User`s manual

Installation
20 User’s Manual - DSP19.2 Fast Poll Modem
Table 2-4. Transmission Line Connector Pin Assignments
This Pin Number… Corresponds to This Signal…
1 Rx
2 Rx
3 Tx (Tx/Rx)
4 Tx (Tx/Rx)
5 Earth Ground (optional)
NOTE:
When 2-wire half duplex is used, the TX pair must be used for both transmit
and receive.
Figure 2-6. DSP19.2 Modem Transmission Line Interface