Installation knowledge

Connecting Becker RT6201 and RT6211 to the SD-Link AR620X

The SD-Link AR620X brings SkyDemon, Sky-Map, VFRnav, and EasyVFR to Becker 6200 series radios. For the AR6201, AR6203, and AR6211, you simply plug it in between the existing unit and the radio. The RT6201 and RT6211 are remote transceivers without a built-in control unit – the adapter works the same way for these, but it's not plug-and-play: it requires four wires from connector J1 to the adapter. This page shows which ones.

Background

Two buses for two control units

All devices in the Becker 6200 series communicate with their control units via two serial buses on connector J1, which Becker calls "Secondary control & service interface" and "Auxiliary control interface", while installers refer to them as TMAP bus 1 and TMAP bus 2. The SD-Link AR620X registers on one of these buses as a second control unit and thus sets the frequency from the app.

That's why the AR6201 is plug-and-play and the RT6211 is not.

In the AR6201 / AR6211, the built-in control unit is internally connected to TMAP bus 2 (J1-2, J1-3, J1-9, J1-10). These pins appear unused on the connector, but are assigned. TMAP bus 1 (J1-7, J1-8, J1-14, J1-15) is intended for a second control unit and is free – the adapter uses it and is powered by it. Connector J1 remains unused; you simply plug the adapter in between. The RT6201 / RT6211 does not have a built-in control unit: The remote control unit (RCU) is connected to one of the two buses via J1, and the adapter requires the other.

wiring

Four lines from the free TMAP bus to the adapter

First, check which bus is still free on your RT6201 / RT6211. Then connect the four wires of this bus to pins 7, 8, 14, and 15 of the SD-Link adapter. That's all that's needed, including no additional power supply.

  1. TMAP bus 1 is free: connect 1:1 J1-7 → Pin 7 · J1-8 → Pin 8 · J1-14 → Pin 14 · J1-15 → Pin 15
  2. Only TMAP bus 2 is free: connected J1-2 → Pin 7 · J1-3 → Pin 8 · J1-9 → Pin 14 · J1-10 → Pin 15
  3. Activate TANDEM mode on the radio The device only accepts a second control unit in TANDEM mode. The steps are described in the SD-Link AR620X Installation Guide.
  4. Set up in the app Add the adapter directly in SkyDemon (or Sky-Map, VFRnav, EasyVFR), not in the Bluetooth system settings, and select the entry for Becker AR620X.
Both buses occupied?

If two keypads are already connected to the RT6201 / RT6211, no bus is free and the adapter cannot be connected. This is rare; if in doubt, send us a photo of the wiring to info@sdlink.de.

Practice

From the installation

A common mistake on the first attempt: The four wires are connected to the pins of the occupied bus (for example, J1-2, J1-3, J1-9, J1-10 on a device whose RCU is located there). Then nothing happens. With the free bus, the adapter works immediately – as was recently the case with an RT6211 in a vintage warbird, where only the pin assignment was missing.

Frequently asked questions

Questions about the RT6201 / RT6211

Does the SD-Link AR620X work with the Becker RT6201 and RT6211?

Yes. The SD-Link AR620X uses the same control unit interface as the AR6201, AR6203, and AR6211. However, installation is not plug-and-play for the RT6201 and RT6211: four wires from a free TMAP bus must be connected from connector J1 of the radio to the adapter.

Why is the installation on the RT6201/RT6211 not plug-and-play like on the AR6201?

The AR6201 and AR6211 have a built-in control unit that is internally connected to TMAP bus 2. The second bus (TMAP 1, pins J1-7, J1-8, J1-14, and J1-15) is reserved for a second control unit and is normally unused; this is where the SD-Link adapter registers as the second control unit. The RT6201 and RT6211 are remote transceivers without a built-in control unit: their control unit (RCU) is connected to one of the two buses via J1, and the adapter requires the other.

Which pins do I need to connect?

If TMAP bus 1 is free: J1-7 to pin 7, J1-8 to pin 8, J1-14 to pin 14 and J1-15 to pin 15 of the adapter, i.e. 1:1. If TMAP bus 2 is free instead: J1-2 to pin 7, J1-3 to pin 8, J1-9 to pin 14 and J1-10 to pin 15 of the adapter. No more wires are needed.

Does the adapter require its own power supply?

No. The SD-Link AR620X is powered via its four bus lines. Additional power lines are not required.

What is the TANDEM mode and do I need to turn it on?

Yes. In TANDEM mode, the radio accepts a second control unit on the other bus. Without this mode, the device ignores the adapter. Instructions on how to activate it can be found in the SD-Link AR620X installation manual.

What happens if both TMAP buses are already occupied?

Then no connection is possible: The adapter needs a free bus. This is the case if two control units are already connected to the RT6201 or RT6211.

Does this also apply to AR6201, AR6203 and AR6211?

No. With these devices, you simply plug the adapter in between the radio and the wiring harness; connector J1 remains unused for the adapter. The adapter works plug-and-play.

SD-Link AR620X

An adapter for AR6201, AR6203, AR6211, RT6201 and RT6211 – manual with TANDEM mode and pin assignment included.

Regarding the SD-Link AR620X AR620X manual All radio equipment