3-30 B30 Bus Differential System GE Multilin3.3 DIRECT INPUT AND OUTPUT COMMUNICATIONS 3 HARDWARE3.3.4 G.703 INTERFACEa) DESCRIPTIONThe following figure shows the 64K ITU G.703 co-directional interface configuration.The G.703 module is fixed at 64 kbps. The SETTINGS > PRODUCT SETUP > DIRECT I/O > DIRECT I/O DATARATE setting is not applicable to this module.AWG 24 twisted shielded pair is recommended for external connections, with the shield grounded only at one end. Con-necting the shield to pin X1a or X6a grounds the shield since these pins are internally connected to ground. Thus, if pin X1aor X6a is used, do not ground at the other end. This interface module is protected by surge suppression devices.Figure 3–32: G.703 INTERFACE CONFIGURATIONThe following figure shows the typical pin interconnection between two G.703 interfaces. For the actual physical arrange-ment of these pins, see the Rear terminal assignments section earlier in this chapter. All pin interconnections are to bemaintained for a connection to a multiplexer.Figure 3–33: TYPICAL PIN INTERCONNECTION BETWEEN TWO G.703 INTERFACESPin nomenclature can differ from one manufacturer to another. Therefore, it is not uncommon to see pinouts num-bered TxA, TxB, RxA and RxB. In such cases, it can be assumed that “A” is equivalent to “+” and “B” is equivalentto “–”.b) G.703 SELECTION SWITCH PROCEDURES1. With the power to the relay off, remove the G.703 module (7R or 7S) as follows. Record the original location of themodule to help ensure that the same or replacement module is inserted into the correct slot.2. Simultaneously pull the ejector/inserter clips located at the top and at the bottom of each module in order to release themodule for removal.3. Remove the module cover screw.4. Remove the top cover by sliding it towards the rear and then lift it upwards.5. Set the timing selection switches (channel 1, channel 2) to the desired timing modes.6. Replace the top cover and the cover screw.NOTENOTE
