Error with PLC connection

General Questions
1

Hi all, I am facing this error in PLC connectivity. I have some variables in Global variable list. With this variables, i am able to communicate from server to simulation but it seems impossible to communicate from Simulation to server. What could be the possible reason for this? Any leads will be much appreciated

Error
Error1254×399 147 KB

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2

Hover over the status icon to see what kind of error it is.
If the server lists the variables as read-only, you will need to see if those can be made read-and write on the server end.

3

Thank you ! that was actually the problem. The variables were read only.