homevision digital thermostat problems

[Steven Edgar <yahoogroups@xxxxxxx>]

I've recently purchased a homevision unit with the port expander module.
The 
first thing I've tried to do with it is wire it up to a load of digital
thermometers (1-wire Maxim devices).

On my first go I got the whole thing working fine, it was reading the 
temperatures ok, but I ran into a problem when I hit 4 sensors (I'm doing
each room individually). I traced that down to capacitance and possibly
reflection issues, so followed the guidelines on the homevision website to
cut that down. Now however nothing works, even when I connect just one
sensor 
directly to the module using a short piece of wire (few inches) using no
extra components or connections. I've buzzed everything through, nothing is
open or shorted, all the connections to the chip are fine. I've tried
several 
(unused) chips with the same results. The other mods for the length
problems 
are disconnected from Homevision, and were also checked for continuity
before 
they were first connected. 

I've tried connecting to one of the other ports compatible with the temp
sensors, but none seem to work either.

I've loaded a blank schedule into homevision (with just the expansion board
setting on), just the configure digital temperature screen still can't find
any device on the network.

I can only conclude that the expansion board has failed, but thought I'd
ask 
for advice from here before returning it to the vendor. Anyone think of
something I've missed?


Thanks

Steven



http://www.automatedhome.co.uk
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