Urgent question about NT31C: how PLC knows which screen number is being displayed?

[Winall 0]

Hi, I'm having a NT31C touch screen, connecting to a C200HE PLC CPU. My task is let the PLC know which screen number on NT31C is being displayed. NT30C, the previous version of NT31C, has a PT Status Notify Area where it writes the current screen number being displayed to the designated host PLC word. But NT31C doesnt. Can anyone help urgently. Thanks.

[PdL 71]

What makes you think this?

[PMCR 66]

The NT30 and NT31 handled this differently. On the NT30, the screen could be controlled by writing to the first word of the PT Control area, and the current screen number could be monitored in the first word of the PT Notify area. On the NT31, the screen can still be controlled by writing to the first word of the PT Control area, but the current screen number is also now shown in the same word. So, the first word of the PT Control area can be written to if you want to change screens, but it also changes when the screen changes to a different screen. It performs both tasks that were previously seperate in the NT30. See this topic as well. http://forums.mrplc.com/index.php?showtopi...amp;#entry81601 Edited 7 May 2009 by PMCR

[Winall 0]

Thanks for all your contribution. Since this area is used for both PT notify & PT control, I found a way to know it by detecting the screen switch strobe and then check the PT Status Control Area.