Pwm Pulse Width Modulation (Bo Pwm, With Triac) - Siemens TX-I/O TXM1.8D Functions And Operation

Application
Hardware
Function
Parameterization
Parameter
TimePeriod
MinOnTime
MinOffTime
BackupMode
AOBackup
Value
Pulse pattern
Case A: TimePeriod ≠ 0
Siemens
Building Technologies
5.10 PWM Pulse width modulation
(BO PWM, with triac)
Open/close modulating actuators e.g. for
– Thermal valve actuators
– Continuously controlled consumers (e.g. electric heating controlled via current valve)
 Remember to check the permissible switching frequency of the connected
devices and adapt output parameterization.
• Only TXM1.8T module supports this function
• The function uses one I/O point
• AC 24 V supply, the triac closes the contact to ⊥ (system neutral)
• Technical data (max triac load): See module data sheet N8179
• The outputs work noise-free
The function converts the analog process value AOValue to a periodic switching pulse
of the triac.
Normally, pre-parameterized outputs are used customized to the actuators to be
operated.
The following parameters are available for individual parameterization:
Description
Switching cycle
(0 = Special behavior)
Min. switch-on time
– Protection against excessive switching
frequency
– Preheating ensures that the thermal
actuators open quickly
Min. switch-off time
– Protection against excessive switching
frequency
– Ensures that the thermal actuators close
safely
Backup state in the case of Masterdown
Pulse duration
These parameters allow for generating the following pulse patterns.
The analog output AOValue generates the following switch-on ratio (scan ratio)
OnPeriod = AOValue * TimePeriod
TimePeriod
OnPeriod
Min. switch-on/-off times can be parameterized as an option to protect against
excessive switching frequency. The triac does not switch on/off if the calculated switch-
on / switch-off time is less than MinOnTime / MinOffTime.
TX-I/O™ Module system – Functions and operation
Digital output functions
Value range Default
0...6553.5 s 20 s
0...25.5 s 1 s
(1...25.5 s, if
TimePeriod = 0)
0...25.5 s 1 s
(1...25.5 s, if
TimePeriod = 0)
Keep No
No
Value
0.00...100.00% 0 %
t
Increment
0.1 s
0.1 s
0.1 s
1/100 %
45/54
CM110561en_08
2018-10-25