Issue
The Xenta 102-AX PWM_1 (one output PWM) setting is a true duty cycle output. How can you control a PWM transducer?
Environment
Xenta 102-AX, Universal Output 2
PWM Transducer
Cause
The problem is that 0% on a duty cycle output is no pulse at all and 100% is continually on. All electronic transducers must have some pulse to control it to 0%, often 0.1 seconds. Many of them will not accept a continually on signal as 100%.
Values for two of the most industry common PWM transducers are detailed below. Calculations provided can be used to calculate any required duty cycle limits.
Resolution
This example assumes a PWM transducer that requires a pulse width modulated signal between 0.1 and 5.2 seconds.
-
Set the stroke time to a value slightly larger than the required maximum pulse.
UnivOut2_Object.SCPTdriveTime = 5.3 seconds -
Set the minimum range to a percentage of the drive time that will result in a 0.1 second pulsed output.
UnivOut2_Object.nviUnvOutput2.SCPTminRnge = 1.885%
0.01885 * 5.3 = 0.099905 seconds -
Set the maximum range to a percentage of the drive time that will result in a 5.2 second pulsed output.
UnivOut2_Object.nviUnvOutput2.SCPTmaxRnge = 98%
0.98 * 5.3 = 5.194 seconds - Set the minimum pulse to 0.1 second.
- A 0-100% signal on Universal Output 2 will now modulate the pulse width between 0.1 and 5.2 seconds.
This example assumes a PWM transducer that requires a pulse width modulated signal between 0.1 and 25.6 seconds.
-
Set the stroke time to a value slightly larger than the required maximum pulse.
UnivOut2_Object.SCPTdriveTime = 25.7 seconds -
Set the minimum range to a percentage of the drive time that will result in a 0.1 second pulsed output.
UnivOut2_Object.nviUnvOutput2.SCPTminRnge = 0.39%
0.0039 * 25.7 = 0.10023 seconds -
Set the maximum range to a percentage of the drive time that will result in a 25.6 second pulsed output.
UnivOut2_Object.nviUnvOutput2.SCPTmaxRnge = 99.61%
0.9961 * 25.7 = 25.59977seconds - A 0-100% signal on Universal Output 2 will now modulate the pulse width between 0.1 and 25.6 seconds.
