GE Multilin D60 Line Distance Relay 3-293 HARDWARE 3.3 DIRECT INPUT/OUTPUT COMMUNICATIONS3d) RECEIVE TIMINGThe 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 DPLL (Digital Phase Lock Loop) circuit is utilized. The DPLL isdriven by an internal clock, which is over-sampled 16X, and uses this clock along with the data-stream to generate a dataclock that can be used as the SCC (Serial Communication Controller) receive clock.3.3.6 RS422 AND FIBER INTERFACEThe following figure shows the combined RS422 plus Fiber interface configuration at 64K baud. The 7L, 7M, 7N, 7P, and 74modules are used in 2-terminal with a redundant channel or 3-terminal configurations where Channel 1 is employed via theRS422 interface (possibly with a multiplexer) and Channel 2 via direct fiber.AWG 24 twisted shielded pair is recommended for external RS422 connections and the shield should be grounded only atone end. For the direct fiber channel, power budget issues should be addressed properly.When using a LASER Interface, attenuators may be necessary to ensure that you do not exceed MaximumOptical Input Power to the receiver.Figure 3–35: RS422 AND FIBER INTERFACE CONNECTIONConnections shown above are for multiplexers configured as DCE (Data Communications Equipment) units.3.3.7 G.703 AND FIBER INTERFACEThe figure below shows the combined G.703 plus Fiber interface configuration at 64K baud. The 7E, 7F, 7G, 7Q, and 75modules are used in configurations where Channel 1 is employed via the G.703 interface (possibly with a multiplexer) andChannel 2 via direct fiber. AWG 24 twisted shielded pair is recommended for external G.703 connections connecting theshield to Pin 1A at one end only. For the direct fiber channel, power budget issues should be addressed properly. See pre-vious sections for more details on the G.703 and Fiber interfaces.When using a LASER Interface, attenuators may be necessary to ensure that you do not exceed MaximumOptical Input Power to the receiver.Figure 3–36: G.703 AND FIBER INTERFACE CONNECTIONWARNINGL907LNMP.CDRP/O 827831AE.DWGWARNINGW7E, F, G and QTx2Rx2FIBERCHANNEL 2XXXXXXRx +Shld.Tx -Rx -Tx +2b1b1a3a2a3bG.703CHANNEL 1SURGE
