Siemens TX-I/O TXM1.16D, Functions And Operation, Page: 46 / 54

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Siemens TX-I/O™ Module system – Functions and operation CM110561en_08
Building Technologies Digital output functions 2018-10-25
MinOnTime and MinOffTime are used to dynamically define the pulse length (also
known as PDM, pulse duration modulation):
• Period =
MinOnTime
/ AOValue
if AOValue <= MinOnTime / ( MinOnTime + MinOffTime )
• Period = MinOffTime / (1- AOValue)
if AOValue > MinOnTime / ( MinOnTime + MinOffTime )
Period
Process value <= MinOnTime/(MiMinOffTime)
t
MinOnTime
Period
Process value > MinOnTime/(MiMinOffTime)
t
MinOffTime
Examples for cases A and B
Input Parameter Output
AOValue TimePeriod MinOnTime MinOffTime Period ON OFF
85% 10 s 1 s 1 s 10 s 8.5 s 1.5 s
80%
1)
30 s 4 s
8 s
1)
30 s 30 s
0 s (< MinOff)
1)
70% 30 s 4 s 8 s 30 s 21 s 9 s
50% 20 s 5 s 5 s 20 s 10 s 10 s
40% 30 s 1 s 1 s 30 s 12 s 18 s
20% 0 s 1 s 1 s 5 s 1 s 4 s
50% 0 s 2 s 1 s 4 s 2 s 2 s
50% 0 s 1 s 3 s 6 s 3 s 3 s
60% 0 s 1 s 1 s 2.5 s 1.5 s 1 s
60% 0 s 9 s 1 s 15 s 9 s 6 s
0.01%
2)
0 s 20 s 20 s
2)
6573.5 s
2)
20s 6553.5 s (limited)
2)
0% any any any -- ∞
100% any any any -- ∞
1)
Avoid. Long MinOffTime and MinOnTime values require a long TimePeriod , because
outputs near 0% and 100% are changed to 0% or 100%.
2)
Avoid. Inputs near 0% greatly extend period (process value AOValue has a
resolution of 0.01%). The max. limitation of the function is 6553.5 s (1.8 h), but a
period this long does not make any sense.
Therefore the minimum AOValue should be limited so that a reasonable max.
Period results.
If the process value (AOValue) changes, the function calculates a new pulse length
based on the active pulse.
• The I/O Status LED is light proportional to the process value
• In case of error, the I/O status LED is lit together with the module status LED.
Details, blinking pattern and errors in particular: See section "Display, operation and
diagnosis" in [6] "TX-I/O™ engineering and installation".
Quality value "No_Output" is output if AC 24 V is missing.
The triac can then not switch on

The module switches off the output and sets
process value to 0.
The error message is sent only if a positioning command is available.
Case B: TimePeriod = 0
Reaction to changes of
AOValue
Display
Error message