Specifications

Audio International, Inc. A/V-9691-01(-02)-x Installation & Operation Manual
Document # 540250, Rev D, 07/2004
Page 16 of 33
3.6.2 RS-485 Data bus Characteristics
The Audio/Video Distribution Unit is designed to interface with other
AI equipment via AI’s proprietary RS-485 digital data bus. This is a
bi-directional data bus that allows multiple units to be connected
simultaneously. All RS-485 data bus lines must be daisy-chained
between units. Maximum allowable number of data bus nodes per
data bus segment is 32 nodes.
A/V-9691-01(-02)-x module accounts for six (6) data bus nodes.
If more data bus nodes are required, then an RS-485 data bus
repeater must be used to prevent loading of the data bus. The
AI-485RP-10-x provides for data bus buffering to allow multiple
data bus segments to be present within the same data bus system.
Furthermore, the AI-485RP-10-x provides for added data bus
integrity in the unlikely event a data bus failure may occur on one
segment or another by providing a data bus-shedding feature.
Should a data bus failure or lock-up occur on any given data bus
segment, the AI-485RP-10-x will shed the failing segment to
prevent total failure of the data bus system.
It is necessary to provide an access port to allow for configuration
control and setup of the unit. This connection simply requires a
9-pin connector with +28 VDC, ground, Data Bus A (HI), Data Bus
B (LO), and Data Bus Shield connections. This connection will
allow for interface of the MSM2912-01-x module to be used during
configuration of the system. The MSM2912-01-x module is an
RS-232 / RS-485 converter that needs to be purchased along with
any system that uses the A/V-9691-01(-02)-x module. The
MSM2912-01-x pinout is as follows:
P1 (RS-232) P2 (RS-485)
Pin # Description Pin # Description
1 Reserved 1 +28 VDC Power Input
2 Receive Data 2 Ground
3 Transmit Data 3 Data Bus A (HI)
4 Reserved 4 Data Bus B (LO)
5 Signal Ground 5 Data Bus Shield
6 Reserved 6 Reserved
7 Reserved 7 Reserved
8 Reserved 8 Reserved
9 Reserved 9 Reserved