Would This Work?

Two CM11As will coexist without problems.

With two transceivers it depends >2 CM11s programmed the same in different parts of the house? Or 2

Dave, I recognized the model you mentioned but after looking at my transceivers, the 751 doesn't have the unit codes, the RR501 does. Did you mean 501, not 751? Thanks, Joe

I think he meant that you can't set any units to those two codes when using dual TM-751's without a danger of collisions.

-- Bobby G.

No, I meant the TM751.

While they may have since changed things, X10 apparently used the same (or nearly the same) firmware routines in both the TM751 and RR501 when I tested this a few years back. Both use an SCR to toggle the relay and an SCR can only be triggered during a positive half-cycle of the mains voltage. Relays can only be assigned as units 1 or 9.

The relay is triggered before sending to the powerline so they need to wait for a rising ZC signal to trigger the relay. This puts them 180° out-of-phase with any transceiver on the opposite phase. For other unit codes, they all transmit on the next ZC, regardless of polarity.

For the RR501, there have been a few different versions with different capabilities. From about the time the CM11A was introduced, the RR501 has had collision detection & automatic retransmit. This complicates things, leading to duplicates of some commands but not others.

The Leviton all housecode version (HCPRF) also has collision detection and automatic retransmit and can use any of 256 addresses for its relay but I have not tested whether it cares about polarity.

All in all, the TM751 is easier to explain and to use in this way.

Some older transceivers with brown cases (model?) and some security base stati>Dave, I recognized the model you mentioned but after looking at my

I've always learned to ask to make sure I'm reading right. (-:

Does this mean you get collisions just for sending the unit 1 or 9 codes, even by accident? This might explain some weird behavior I am seeing in that twin TM751's set to the same housecode activate in sequence - I can hear the living room one click first and then the bedroom one if I press B1 "ON" on an RF remote. It's always a definite, same delay between the activations and I have to mash down on the button to get the second one to click. Not sure I can tell what phase they are on, though without flipping breakers and that's a sore subject still around my house!

-- Bobby G.

Whether intentional or not, once the transceiver receives/decodes the RF, it sends it to the powerline (after waiting for a positive ZC if unit 1 or 9).

If on opposite phases, for units 1 & 9, one will lag the other by 1/2 cycle (1/120s or 8-1/3ms) which guarantees a powerline collision.

I doubt you are able to discern an 8ms difference >I've always learned to ask to make sure I'm reading right. (-:

activations.

(goes to check to settings and PIC codes)

There's a third explanation!!! Hmmm, color my face red. The module controlling the powermid in the bedroom is an appliance module. I just moved the damn very heavy bed to make sure of the PIC version of the TM751 and miraculously, it morphed into an appliance module before my eyes! Damn that X-10!!!

I guess my item/location database was wrong. Thanks for not calling me too big of an idjit. D'oh. The delay I heard was the TM751 receiving the RF and clacking on and then putting B1 on the powerline via the appliance module. That's a delay that's quite apparent. Oy, do I feel dumb.

-- Bobby G.

They're called Senior Moments. Treasure them while you can still remember them.

Senior hours and days are more like it! (-:

-- Bobby G.