Siemens TX-I/O TXM1.8X-ML - Page 46

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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/(MinOnTime+MinOffTime)
t
MinOnTime
Period
Process value > MinOnTime/(MinOnTime+MinOffTime)
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