CM12 Extended Codes

[John B]

Hi all,

I'm trying to get the CM12 to send out X10 extended codes (so I can set my
LD11s
to a direct level).

If I use the Homeseer ActiveX, it all works fine, however, when I talk
directly
to the CM12, it doesn't :-(

For a normal transmission, you send two bytes to the interface, and it
responds
with a checksum.

This works fine - I get the checksum back from the interface, acknowledge
it,
and the interface sends the signal.

For extended codes, you send four bytes to the interface, and it sends you
back
the checksum.
The first byte is always 00000111 (0x07).
The second byte contains the housecode in the most significant nibble, and
0111
in the least significant nibble.
The 3rd and 4th bytes are the extended data, which can be anything between
0x00
and 0xFF.

However, after having sent my 4 bytes to the CM12, I get nothing back - no
checksum at all.

Anyone got any ideas on where I'm going wrong? Or any sample source code
(any
language/platform will do) that shows sending extended codes to the CM12.

Thanks,

John