Hi federico_moniglia21,

Are you sure the tag is changing and not being reset by the PLC? To test, simply drag the tag onto your screen. This should place an IO field that uses the tag as a process value.

Kind regards
Stefan

Hi federico_moniglia21,

• Do you see a warning on the IO field that would indicate a bad connection status to the PLC?
• Does the value of the IO field change between 0 and 1?
• Can you change the value with the IO field?

Kind regards
Stefan

Hi federico_moniglia21,

The default configuration of the IO field is to display the connection quality. Therefore, not seeing a warning icon in the IO field would indicate a good connection status.

At this point, I can think of three possible reasons for having a connection but not being able to change a value.

1. The HMI is writing the tag correctly within the PLC, but the PLC program immediately overwrites the value, causing it to behave as if the value cannot be written.
2. Security by default configuration makes it more difficult to configure the system so that communication can be set up correctly. However, the default would be to block all, so you would have already made some changes.
3. You are logged into the system as a user with the user role "HMI Monitor Client". In this case, you are not allowed to operate. However, the system will indicate this by surrounding the entire screen with a red frame.

For the first assumption, put the PLC in stop mode and try again if you can write a value.

For the 2nd option, please add an alarm control to your screen. The default configuration displays system alarms that should provide some details about a connection error.

For the third assumption, change your user configuration so that the "HMI Monitor Client" role is not used.

Your messages indicate that you are having problems with more than just the switch configuration. Therefore it is necessary to provide more information about the hardware you are using. In this answer I am referring to the use of modern S7-1200/1500 PLCs with integrated HMI connection. My answers may not apply to some other configurations.

Kind regards
Stefan