Can I read a valve opening value via communication on a position proportional controller?

Yes. Data in D register number D2005 is the valve opening value. Note that with a position proportional controller, D2006 is the PID computed value.

Advanced Application UT75A

Temperature Controller with increased monitoring and operating capabilities
Mid-level UT55A/UT52A

Increase monitoring and operating capabilities
UP35A/UP32A

Program Controllers with 4 patterns, 40 segments, and ladder sequence functions
UP55A

Program controller with 30 patterns, simultaneous monitoring, and ladder sequence function
UT35A/UT32A

Increase monitoring and operating capabilities