Multiple X10 RF Transceivers, same housecode

[Stevech]

Is this correct...
If there are multiple X10 RF Transceivers (TM751 or RR501) on the same house code, and if both hear the same wireless message, they may or will often transmit X10 on the power line simultaneously and perhaps jam out one another due to mis-timing.

[jkarney]

The RR501 X10 RF receiver is polite and will check the power-line to ensure it no X10 signals are present before transmitting an X10 signal. So if there was 2 RR501 RF receivers on the same house code you would only get duplicate X10 signal transmissions to the power-line.

As for the TM751 it is considered not polite as it will transmit to the power-line without checking the power-line to see if an X10 signal is present. Of course this could result in a signal collision.

Differences between RR501 and TM751

RR501

Two-way module/receiver which will act on X10 line signals as well as RF signals
The "appliance-like" module receptacle can be set to either unit 1 or 9
Can be polled for "status"
Has collision avoidance

TM751

Will only react to RF signals, not X10 line signals. it will however still put the 16 unitcode signals for one house code on the line (when instructed to by X-10 RF)
can only be unit 1 (not changeable).
Cannot be polled for "status"
Does not have collision avoidance

Hope this helps!

Jim

[Stevech]

Yes, thanks very much, Jim.

I'm the nth person to try to get 310MHz coverage in/near my home with X10 stuff in the junk box, while trying to avoid buying a more costly/better receiver.