janitza UMG 804, User Manual And Technical Data

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14.1 Acceptable wiring configurations
The monitor may be connected to any wiring configuration shown in figure xx except for corner grounded
delta circuits.
3-wire (ungrounded)
Delta
Corner-grounded
Delta - NOT ALLOWED
4-Wire Wye 3-Wire
Phase-Phase
2-Wire
Phase-Phase
120/240V
High-Leg Delta
L3 L3
L3
L3
X
L1 L2 L1
L2 L1
L2
L1
L2
L1
N
N
N
N
2-Wire
Single-Phase
L1
N
L2 L1
15. Serial Communications
The Core Module 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 Core Module. Connect
all RS-485 devices in a daisy-chain, and properly
terminate the chain as shown on figure.
Follow all applicable wiring and termination con-
nection 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 standard. The
Core Module does not implement 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. The shield is
not internally connected to Earth Ground. Connect
the shield to Earth Ground somewhere on the RS-
485 bus (single point connection only).
RS485 cable
(two wire + shield)
120 Ω termination
resistor when required
CABLE
SHIELD
Tx-
Rx-
Tx+
Rx+
S (-) (+)
CABLE
SHIELD
Tx-
Rx-
Tx+
Rx+
S (-) (+)
CABLE
SHIELD
Tx-
Rx-
Tx+
Rx+
S (-) (+)
Fig. 25: Serial communications wiring