The issue is most likely caused by the OPC Security system locking you out due to either a missing ACL.sec file or a corruption. The classic sign of this is the configured aliases folder will be missing.
Please do the following:
*Ensure that you are logged in to Windows as an Administrator user, close the OPC Server GUI if open**
1) Open a command prompt in elevated mode - Start>cmd then right click and choose Run as Administrator
2) cd \ [ENTER]
3) cd "program files (x86)\Matrikon\opc\allen Bradley plcs" [ENTER]
4) aclsecure.exe -d MatrikonOPC [ENTER]
You should see a message advising the decryption was successful. If not, take note of the error. If it says aclsecure.exe is unrecognized, please check you are in the correct directory and the file is missing, then contact Matrikon OPC Support at
support@matrikonopc.com and request they send you the file.
5) aclsecure.exe -e MatrikonOPC [ENTER]
You should see a message advising the decryption was successful.
6) Close the command prompt window
7) Open Windows Services (Start>services.msc)
8) Locate MatrikonOPC Server for Allen Bradley PLCs and restart it if stopped, or just start it
9) Retry OPC Explorer, the issue should be resolved.
