B&B Electronics Zlinx 485 - Manual (Page 12)

Hardware
Manual Documentation Number: Zlinx485m-1808
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Figure 8. Zlinx 485 Base Module RS-422/485 Connector
RS-422/485 Four-Wire Mode
When the Zlinx Base module is configured to operate in RS-422/485 four-wire mode the
receive terminals are connected to the transmit terminals of the Modbus device it is
communicating with. Its transmit terminals are connected to the receive terminals of the
Modbus device it is communicating with.
Figure 9. RS-422/485 Four-Wire Connection
RS-422/485 Two-Wire Mode
When the Zlinx Base module is configured to operate in RS-485 two-wire mode (RS-
422/485 switch in the right position) the two-wire RS-485 two-wire communications
cable pair is connected to Terminals TDB and TDA. The communications cable
ground/shield is connected to GND.