Rs485 Cabling; Current Loop (20 Ma) Cabling; Fig. 7-7: Rs485 Cabling - 4-Port Serial Interface; Fig. 7-8: Active Transmission/Active Reception 4-Port Serial Interface - Addi-Data ADDICOM APCI-7300 Technical Description

Connecting the peripheral

RS485 cabling

Fig. 7-7: RS485 cabling - 4-port serial interface

Current loop (20 mA) cabling

Active / passive : When a transmitter and a receiver communicate, one of
them has to supply the necessary current. If the transmitter supplies the
current, it is active. The receiver is passive. In reverse, if the receiver
supplies the current, it is active.
Fig. 7-8: Active transmission/active reception
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4-port serial interface
APCI-7xxx