User manual

Appendix E 97
Eight-Wire Synchronous Modem Wiring
Eight-Wire Synchronous Modem wiring allows T1 Modem Bank units to be installed in remote locations and
connected to the EPC/X host adapter via RS-232 or RS-422 synchronous modems.
The EPC/X host adapter and the T1 Modem Bank have been designed so that the synchronous ports can support
either RS-422 or RS-232 line levels. To connect EPC/X host adapters and T1 Modem Banks to RS-232 synchronous
modems, use the special cables shown in Figure 35.
Note that only the negative lead for each RS-422 signal is used in this configuration. The positive lead is left
“floating”.
If you are building your own cable, four 2200 pF capacitors (X7R 50V type) are required—two for the EPC/X host
adapter and two for the T1 Modem Bank. Install the capacitors between the positive and negative leads of the TxC
and RxC signals on the back of the HD-15 connectors, as shown in Figure 35.
Figure 35 RS-232 Synchronous Modem Cables