janitza UMG 804 - Page 27

27
158.7 mm
6.25”
59.2 mm
2.33”
108.54 mm
4.27”
Serial Communications
The UMG 804 supports both Modbus
TCP/IP and Modbus RTU serials
communications.
Connect the shielded 2 wire cable to
the 2-wire Modbus RS-485 network
with the serial interface jack.
Mechanically secure the RS-485 cable(s)
where they enter the electrical panel.
Connect serial cable(s) from the RS-
485 loop to the serial connector on the
UMG 804. Connect all RS-485 devices
in a daisy-chain, and properly terminate
the chain as shown on fi gure.
Follow all applicable wiring and termi-
nation connection guidelines for the
standard in use.
Note that while both the Modbus
RTU standards identify requirements
for RS-485 line polarization/bias and
termination, the value and placement
of these resistors varies for each stan-
dard. The UMG 804 does not imple-
ment any RS-485 line polarization/
bias or termination internally. For the
RS-485 cable, use shielded, twisted-
pair wire that is voltage-rated for the
installation.
Connect the shield to Earth Ground
somewhere on the RS-485 bus (single
point connection only).
RS485 cable
(two wire + GND)
120 Ω termination
resistor when required
Data
GND
Tx-
Rx-
Tx+
Rx+
G (-) (+)
Data
GND
Tx-
Rx-
Tx+
Rx+
G (-) (+)
Data
GND
Tx-
Rx-
Tx+
Rx+
G (-) (+)
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