Aidcall Touchsafe Pro Installation Manual page 8

7. SITE WIRING REQUIREMENTS
RS485 BUS
It is important that the RS485 data bus wiring network is connected in one continuous "daisy-chain" from
the Interface through the Master and all Slave Bases installed on the scheme...
Nursecall
Panel
PSU
Note: the first and the last units (this could be any type depending on site layout) connected on the RS485
bus must have an end of line (EOL) Jumper fitted – see section 10 for details.
IMPORTANT: the RS485 data bus must not be split into multiple legs from a mid-point in the wiring and
small groups of devices should not be spurred off at any point in the network...
Nursecall
Panel
PSU
POWER BUS
On large installations with multiple Slave Bases and/or a bus cable length exceeding 100 metres it will be
necessary to fit additional PSU's at remote points in the building...
Nursecall
Panel
PSU
1
If the voltage on a Slave Base gets down to 8V DC then an additional PSU will be required for any units
connected beyond this point.
Master
Base
Interface
RS485 devices are wired in a daisy-chain formation
(Max cable length: 600 metres for data)
Master
Base
Interface
Master
Base
12V
Interface
12V
Do not common the 12V line between multiple PSU's.
Slave Slave
Base Base
Slave
Base

Slave
Base
Slave
Slave
Base
Base
10V 8V
PSU
2
Last Slave
Base
✓
Slave
Base

Slave
Base
INCORRECT – do not spur
off or split the network into
multiple legs
Slave Slave
Base
Base
12V 10V
Doc No. FM5600 issue E Page 8