AXP340 discrete air/ground switch

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   I saw this in an earlier (I think) IFD540 IM.
For those installations that use a combined IFD540 – AXP340 Mode S ADS-B transponder, the on-ground/in-air discrete signal wire may need to be added from the IFD540 tray to the
AXP340 tray as identified in Section 6.15.

I didn't see this paragraph in the current 540 IM.  

Is there a way for the 340 to automatically switch from ground to air mode other than a squat switch?  I was hoping I could get a signal from the 540 to do that function.  Maybe based on ground speed?

Jim
N2247X

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jimelliott Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 30 Mar 2014 Location: Alabama Status: Offline Points: 12	Post Options Post Reply Quote jimelliott Report Post Thanks(0) Quote Reply Topic: AXP340 discrete air/ground switch Posted: 20 Nov 2014 at 3:30pm
	I saw this in an earlier (I think) IFD540 IM. For those installations that use a combined IFD540 – AXP340 Mode S ADS-B transponder, the on-ground/in-air discrete signal wire may need to be added from the IFD540 tray to the AXP340 tray as identified in Section 6.15. I didn't see this paragraph in the current 540 IM. Is there a way for the 340 to automatically switch from ground to air mode other than a squat switch? I was hoping I could get a signal from the 540 to do that function. Maybe based on ground speed? Jim N2247X
	Jim Elliott

AviJake Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 26 Mar 2009 Location: Lincoln MA Status: Offline Points: 2815	Post Options Post Reply Quote AviJake Report Post Thanks(0) Quote Reply Posted: 20 Nov 2014 at 3:34pm
	Jim, Standby up to a few days on that answer. There is some internal confusion and some of the folks who can help answer this with complete certainty are away on travel. There is a air/ground output discrete of the IFD540. That was intended to be used for exactly that purpose (e.g. a device can use that output discrete to toggle a ground/air transition instead of needing a squat switch). I need to make sure that was implemented correctly across the board.
	Steve Jacobson sjacobson@avidyne.com

Gring Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 30 Dec 2011 Location: Kingston, NY Status: Offline Points: 737	Post Options Post Reply Quote Gring Report Post Thanks(0) Quote Reply Posted: 20 Nov 2014 at 4:19pm
	I can tell you from experience that I flew with another AviLive user with dual IFD540s and the AXP340 transponder. His automatically switched from GND mode to ALT mode and was using the IFD540 to make that happen rather than a squat switch. My installation powers up on ALT mode all the time, so I must not have some of that special wiring because our software configuration settings were the same.

tony Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 06 Dec 2011 Location: Atlanta Status: Offline Points: 466	Post Options Post Reply Quote tony Report Post Thanks(0) Quote Reply Posted: 20 Nov 2014 at 7:43pm
	The installation manual shows P1001 pin 8 as a weight on wheels output. On page 175 the manual shows this signal interfaced to the transponder as a squat switch. My question is, can I parallel the outputs? Is the output a dry contact? In other words can I run pin 8 from each IFD to the same pin on the transponder? Edited by tony - 21 Nov 2014 at 5:29am

jimelliott Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 30 Mar 2014 Location: Alabama Status: Offline Points: 12	Post Options Post Reply Quote jimelliott Report Post Thanks(0) Quote Reply Posted: 21 Nov 2014 at 1:16am
	Great feedback. Thanks guys!
	Jim Elliott

jimelliott Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 30 Mar 2014 Location: Alabama Status: Offline Points: 12	Post Options Post Reply Quote jimelliott Report Post Thanks(0) Quote Reply Posted: 21 Nov 2014 at 1:30am
	With information from Tony's post I found this in the IFD540 IM Table 54 regarding ADS-B transponder output. Connect the appropriate input pin on the AXP340 with the IFD5XX P1001 Pin 8 in order to get automatic on-ground / in-air mode transition. I will be sure to share this with my installer.
	Jim Elliott