
EK280
Application Manual
111
7.4.3
RS485 interface, electrically isolated
7.4.3.1 Wiring
i
When the EK280 is connected to a RS485 bus there must be no terminal resistors connected to
the bus!
Due to the current limit for intrinsically-safe apparatus approval, the EK280 cannot supply sufficient current to
power terminal resistors. At the data transfer rate used, terminal resistors are not required.
7.4.3.1.1 Two-wire simplex - wiring
i
This function is only available since EK280 software version 2.20.
EK280
Bus Master
RS485
T-
Data -
T+
Data +
R-
R+
Power supply
RS-485 (5...8 V DC)
Ri
+
GND
-
Uext+
Uext-
Power supply
EK280 (8 V DC)
+
-
Further
Bus participants
Data -
Data +
7.4.3.1.2 Four-wire full duplex - wiring
EK280
R-
Bus Master
RS485
T-
R+
T+
T-
R-
T+
R+
Power supply
RS-485 (5...8 V DC)
Ri
+
GND
-
Uext+
Uext-
Power supply EK280
8V (DC)
+
-
T-
Further
Bus participants
T+
R-
R+
Содержание EK280
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