ROC364 Instruction Manual
4-14 Communications
Cards
Rev
Jun/05
4.4.2 EIA-422/485 (RS-422 / 485) Communications Card Wiring
Figure 4-11 shows the signals and pin numbers for the communications port 9-pin connector. Wiring
should be twisted pair cable, one pair for transmitting and one pair for receiving. Jumper P4 controls the
RTS transmit functions in the EIA-422 (RS-422) mode. Jumper P4 has a default setting of RTS for
multi-drop communications. Placing jumper P4 in the ON position enables the card to continuously
transmit (point-to-point).
Figure 4-12 shows the relationship between the EIA-485 (RS-485) signals and pin numbers for the
communications port 9-pin connector. Wiring should be twisted-pair cable.
Figure 4-11. EIA-422 (RS-422) Wiring Schematic
Figure 4-12. EIA-485 (RS-485) Wiring Schematic