User's Manual

TD 93021US Rev A
10 FEB 2014 / Ver A 9
Installation Guide
teleCARE IP
• The resistance of the wires in the room bus cable increases with the length and this causes the
voltage to decrease progressively along the length of the cable.
• The room bus voltage also drops in proportion to the load.
• The effect of “cross-talk” increases as the cable length increases.
Room Bus Power Considerations
The room bus power supply output from the room controller is limited to 300mA per room
bus but the maximum acceptable load on the room bus decreases significantly as the
distance from the room controller increases due to the resistance of the room bus cable.
Room Bus Voltage Considerations
The power supply to the room bus at the output from the room controller is >5.5Vdc without load but
this will drop as the room bus cable length and/or the load increases. The minimum acceptable voltage
at any point on the room bus cable is 4.5Vdc.
Room Bus Cable Length and Power Limitations
The IP Room Controller offers up to three room buses. The load of any room bus must not exceed
300mA and the minimum acceptable voltage anywhere along the room bus is 4.5 volts.
When UTP category 5 cable (or higher) is used the length of any room bus cable should not exceed
98.4ft (30m), irrespective of the load. Below 98.4ft (30m), the maximum acceptable length of the
room bus cable depends on the load (including third-party devices).