I am having a problem with OMI Viewapp 2020

When you launch the OMI Web Application have you logged into the system with a user that has operate permissions against a security group that contains the instance (CALC_F8).  I am assuming that the attribute has Operate premissions assigned to it.

I am guessing you set the InputSource to a specific tag on the PLC, right? We may have to walk this through and try to figure out why this is happening:

1. Michael suggestion is also the first place I would look - we need to check the security:
   1. Is the Galaxy configured for security (Galaxy | Configure | Security) - and which type (Galaxy security is not recommended, we recommend using Windows OS User or Group or an external provider like Azure AD or CONNECT.)
   2. If security is configured, check in OMI:
      • A user must be logged in if security is enabled, otherwise any attributes not set to Free Access will not be writable.
      • If a user is logged in, make note of the username.
   3. Under the security configuration have a look at the Security Groups tab. Go through the security groups on the left and see which one contains CALC_F8 
   4. Now have a look at the Users Tab - Find your user in the "Authorized Users" list and note which Roles was assigned to it.
   5. Now have a look at the Roles tab - Select the roles on the left corresponding to your user's Roles - ensure that one of them has "Can Modify Operate Attribures" enabled under the Operational permissions
2. If security is not the issue, you can Open Object Viewer and bypass OMI.
   1. Rightclick the object (CALC_F8)
   2. Select Open in Object Viewer
   3. Once it is open, find your attribute (F8TSE_RET4_FINO_P3) on the right (you may want to sort by attribute name).
   4. Click and Drag it into the Watch window
   5. Now double-click it in the watch windo and try to change the value.
   6. If it does not work, there should be an error message telling you why.

If you still do not get it working, it may be better to get someone from Tech support to sit with you and troubleshoot the issue.  You can open an issue but sending an e-mail to wwsupport@aveva.com (or custfirstsupport@aveva.com if you are a Flex or Customer First subscriber).

Here is a troubleshooting tip that may help. In the Quality and Status settings enable the outline for each status and choose a unique color for each status, For example if you select purple for security then any time the attempted action is rejected due to security permission a purple outline will appear around your button. The internal messaging system carries the write status and these indicators are a simple way to add them everywhere without having to touch your symbols. You can leave them on or turn them off after you are done troubleshooting if you prefer. 

Thank you very much!

Thank you very much!