3.3 DIRECT INPUT AND OUTPUT COMMUNICATIONS
The following figure shows the 64K ITU G.703 co-directional interface configuration.
The G.703 module is fixed at 64 kbps. The SETTINGS ð PRODUCT SETUP ðò DIRECT I/O ðò DIRECT I/O DATA
RATE 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 X1a
or X6a is used to ground the shield at one end, do not ground the shield at the other end. This interface module is protected
by surge suppression devices.
The 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 be
maintained for a connection to a multiplexer.
Figure 3–33: TYPICAL PIN INTERCONNECTION BETWEEN TWO G.703 INTERFACES
Pin nomenclature may 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 equivalent
b) G.703 SELECTION SWITCH PROCEDURES
With the power to the relay off, remove the G.703 module (7R or 7S). The ejector/inserter clips located at the top and at
the bottom of each module, must be pulled simultaneously in order to release the module for removal. The original
location of the module should be recorded to help ensure that the same or replacement module is inserted into the cor-
Remove the module cover screw.
Remove the top cover by sliding it towards the rear and then lift it upwards.
Set the timing selection switches (channel 1, channel 2) to the desired timing modes.
Replace the top cover and the cover screw.
Figure 3–32: G.703 INTERFACE CONFIGURATION
L60 Line Phase Comparison System
3.3.4 G.703 INTERFACE