Electronic – wireless door opening detection

The manual has the user using hyperterminal to send a text-file with the contents of + in it. I think the escape is just +, not +++. Also, you have to wait a few seconds (two is default) of no serial activity before the escape character will work.

I'm not sure if sending a text-file causes the terminal to behave differently then just typing +, or +++, but it might be worth trying. Maybe it needs basically no delay between the three +++, or it does something else (if the escape char is just +)

Also, have you checked that your signals are not inverted? Maybe the usb-serial is defaulting to normally high, and the module wants normally-low, or vice-versa.

Confirmed in comments below as three + characters, or +++. You have to send it as a text file. I suspect that feeding hyperterminal a text file causes the three bytes to be sent as close to each other as possible, while typing them manually causes a ~200ms+ inter-character delay (e.g. as fast as you can manually hit the + key).

Apparently the device has a much shorter "enter AT control mode" timeout them other similar devices, (like xBees, or such).

You could split data rate into two halves and use two separate Nordic modules for transmission and two separate modules for reception. Each pair can be set to transmit and receive on different channels.

It's not elegant but it halves the problem. I bet it would work with several pairs. Just a thought.