RMG ERZ2000-NG, Operating Manual

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6 Flow meters
Manual ERZ 2000-NG · EN07 · 2019, May 13th
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6.4.2 Modbus communication with the USM GT400
The Modbus communication between ERZ2000-NG and ultrasonic meters is de-
scribed as generally as possible, wherein the USM GT400 was chosen as a concrete
example (Figure 1). The Modbus registers of Instance F are listed in column BA in
the USM GT400.
6.4.3 Electrical connection
Figure 162: Connection of the Modbus interface of the USM to COM 6
shows the
rear wall of the ERZ2000-NG. The USM GT400 is connected to serial interface
COM6.
Figure 162: Connection of the Modbus interface of the USM to COM 6
6.4.4 USM GT400 connection area
There are three serial interfaces available for Modbus communication on the USM
GT400 ultrasonic meter (and USZ 08). The RS 485-2 with terminal 21 (GND) , termi-
nal 22 (Data +) and terminal 23 (Data -) is provided for the Instance F Modbus com-
munication; based on the parameterizable byte sequence, it is suitable for the manu-
facturer-independent Instance F protocol. The other interfaces can be used without
any further settings. The
RS 485-0 with terminal 15 ( GND ), terminal 16 ( Data + ) and
terminal 17 ( Data - ) is reserved for the operating and service software RMGView USM .
The RS 485-1 with terminal 18 ( GND ), terminal 19 ( Data + ) and terminal 20 ( Data - )
should (preferably) be used for the RMG standard of the digital totalizer status trans-
mission "DZU".