GE D90 Plus Instruction Manual page 66

WIRING
G.703 communication interface
NOTE:
RS422 communication interface
56
AWG 24 twisted shielded pair is recommended for external connections, with the shield
grounded only at one end. Connecting the shield to pin B1a or B8a grounds the shield since
these pins are internally connected to ground. Thus, if pin B1a or B8a is used to ground the
shield at one end, do not ground the shield at the other end. The G.703 module chassis is
protected by surge suppression devices.
The following figure shows the 64 kbps ITU G.703 co-directional interface configuration.
Figure 31: G.703 module connections
The G.703 octet timing and timing mode are set using the
The following figure shows the typical pin interconnection between two G.703 interfaces.
All pin interconnections are to be maintained for a connection to a multiplexer.
Figure 32: Typical pin interconnection between two G.703 interfaces
Pin nomenclature differs from one manufacturer to another. It is not uncommon to see
pinouts numbered TxA, TxB, RxA, and RxB. In such cases, assume that "A" is equivalent to
"+" and "B" is equivalent to "–."
The RS422 inter-relay communications module is a dual-channel dual-clock RS422
interface. The module can be configured to run at 64 or 128 kbps. AWG 24 twisted shielded
pair cable is recommended for external connections. The module is protected by an
optically-isolated surge suppression device.
The two-channel two-clock RS422 interface is intended for use with two independent
channel banks with two independent clocks. It is intended for situations where a single
clock for both channels is not acceptable.
The shield pins (B1a and B8a) are connected internally to chassis ground. Proper shield
termination is as follows:
• Site 1 — Terminate shield to pin B1a
• Site 2 — Connect COM pin B1b to site 1 COM pin B1b. Note that pins B1b and B8b are
connected internally.
Match the clock terminating impedance with the impedance of the line.
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 3: INSTALLATION
setting.
Protocol Encoding