Read Only

Parameter Read Only defines the initial Read-Only State of Tags and BLOCK:PARAMETERS built using this parameter.   Parameter Read Only can save time and typing or enforce a standard if this parameter will be used in a predictable way to create Tags or Blocks. Specifies that the Tag's or BLOCK:PARAMETER's real-time value (the output value) is read only.  If READ ONLY is selected, users and operators cannot change the value of the Tag or Block Parameter in run-time VIEW. Only the field device can update the value of the tag.  Alarm Limits and other tag fields are changeable. Typically used with measurements and Input type tags and parameters.

If you want to allow some users to change the value of the tag, but not all users, consider assigning a security Area or Level to the tag or block.