GE T35 Instruction Manual page 61

3 HARDWARE
The clock terminating impedance should match the impedance of the line.
The following figure shows the typical pin interconnection between two RS422 interfaces. All pin interconnections are to be
maintained for a connection to a multiplexer.
Figure 3–28: TYPICAL PIN INTERCONNECTION BETWEEN TWO RS422 INTERFACES
b) TWO CHANNEL APPLICATIONS VIA MULTIPLEXERS
The RS422 Interface may be used for '1 channel' or '2 channel' applications over SONET/SDH and/or Multiplexed systems.
When used in 1 channel applications, the RS422 interface links to higher order systems in a typical fashion observing Tx,
Rx, and Send Timing connections. However, when used in 2 channel applications, certain criteria have to be followed due
to the fact that there is 1 clock input for the two RS422 channels. The system will function correctly if the following connec-
tions are observed and your Data Module has a feature called Terminal Timing. Terminal Timing is a common feature to
most Synchronous Data Units that allows the module to accept timing from an external source. Using the Terminal Timing
feature, 2 channel applications can be achieved if these connections are followed: The Send Timing outputs from the Multi-
plexer - Data Module 1, will connect to the Clock inputs of the UR–RS422 interface in the usual fashion. In addition, the
Send Timing outputs of Data Module 1 will also be paralleled to the Terminal Timing inputs of Data Module 2. By using this
configuration the timing for both Data Modules and both UR–RS422 channels will be derived from a single clock source. As
a result, data sampling for both of the UR–RS422 channels will be synchronized via the Send Timing leads on Data Module
1 as shown in the following figure. If the Terminal Timing feature is not available or this type of connection is not desired, the
G.703 interface is a viable option that does not impose timing restrictions.
GE Multilin
W 3b
Tx -
W 3a
Rx -
W
2a Tx +
W 4b
Rx +
W
6a
Shld.
W 5b
Tx -
W
5a Rx -
W
4a
Tx +
W
6b Rx +
W
7b
Shld.
W 7a
+
W
8b
-
W 2b com
W
8a
Figure 3–27: RS422 INTERFACE CONFIGURATION
W 3b
Tx -
W 3a
Rx -
RS422
W 2a
Tx +
CHANNEL 1
W
Rx + 4b
W
6a
Shld.
W 7a
+
CLOCK
W
- 8b
com W 2b
+
W 8a
SURGE
64 KHz
T35 Transformer Management Relay
3.3 DIRECT I/O COMMUNICATIONS
RS422
CHANNEL 1
RS422
CHANNEL 2
CLOCK
SURGE
RS422.CDR
p/o 827831A6.CDR
W 3b
Tx -
W 3a
Rx -
RS422
W 2a
Tx +
CHANNEL 1
W
4b Rx +
W
6a
Shld.
W 7a
+
CLOCK
W
8b -
W 2b com
W 8a
SURGE
831728A3.CDR
3
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