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Answered

Bidirectional Prop. Valve input

christophe 3 years ago in IQANdesign updated by Gustav Widén (System support) 3 years ago 2

I have an MD4-5 and XC-21. Another measurement system gives output for 2 bidirectional prop valves. (24V 3Amax.) how can I measure this values with one of the modules?
The max current in is limited to a few Mili amps and the voltage in is limited to 5vdc.
PWM could be an option but there ate only 3 available on the xc21


Tips are welcome!


EXTRA QUESTION: is it possible to connect a 24dc PWM signal directly to the MC43?


+1
Answered

It is possible to read the pulse width of a PWM signal using the XC21 PWMIN channels. 

If it works in the application depends on whether the signal will meet the trig levels the PWMIN looks at. The XC21 is as most IQAN modules specified for < 1 V and > 4 V as trig level, see XC21 appendix A



To have any chance of coming below the 1 V low threshold when connecting a PWM power driver to an XC21 PWMIN input, there must be an external load connected. The XC21 PWMIN pull-down alone would not be enough to get below this trig level. The exact value will depend on the leakage current of the module with the PWM power driver.