Siemens TX-I/O TXM1.8D Functions And Operation page 16

Local override
Display
N/O contact
Acknowledgement
(P-bus)
Process value
(P-bus)
I/O status LED
LCD display
Response in the
event of a fault
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Siemens
Building Technologies
I/O Module
I/O status LED
N/O Contact
Signal Processing
(D20S)
Block diagram of function
• The signal is read and debounced (pulses longer than 20 ms)
• The pulse is then saved in the P-bus BIM and transmitted to the automation station
• The automation station acknowledges receipt (Acknowledge)
• The memory is cleared, and the input is ready for a new pulse
Additional incoming pulses before the Acknowledge are ignored.
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 I/O status LED shows the source signal
• The LCD panel (if available) shows the source signal type (status contact, N/O)
and the activity of the contact
• However, for quickly changing signals, a maximum changing frequency of 5 Hz is
maintained by the displays.
N/O
Diagram: Cause and effect
For details, especially in relation to flashing pattern and errors: refer to the section
"Display, operation and diagnostics" the TX-I/O™ Engineering and installation guide [6].
In the event of an interruption in communication with the automation station, the last
unpolled pulse is stored in the module. and the incoming pulses on the module
continue to be displayed..
TX-I/O™ Module system – Functions and operation
Digital input functions
P-Bus BIM
LCD
Island
Bus
Process
Memory
value
Acknowledge
P-Bus
Process
value
P-Bus
closed
open
active
inactive
ON
OFF
10561D105
CM110561en_08
2018-10-25