Installation guide

VAR4 / VAR12 / VAR20 - Product Description
3.9 Remote I/O Units
The VAR Router is able to support the connection of up to 9 Remote I/O units (ASL Product: BMB01).
The BMB01 units provide additional analogue and opto-isolated digital inputs, and open collector digital
outputs. This extends the control and interfacing capability of the system. The BMB01 units are interfaced via
a power and RS485 data link that can be up to 1 km long, in order to interface to remote equipment.
Each BMB01 Remote I/O Unit provides the I/O capability as described in Table 5.
Table 5 Remote I/O Unit Inputs and Outputs
Type Quantity Functions
Analogue Input non-isolated 12 Programme Selector
Volume Control
Ambient Noise Sensor (ANS)
Fault Input
Digital Input opto-isolated 12 Routing Control
Reset Input
Fault Input
Digital Output open-collector 12 Busy Output
The VAR4 provides a single RS485 bus for the connection of the Remote I/O Units. The VAR12 and 20
provide 2 and 3 such busses respectively. These are labelled EXP on the rear panels. See the examples
shown in Figure 9.
Up to 9 Remote I/O Units may be connected in total each with a unique address set up using an internal
rotary switch. The Remote I/O Units can be connected to any of the RS485 busses.
If using a VAR12 or VAR20, in order to optimise response time, it is sensible to distribute them across the
alternative busses.
Figure 9 Remote I/O Connection to RS485 Busses
RS485
RS485-3
RS485-2
RS485-1
7 8 9
4 5 6
1 2 3
2 31
Example using VAR4:
Example using VAR20:
= 120 ohm
TERMINATION FITTED
Issue: 03 complete, approved
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