queryplc command

[pconroy]

I'm curious - how does (or how *did*) queryplc work?

Did the unit have a little NVRAM and keep track of the last state of a module?

I mean - I thought you couldn't ask a LM465 what it's state is?
The LM14's - yes - but not a Lamp or Appliance module.

I'm storing the last update sent in a mySQL database.
Cuz that's what I thought I had to do.

thanks!

[dbemowsk]

The CM15A remembers the state of modules that it controls.  There are drawbacks to that.  For instance, I have some WS13A wall switches in my house.  If I go and manually turn them on at the switch, the CM15A doesn't know that I did that because the WS13A didn't transmit a signal to it telling it that I activated it.  However, if I use AHP to activate it, the CM15A is what is turning it on or off and remembers it.  The same goes for an RF remote.  Since the RF remote runs through the CM15A, it can remember the state.

Hope that all makes sense

Dan B.

[-Bill- (of wgjohns.com)]

To expand on dbemowsk's explanation:

The CM15A itself remembers what it last sent out to each of the 16 X10 addresses in the "Monitored House Code".

The CM15A driver software on the computer remembers what it last sent to all 256 X10 addresses.

So, when you first boot the computer, the status of most X10 modules will be unknown and only the ones in the "Monitored House Code" will likely be correct, as the driver software can read those from the CM15A, but not the rest.

[pconroy]

<Ed McMahon Voice>

Thank you sir!
I did not know that!   

</Ed McMahon Voice>