Rs422 Interface - GE D60 Instruction Manual

3.3 DIRECT INPUT/OUTPUT COMMUNICATIONS
a) DESCRIPTION
The following figure shows the RS422 2-terminal interface configuration at 64 kbps. AWG 24 twisted shielded pair is recom-
mended for external connections. This interface module is protected by surge suppression devices which optically isolated.
The RS422 module is fixed at 64 kbps only. The
setting is not applicable to this module.
RATE
NOTE
SHIELD TERMINATION
The shield pins (6a and 7b) are internally connected to the ground pin (8a). Proper shield termination is as follows:
Site 1: Terminate shield to pins 6a and/or 7b; Site 2: Terminate shield to 'COM' pin 2b.
3
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 3–30: 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
3-26
SETTINGS
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 3–29: RS422 INTERFACE CONFIGURATION
W 3b
Tx -
W 3a
Rx -
RS422
W
Tx + 2a
CHANNEL 1
W 4b
Rx +
W 6a
Shld.
W 7a
+
CLOCK
W 8b
-
W
com 2b
+
W 8a
SURGE
64 KHz
D60 Line Distance Relay
! !"
PRODUCT SETUP
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 HARDWARE

3.3.5 RS422 INTERFACE

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DIRECT I/O DIRECT I/O DATA
GE Multilin