Siemens SIMATIC ET 200C, Manual

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4-46
ET 200C Distributed I/O Station
EWA 4NEB 812 6119-02b
4.4.2 Setting the Measurement Type for Analog Module ET 200C;
AI 4/8
12 Bit
The lower printed-circuit board in the analog module ET 200C;
AI 4/8
12 Bit accommodates the following module-specific DIL switch
blocks:
Table 4-19 Module-Specific DIL Switch Blocks in ET 200C; AI 4/8 12 Bit
DIL switch block Function Default setting
(as delivered)
S2 Select 2-wire or 4-wire con-
nection for Pt 100 resistance
thermometers
OFF
4-wire connection for
Pt 100
S3 Select external/internal and
floating/non-floating com-
pensation for thermocouples
ON
internal and non-floa-
ting compensation for
thermocouples
S4 Select floating or non-floa-
ting measurement
OFF
floating measurement
The rules for setting the measurement type for the analog module ET 200C;
AI 4/8
12 Bit by means of the DIL switches are as follows:
High-precision measurement with Pt 100 resistance thermometers is
ensured only if you use 4-wire connection.
The usual setting for thermocouple measurements is internal with
non-floating compensation. Use external compensation only if the
reference point has to be outside the analog module ET 200C;
AI 4/8
12 Bit. Spurious voltages can occur, caused for example by
crosstalk at the compensator input.
Non-floating compensation prevents voltage shift in the event of a
common-mode disruption at the compensator.
You should always use non-floating measurement by preference, as this
will suppress the effect of severe common-mode disruptions, for example.
When you close the module, make sure that the cover is correctly seated
as damage may occur if the cover is not aligned with the casing.
Basic Requirement
Rules
Mechanical and Electrical Installation