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An interesting problem: Read-only Screens - Disable Touchscreen while keeping RA operational

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I'm having a very interesting issue that requires creative thinking ;)

Imagine having 3 - 4 Vision PLCs with a touchscreen, working in the field, which are all connected to Control Room via Unitronics Remote Operator software.  I want for the Remote Operator to be able to use the PLCs, but for a local operator to have no access - only view screen contents. PLC should not accept any touches.

So, the Control Room operator has all the HMIs on his computer screen, and can do whatever he wants on the PLCs: click on buttons, enter variables, change screens, etc.

But a local operator can only watch the PLC screen. He can make touches but PLC will ignore them.

Now, the twist: the Control Room operator should be able to remotely "activate" touchscreen on the PLCs, allowing local operator to use it for a limited time. Then, after a timer runs out, or the CR operator clicks on a button, the PLCs switch back their HMI to "Read-only" mode.

Would this be possible with Vision?

I mean, technically, I could cannibalize the touchscreen cable, install a relay or some analog multiplexer which turns it off when a certain output is on. Unfortunately that would void the warranty of the PLCs, and would be rather brutal.

Any ideas?

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  • MVP 2023

One of possible way - assign some ON touch hidden key (or keys) on screen (small,  flat and the same color as the display) - this key or many key's (named "SET touch prop flag" for one touch).

Control Room operator must touch it before use some touch element. If touch element activated - "SET touch prop flag" RESET. local operator can only watch the PLC screen - it cannot see the mouse cursor.

If one hidden combination password entered ( more than 3 different hidden touch - like temporary password) -  Control Room operator give to the local some time (by timer)


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14 hours ago, Flex727 said:

Set up a log in for the Control Room operator. When not logged in, the buttons are disabled on the screen. You can have the log in time out which would return the buttons to the disabled state.

This sounds like a good idea. All screen buttons have a Disable bit if there's no user logged in.

In every screen I could place a tiny button at the top, which is hard to be pressed by a local operator (because it's only 3x3 pixels wide for example). But it can be pressed using Remote Operator (because screen is bigger, and there's mouse). Remote operator presses the hidden button, enters the password, local user doesn't see the password because it shows as ******, and it enables, say, 5 minutes of PLC use. After that the Remote operator presses the tiny button again and locks the panel.

Even easier, there could be no password, just the hidden touch element which turns on and off Disable buttons bit. Thanks!

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