GE C70 Instruction Manual page 80

DIRECT INPUT AND OUTPUT COMMUNICATIONS CHAPTER 3: INSTALLATION
Figure 3-28: Direct input and output single-channel connection
3
IRC modules with protocol C37.94 and G.703 are designed for back-to-back communication connections, so the ring
configuration shown in the previous figure does not apply. To establish inter-relay communication in more than two URs,
you need to have two channel IRC module and enable DIRECT I/O CHANNEL CROSSOVER function in all relays, as shown in
the next figure. This configuration can be expanded to 16 URs, and this configuration does not provide redundancy ring
since both channels are made into single ring by the channel crossover function. As per the figure Typical Pin
Interconnection between Two G.703 Interfaces later in this chapter, the clock is supplied typically by multiplexer (MUX) and
all URs are in Loop Timing Mode. If there is no MUX, then UR1 and UR3 can be in Internal Timing Mode and UR2 and UR4
can be in Loop Timing Mode. That is, connected channels must have opposite timing modes.
Figure 3-29: Ring configuration for C37.94 module (concept also applies to G.703)
The interconnection for dual-channel type 7 communications modules is shown as follows. Two-channel modules allow for
a redundant ring configuration. That is, two rings can be created to provide an additional independent data path. The
required connections are: UR1-Tx1 to UR2-Rx1, UR2-Tx1 to UR3-Rx1, UR3-Tx1 to UR4-Rx1, and UR4-Tx1 to UR1-Rx1 for the
first ring; and UR1-Tx2 to UR4-Rx2, UR4-Tx2 to UR3-Rx2, UR3-Tx2 to UR2-Rx2, and UR2-Tx2 to UR1-Rx2 for the second ring.
3-32 C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL