GE Multilin B90 Low Impedance Bus Differential System 3-273 HARDWARE 3.3 DIRECT INPUT/OUTPUT COMMUNICATIONS33.3DIRECT INPUT/OUTPUT COMMUNICATIONS 3.3.1 DESCRIPTIONThe B90 direct inputs and outputs feature makes use of the type 7 series of communications modules. These modules arealso used by the L90 Line Differential Relay for inter-relay communications. The direct input and output feature uses thecommunications channels provided by these modules to exchange digital state information between relays. This feature isavailable on all UR-series relay models except for the L90 Line Differential relay.The communications channels are normally connected in a ring configuration as shown below. The transmitter of one mod-ule is connected to the receiver of the next module. The transmitter of this second module is then connected to the receiverof the next module in the ring. This is continued to form a communications ring. The figure below illustrates a ring of fourUR-series relays with the following connections: UR1-Tx to UR2-Rx, UR2-Tx to UR3-Rx, UR3-Tx to UR4-Rx, and UR4-Txto UR1-Rx. A maximum of sixteen (16) UR-series relays can be connected in a single ringFigure 3–26: DIRECT INPUT AND OUTPUT SINGLE CHANNEL CONNECTIONThe interconnection for dual-channel Type 7 communications modules is shown below. Two channel modules allow for aredundant ring configuration. That is, two rings can be created to provide an additional independent data path. The requiredconnections are: UR1-Tx1 to UR2-Rx1, UR2-Tx1 to UR3-Rx1, UR3-Tx1 to UR4-Rx1, and UR4-Tx1 to UR1-Rx1 for the firstring; and UR1-Tx2 to UR4-Rx2, UR4-Tx2 to UR3-Rx2, UR3-Tx2 to UR2-Rx2, and UR2-Tx2 to UR1-Rx2 for the secondring.Figure 3–27: DIRECT INPUT AND OUTPUT DUAL CHANNEL CONNECTIONThe following diagram shows the connection for three UR-series relays using two independent communication channels.UR1 and UR3 have single type 7 communication modules; UR2 has a dual-channel module. The two communication chan-nels can be of different types, depending on the Type 7 modules used. To allow the direct input and output data to cross-over from channel 1 to channel 2 on UR2, the DIRECT I/O CHANNEL CROSSOVER setting should be “Enabled” on UR2. Thisforces UR2 to forward messages received on Rx1 out Tx2, and messages received on Rx2 out Tx1.842006A1.CDRTxTxTxTxUR #1UR #2UR #3UR #4RxRxRxRx842007A1.CDRTx1UR #1UR #2UR #3UR #4Tx1Tx1Tx1Tx2Tx2Tx2Tx2Rx1Rx1Rx1Rx1Rx2Rx2Rx2Rx2
