American Telecom AM64/128A - Manual (Page 45)

AM64/128A User Manual Appendix B – Internal Link Settings
A-6
Interface Modules
X.21 Interface Module:
J1 - X.21 T (Transmit data) Circuit Termination – This link connects a 120 ohm load resistor across the T
circuit position 1-3. This helps maintain signal rise times and minimises reflections at rates greater than 9.6
kbps over long lines. At lower rates and over short lines the termination resistor may be omitted, (link set
position 1-2).
J2 – X.21 SEXT (External Signal Element Timing) Circuit Termination – This link connects a 120 ohm load
resistor across the SEXT circuit in position 1-3. This helps maintain signal rise times and minimises
reflections at rates greater than 9.6 kbps over long lines. At lower rates and over short lines the termination
resistor may be omitted, (link set position 1-2).
V.35 Interface Module:
J1 – V35 Circuit 113 (External Signal Element Timing) Input Polarity Selection – This aspect of the V35
interface may be implemented differently by different manufacturers. This link allows the authorised
personnel to swap the polarity of the A and B wires of this differential input circuit. The factory default
setting for this position 1-2.
V.36 Interface Module:
J1 – Circuit 103 Termination.
J2 - Circuit 113 Termination.
Removable link shown joining pins 1-2,
to reverse connection of A and B wires
to Circuit 113 move link to position 1-3.
J1 – Circuit 103 Termination.
J2 – Circuit 113 Termination.