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Siemens TX-I/O™ Module system – Functions and operation CM110561en_08
Building Technologies Digital input functions 2018-10-25
Digital inputs cannot be overridden locally. The override button has no effect, and if an
attempt is made to operate it, an error is displayed.
• The LED lights up in accordance with the existing signal status
• Modules with an LCD panel display the source signal "Σ" (Counter), plus a block of 3
fields which change with each pulse:
N/O contact
I/O status LED
LCD display
ON
OFF
closed
open
10561D106
100 ms100 ms100 ms
N/O
Diagram: Cause and effect
The LEDs and LCD icons take at least 100 ms to change their state, even if the signals
have a higher frequency.
For details, especially in relation to flashing pattern and errors: refer to the section
"Display, operation and diagnostics" in the TX-I/O™ Engineering and installation guide
[6].
• In the event of a communication failure the counter function is maintained.
The counter values
– continue to be accumulated
– are indicated by LED
– periodically buffered
– only if Power Up = Last Value
– immediately after communication failure, and then each 15 min for max. 3 days
(the number of write actions on the FLASH memory are limited).
• In the case of lacking module supply, the behavior depends on the configuration
value Power Up
– Reset: upon the next start-up, the counter is reset to 0
– Last Value: upon the next start-up, the counter is reset to the last value of the
buffer; some pulses may be lost.
• When communication is restored, the bus master polls the counter reading again.
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