Siemens SIMATIC ET 200SP Product Information page 59

Table 2- 9 Measured values in case of a line break in a TC measurement with enabled reference junction (reference chan-
nel) depending on enabled diagnostic information
Case Programmable diagnostics
Reference channel
Wire break
1 Enable
3
2 Disable
3
3 *
4 *
5 *
* Parameter assignment not relevant
The wire break test can only be disabled via data set 237.
1
Diagnostics is suppressed in the event of a reference channel error.
2
Channel with line break
3
Measured value taken from the reference channel
4
Explanations of the cases:
Case Reference channel
1 The "wire break" diagnostics is reported.
This has a higher priority than the "Underflow" diagnos-
tics.*
2 No diagnostics reported. A wire break check is carried
out (i.e. test current flows).*
3 Measured values are in the valid measuring range
4 Measured values are in the valid measuring range
5 Measured values are in the valid measuring range
* Channel with wire break
Product information on the documentation of the ET 200SP distributed I/O system
Product Information, 02/2021, A5E03799595-BG
TC channel
Underflow Wire break
* *
3
* *
3
* Enable
3
* Disable
3
* Disable
1.3
Supplements to ET 200SP documentation
Reference channel
Underflow
* 32767
2 3
* 32767
2 3
* Valid
3
* Valid
3
Valid
*3
TC channel
The "Reference channel error" diagnostics is reported if
this is enabled. Where own pending diagnostic infor-
mation ("overflow" or "underflow") is reported as out-
going. Wire break diagnostics is detected independently
of the measured value and has the same priority as the
"Reference channel error" diagnostics. Both items of diag-
nostic information can be pending simultaneously. The
measured value of the reference channel (RTD channel) is
adopted for the TC channel. The validity of the measured
value of the TC channel is irrelevant.
Behavior corresponds to case 1.
The "wire break" diagnostics is reported.*
No diagnostics reported. A wire break check is carried out
(i.e. test current flows).*
No "wire break" diagnostics is reported. No wire break
check is carried out (i.e. no test current flows). This is
required to calibrate thermocouples, since the test current
necessary for a wire break check leads to measurement
errors during calibration.*
2.5 I/O module manuals
Measured value
TC channel
7FFF 32767
H 3 4
7FFF 32767
H 3 4
Valid 32767
3
Valid 32767
3
Valid Undefined
7FFF
H 4
7FFF
H 4
7FFF
H 3
7FFF
H 3
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