Maximum wiring distance between SEM and Ultra Main Panel

[domotiks]

Hello.

We use screened Twisted Pair (FTP Cat.5E) cable to interconnect SEMs and some UCMs, wich are installed in different places at home, to the Ultra Main Control Panel.

We have all this distributed modules wired directly from the placewhere  they are installed to the Control Panel, and the KA-KB (Bus) and COM-12V (power) connections have been made using a star configuration.

This is the qüestion: How many length can have, as maximum,  this FTP cables? Is there any length limit on the bus wiring? And the power wiring?

Thanks a lot.

Regards. 

[ident]

First if you have SEMs, they should have their own power supply and backup battery
Only the KA/KB should be connected to Comfort, without the Common wire or the 12V wires. KA/KB which is RS485 can run a long distance when using CAT5 cables, up to 1 KM (The RS485 standard specifies 4 Km but this is with proper terminations and cable impedance)

For UCMs to Comfort, there are KA/KB and !2V/COM wires.
The 12V/COM depends on the amount of current to the UCM A UCM typically takes not more than 50 mA unless there are other loads connected to it. As long as the cable impedance is less than 50 ohms for 12V and COM. CAT5 has a resistance of 17 ohms per 100 meters so 300 meters should be OK

[domotiks]

Thanks a lot for your quick answer.

We are using SEM02 (without power module), powered by the main panel power supply. There aren\'t sensors or detectors powered by the Cytech power supply. So, that\'s the reason why we are powering SEM02 with main panel power supply.

Also, we use the entire pair on each conector (orange/white-orange for 12V; brown/white-brown for GND; blue/white-blue for KA and green/white-green for KB), so the impedance should be less than 17Ohm/100m.

We\'ll take your 300m reference in alll our projects.

Regards.