I am using Factorytalk ME and don't know how to set up push button expressions and tags.

I have two tags for open and close. I have two push buttons for open and close. I want to set them up the way that when open PB is pressed, it won't send the value if the close PB is already pressed.

 

Hi There,

This is a priority scenario.

You may just connect the PBs in series.

On pushing the NC (Normally Closed) PB, it opens the circuit. If you press any other PB in series, it wont pass the signal as the circuit is already broken.

This works only real time. (physical signals)

For factory talk, you may use the latching function of PB to achieve this.

Use a latched NC (Normally Closed) PB and a normal NO PB for this functionality.

The connection has to be in series like before.
And employ latching for the NC switch in the HMI. The signal may not be passed unless the NC switch is reset(According to the HMI).

Design depends on the functionality of the switches you are depending on.