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For 3 weeks an authorised Avidyne dealer has been trying to get our IFD 540 (only 9 months old and barely used) working with a new AXP322. They still haven’t succeeded and our plane is stuck hundreds of miles away from home in Guernsey. If anyone can help I would be very, very grateful. So far we have spent thousands of pounds on two amazing Avidyne products that just won’t work with each other.
I am certainly no avionics expert but people who are have tried the following to resolve the problem:
Warning “No Comm With Xpdr” alert flashing up and staying for about 4 seconds then clearing for about 2 seconds before reappearing.
• All configuration settings have been checked and approved by Avidyne.
• It is sometimes possible to be quick enough to switch it to Altitude but then it goes off again and when it comes back it is again in Ground Mode. • In configuration mode there is a continuous clocking up of the data of RS232 channel 2 in chunks of 5 bytes. This is quicker than every 2 seconds. This would suggest that the IFD is receiving data from the AXP but is still flagging the “No Comm With Xpdr” message. • A second AXP322 was flown from the USA in case the first was faulty. No luck. • Three different antennas have been tried. • The problem is independent of GPS lock. • A second IFD (a 440) was slaved in with the same results.
• All wiring has been checked and replaced. Continuity and insulation resistance of the RS232 lines and power and ground are ok. Tests indicate there is 13+V at the plug even with load on. • Tried powering the AXP from a 24v supply in case it was not liking the aircrafts 12V to no effect
• Current draw has been monitored and is a consistent 0.12-0.14A and seemed to jump up very briefly to 0.2+A when I managed to get it to ALT mode before it lost communication.
• Data can be seen on the RS232 Data line coming from the transponder continuously counting up without stuttering.
• Checked the Altitude and heading input from the G5 on EFIS/Air Data and that is good. • The problem is independent of whether the IFD has GPS WAAS lock or not. (The transponder occasionally reports No ADS-B when the GPS is lost suggesting it is receiving the GPS data at least some of the time.)
Is there a problem with the software level in the AXP of 2.1 (and 2.14) talking to the IFD which is on v10.3.1.2?
If we can’t get to the bottom of this soon I will have to ask Avidyne to replace both the IFD 540 and AXP322 under warranty, with the setup tested before shipping. Thanks in advance for any suggestions we haven’t tried.
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