G3X (GAD27) Discrete Input for Frequency Swap

I'm trying to understand about the operation of the GAD27 discrete inputs relative to the frequency swap function. The G3X installation manual has the following statement:

COM Freq Swap - Used with a GMA 245/245R audio panel and a connected COM radio to swap the active and standby frequencies on the currently selected COM. The audio panel's selected microphone channel is used to determine which radio receives the frequency swap command.

While I don't have a GMA 245/245R I do have a GTR200 and a GNS430W. I had planned on running a separate wire to these devices for the frequency swap or frequency transfer function. However if there was some way of using a discrete on the GAD27 that would be convenient since I plan to have the GAD27 mounted near my sticks which will have a button assigned to this function.

If anyone could provide some clarification on what this discrete input assignment does that would be very helpful because the paragraph in the install manual isn't very informative to me.

Unless I am seriously mistaken, if you feed the discrete input into the GEA24 or the GAD27, the communications to the com radio will be via the CANbus and you should not need to feed into the discrete input on the COM. I made the mistake when wiring my panel of feeding the discrete input from my control stick straight into the COM, which means I can't utilize this button for any other function in the future if I change my mind on what I want to utilize it for.
I'll see if I can find the specific section in the manual where this is addressed, unless someone chimes in before hand.

Cheers,

Tom.
RV-7

Tom,

This is what I was thinking they were implying. That would mean that it wouldn't swap frequencies on my GNS430.

So does that mean it somehow uses knowledge of which radios are connected to COM1 or COM2 to decide which radio to send the frequency transfer command to? That could actually be nice but it does imply that that all of those devices would be required.

Hi Ray,

I've read through pretty much everything in the manual, and I can't find anything yet that allows you to use the discrete inputs in the GAD27 or GEA24 to perform the com flip flop function (or any other discrete input function for the radios). I assume you have a GEA24 also?
I'll be back at the hangar tomorrow and will boot up the configuration mode and run through the discrete input options. This will pretty quickly tell us if it's a possibility or not.
Will report back tomorrow.
Tom.

rapid_ascent said:

I'm trying to understand about the operation of the GAD27 discrete inputs relative to the frequency swap function. The G3X installation manual has the following statement:

COM Freq Swap - Used with a GMA 245/245R audio panel and a connected COM radio to swap the active and standby frequencies on the currently selected COM. The audio panel's selected microphone channel is used to determine which radio receives the frequency swap command.

While I don't have a GMA 245/245R I do have a GTR200 and a GNS430W. I had planned on running a separate wire to these devices for the frequency swap or frequency transfer function. However if there was some way of using a discrete on the GAD27 that would be convenient since I plan to have the GAD27 mounted near my sticks which will have a button assigned to this function.

If anyone could provide some clarification on what this discrete input assignment does that would be very helpful because the paragraph in the install manual isn't very informative to me.

Click to expand...

Hello Ray,

This is a nice G3X Touch feature, but it requires two things to work.

First, you need a GMA 245/245R audio panel. This is needed because the G3X Touch system needs to know which of the 2 COM radios are currently selected and active on the audio panel. The GMA 245/245R audio panels communicate with the G3X Touch system at a high level and tell the system which COM radio is currently selected to the PTT/Microphone function. Since your present installation does not have a GMA 245/245R audio panel, your G3X Touch system has no idea which COM is currently active.

Secondly, your COM radios need to be of a type that the G3X Touch can communicate with and command to swap the active and standby frequencies. Table 35-19 on page 35-148 of the Rev. AM G3X Touch installation manual shows the 6 radios that have this capability. The GTR 200 does, but the GNS 430W does not.

Here is an example screen shot for a G3X Touch system with this capability. You can see that the COM1 active frequency is shown in green, so the GMA 245/245R audio panel has told the G3X Touch system that COM1 is currently selected for transmission when the PTT button is pressed. If you press the COM Freq Swap button, the active/standby frequencies are automatically swapped for the selected (active) COM radio whether that be COM1 or COM2. This is all done with a single discrete input and stick button.



Steve

Steve,

Thanks for the clarification. Yes that would be a really cool feature. You're explanation should probably go in the manual since it explains what I thought might be the case. It might even help sell some more new hardware. It almost makes me want to migrate in that direction myself. In my current configuration with 2 radios I can't really swap frequencies on the selected radio with a single button.

If I had a GMA245 with my GTR200 as COM2 would that allow these control features at least on COM2?

BTW I think there is an error in section 26.1.5. It says: To terminate the CAN bus at the GAD 27 short the pins (2 and 3) together. I think this should be pins 3 and 4. Also there is no mention of the Signal Ground pin in these tables.

Hi Ray,

I checked the configuration menu in the G3X (10" touch) and sure enough, for the digital input configuration for both the GAD27 and GEA24 there is the option to configure one of the digital inputs as a COM frequency swap. I suspect that this frequency swap command is transmitted to the respective COM over the CANbus, so it will likely only work with your GTR200. As you point out though, you may need an GMA245, although this seems a little odd since the G3X can run a GTR200 by itself without a GMA245 like the others have stated. I have a GMA245, but if I was to do things again, I probably wouldn't have. I really only got it because of the bluetooth, and now that the GTR200 comes with bluetooth (along with pretty much every headset you buy these days) I would have preferred to save the weight and complexity. With the bluetooth, frankly there's your standby com. I have the two control towers in our region saved in my phone on speed-dial incase I ever lose coms, so between this and the ability to monitor the standby frequencies on the GTR200, you'll probably find you never use the GNS430W for a com radio. The ability to send frequencies straight from the G3X (or Aera660/760 if you have one) to the GTR200 is also an awesome feature, as it allows you to just click on the airfield, select the required frequency and bang it through to the standby frequency. Finally though, it is still speculation that using the GAD27 or GEA24 discrete input as frequency swap will work as I have not verified it, so your safest bet is likely wiring the discrete input directly to the GTR200.


Cheers,

Tom.

Com Swap with GMA345

Is it correct to assume that with a GMA345 audio panel, the COM SWAP function has to be wired directly with the GMA345 pin 20 (J3402 connector)?

Or can I wire it to the GAD27 / GEA24 discrete input as the GMA345 talks to the PFD via serial bus?

Igor,

From what I understand this feature is only supported for the 245 over CAN. Refer to the referenced manual section above.

rapid_ascent said:

Igor,

From what I understand this feature is only supported for the 245 over CAN. Refer to the referenced manual section above.

Click to expand...

Ray, that makes sense!

thanks,

supik said:

Is it correct to assume that with a GMA345 audio panel, the COM SWAP function has to be wired directly with the GMA345 pin 20 (J3402 connector)?

Or can I wire it to the GAD27 / GEA24 discrete input as the GMA345 talks to the PFD via serial bus?

Click to expand...

Igor,

Are you asking about the "COM Freq Swap" input discrete function discussed above which swaps the active/standby frequency for the currently selected COM radio, or a "COM Swap" function performed by the audio panel which swaps the selected radio between COM1 and COM2 (and has nothing to do with frequency)?

In either case, the answer is yes, assuming you have the right COM radios installed as discussed above (for the COM Freq Swap function).

If you have a GMA 345 audio panel wired over RS-232 like shown on page 27-47 of the of the Rev. AM G3X Touch Installation Manual, you can configure the "COM Freq Swap" GEA 24/GAD 27 input discrete function discussed above.

You can also install a separate button connected to GMA 345 connector J3402, pin 20 to perform the COM Swap audio panel function if desired.

Steve