Two-Channel Two-Clock Rs422 Interface; Rs422 And Fiber Interface - GE N60 Instruction Manual

DIRECT INPUT AND OUTPUT COMMUNICATIONS CHAPTER 3: INSTALLATION
Figure 3-36: Clock and data transitions
Tx Clock
Tx Data
3
831733A1.CDR
3.4.5.4 Receive timing
The RS422 interface utilizes NRZI-MARK modulation code and therefore does not rely on an Rx clock to recapture data.
NRZI-MARK is an edge-type, invertible, self-clocking code.
To recover the Rx clock from the data-stream, an integrated digital phase lock loop (DPLL) circuit is utilized. The DPLL is
driven by an internal clock, which is 16-times over-sampled, and uses this clock along with the data-stream to generate a
data clock that can be used as the serial communication controller (SCC) receive clock.

3.4.6 Two-channel two-clock RS422 interface

The two-channel two-clock RS422 interface (module 7V) is for use with the synchrophasor feature. The figure shows the
module connections.
Figure 3-37: Two-channel two-clock RS422 interface connections

3.4.7 RS422 and fiber interface

The following figure shows the combined RS422 plus fiberoptic interface configuration at 64 K baud. The 7L, 7M, 7N, 7P,
and 74 modules are used in two-terminal with a redundant channel or three-terminal configurations where channel 1 is
employed via the RS422 interface (possibly with a multiplexer) and channel 2 via direct fiber.
AWG 20-24 twisted shielded pair is recommended for external RS422 connections and ground the shield only at one end.
For the direct fiber channel, address power budget issues properly.
3-30 N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL