TX wires hooked to a serial RX on all SkyView displays in parallel. In the other direction, if an external serial device can receive serial data from SkyView, its serial RX is hooked to only one display's serial TX. This is how serial devices are classically set up: they can transmit to multiple receivers, but can only receive from a single transmitter. This limitation is necessary, otherwise a single receiver would hear only noise as the two competing transmitters essentially talk over each other. SkyView 2.6 overcomes this limitation by smartly turning each display's transmitters on and off as appropriate. This allows devices like the SV-XPNDR-26X, other transponders that receive altitude from SkyView, and other devices to have their serial RX lines connected to multiple SkyView displays simultaneously. SkyView, silently and seamlessly, picks a display to transmit from. Should that display fail, the other display takes over automatically. This allows these devices to continue to receive data, even in the event of a display failure. In SkyView 2.5 and earlier, if the single display that is set up as the serial transmitter fails, the device that is connected to it will no longer receive any serial data.

Action Required

This change means that slight wiring changes will be required in some systems. All devices that have the ability to receive serial data should have their serial RX wired in parallel to a serial TX on all SkyView displays in the system. Each display must then be set up to transmit to the device under the SETUP MENU > LOCAL SCREEN SETUP > SERIAL PORT SETUP. Dynon suggests using the same serial ports on each display, essentially connecting each device serial RX to the same serial X TX on every SkyView display. This makes it easier to duplicate the settings across screens by using exactly the same serial port setup.

The above changes are REQUIRED with SkyView version 2.6 and above. However, the wiring must not be made BEFORE the 2.6 update either, as SkyView will not be able to correctly transmit to devices connected per the above instructions until 2.6 is loaded. Therefore, the above wiring changes should be made at the same time the aircraft is being updated to 2.6.

If the above changes are not made with the 2.6 update, devices that receive serial data from SkyView will only receive serial data some of the time. To the pilot, this will appear like a random failure of the altitude encoding functionality of SkyView, or the failure of the SV-XPNDR-26X module (if installed).