Line Break Monitoring; Digital Outputs And Comparator Channel; Digital Outputs; Comparator Channel - Siemens SIMATIC S5 Manual

Operation
A mixture of current and voltage inputs is only feasible with an ADC sensitivity of 512 mV.
Modifying the Pt 100 input (channel 15)
By removing the jumpers X8/9-X9/9 and X8/10-X9/10, the Pt 100 input can be converted to a
voltage or current input. The calculation of R
(see also Section 3.4).
3.1.7 Line Break Monitoring / Wire Break Monitoring
When using thermocouples, analog inputs 0 to 12 and 15 are monitored for line breaks.
This is achieved by briefly applying a test current to the measurement loop.
Depending on the parameter assignment, an emergency program can then be activated to
switch to a substitute thermocouple or substitute Pt 100 or a sensor.
When switching off the characteristics linearization the line break monitoring is switched off
automatically.

3.2 Digital Outputs and Comparator Channel

3.2.1 Digital Outputs

17 outputs protected against interference voltage and short-circuit proof are available for the
output of manipulated variables. The status of the output stages is displayed by LEDs on the
front panel (for the assignment of socket connector X4: see Section 2.2.2).
When the 5 V voltage is supplied, the controller outputs respond briefly once. Owing to the slow
reactions of the heating circuits or contactors, the flickering of the indicators is tolerable.
If one or more output stages are operating with a short circuit, a red group short circuit display
(LED) on the front panel lights up (see Fig. 1.2/1).

3.2.2 Comparator Channel

To allow limit value monitoring, a comparator channel is connected to digital output DQ 18 (K) in
parallel with the analog input channel 13.
The signal present at analog input 13 is amplified by a differential amplifier and compared by a
comparator with the signal set as the limit value by the microprocessor via a digital-to-analog
converter.
If the input voltage of channel 13 exceeds the limit value set by the microprocessor (resolution
of 10 bits) digital output DQ 18 (K) is energized.
2–26
(R226) and R (R227) is as described above
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IP244
C79000–B8576–C859–02