General Electrical Information; Usm Ii Connections; Rs-485 Termination; Rs-485 Cabling - Siemens SITRANS F M MAGFLO series Operating Manual

Modbus RTU RS-485
3.2 General electrical
information
3.3

USM II connections

3.4

RS-485 termination

3.4.1 RS-485 cabling

3. Installation
On the electrical termination boards for USM II transmitters, additional input/output terminals have
been reserved for add-on module functions. The numbering range of these terminals is as follows,
but how many are actually used depends on the type of add-on module. Please refer to the
relevant handbook for other electrical connection information.
Terminals reserved for add-on modules:
MAG 6000: 91 - 97
MASS 6000: 91 - 100
Note
The standard inputs and outputs continue to function and are not affected by the presence of an
add-on module. It is however not possible to install this module in a MASS 6000 with extra outputs.
If a Current Out 2 is present, the MASS 6000 has extra outputs installed.
The following table shows the connection layout for the USM II Modbus RTU module:
Terminal number
91
92
93
94
PE
All RS-485 based networks must be terminated correct to function properly. A termination must
be placed at each end of the segment.
The Modbus RTU module can add a termination by connecting terminals 91 to 92 and 93 to 94.
It is important to use very short wires for this connection.
To ensure error free operation, a good quality cable meeting the RS-485 specifications, must be
used.
SFIDK.PS.023.D2.02
Modbus RTU RS-485 connection
T1
Data +
Data −
T2
Shield
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