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Siemens
TX-I/O™ Module system – Functions and operation
CM110561en_08
Building Technologies
Digital input functions
2018-10-25
•
The signal is read at regular intervals and debounced on hardware level
•
An additional debounce time is available: 0…25.5 s (default = 0 s)
•
Pulses of more than 20 ms from pushbuttons are registered and kept ready for
polling
•
Desigo XWORKS plus:
Only D20 (N/O) is available. Inversion (D20R, N/C) must
be realized via inverting in the parameterization.
•
P-Bus BIM
: The configuration (D20. D20R) sets the contact type (N/O or N/C)
•
The meaning of the I/O status LED can be parameterized (TXM1.8D only):
Normal = green (default) / Alarm = Red / Service = Yellow.
•
The signal operation can be selected: Contact_NO (default), Contact_NC)
•
As a result
– The
I/O status LED
is activated.
– The
process value
is communicated over the bus
– The
LCD
is activated
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 or
N/C contact) and the state of the contact:
N/O contact /
N/C contact
Process value island bus
Process value
LCD-Display
I/O status LED
closed
open
active
inactive
10
56
1z
15
5
ON
OFF
N/O
N/C
> 20 ms
200 ms
P-Bus Polling
N/O
> 20 ms
Diagram: Cause and effect
For details, especially in relation to flashing pattern and errors: refer to the section "Dis-
play, operation and diagnostics" in the TX-I/O™ Engineering and installation guide [6].
Local override
Display