AMG Systems Ltd. reserves the right to make changes to this
document without notice. The information herein is believed to
be accurate. No responsibility is assumed by AMG for its use.
Page 5 of 8
AMG4784E Instruction Sheet D32046-
00
Data and Audio Channel Configuration
Data and Audio Channel Configuration
The
AMG4784E
and rackmount equivalent
AMG4784ER
sends and receives data to/from Channel A.
Channel B is not available. Channel A is a single data interface selectable by the user with the slide
switch on the rear panel.
Data Interface Connections Channel A
RJ45 Pin
No.
Channel A
Cat 5/6 Cable
Colour Code T568B
RS485
[switch low]
RS422 [switch
mid]
RS232
[switch high]
1
IN + (A)
GND
White/orange
2
IN - (B)
IN
Orange
3
White/green
4
Blue
5
White/blue
6
Green
7
IN/OUT + (A)
OUT + (A)
N/A
White/brown
8
IN/OUT - (B)
OUT - (B)
OUT
Brown
Note: (A) or (B) in brackets in above table refers to RS485 / RS422 data specification, not Channel A,
Channel B.
Data Channel A Configuration
Channel A is always present and allows for a RS232, RS422 (full duplex, four wire) or RS485 (half
duplex, two wire) interface depending on the position of the switch located above the RJ45 connector.
The switch signifies the presence of the X16004 Low Speed Data/Audio Interface Board. If there are
LED's present on the RJ45 connector then an X16003 Ethernet Interface Board is fitted.
The data input for both the RS485 and the RS422 modes detects a tri-state input condition by
monitoring the differential voltage level across the input. A differential level below 600mV positive or
negative will be detected as a tri-state condition. A level above 600mV positive or negative will be
detected as a logic 1 or logic zero respectively. It is important therefore to terminate the RS485 bus or
the RS422 input bus using 120Ω if a pre-bias is present on the RS485 or RS422 bus.
A large number of third party equipment manufacturers apply a pre-bias on their RS485 bus. This pre-
bias is applied by pulling one arm of the RS485 bus high (+5 volts) and the other arm low (0 volts)
using high value resistors within the third party equipment. In order to ensure that the AMG equipment
detects a tri-state condition, then these resistors should have
a value above 5kΩ. If the third party
bias resistors are less the 750Ω the bus can be double or triple terminated as required to ensure that a
tri-state level is detected.
Note: The Data Channel A is shipped from the factory set up for RS485 operation unless otherwise
requested.