# ARSim monitoring - "Connection to OPC UA server not possible" **URL:** \ **Category:** B&R Software & Runtime\ **Tags:** arsim\ **Created:** [December 4, 2024, 10:48pm UTC](https://community.br-automation.com/t/arsim-monitoring-connection-to-opc-ua-server-not-possible/5123 "2024-12-04T22:48:28Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![david.christensen](https://avatars.discourse-cdn.com/v4/letter/d/FF8800/32.png) [@david.christensen](https://community.br-automation.com/u/david.christensen)\ **Post date:** [December 4, 2024, 10:48pm UTC](https://community.br-automation.com/t/arsim-monitoring-connection-to-opc-ua-server-not-possible/5123/1 "2024-12-04T22:48:28Z")
I’m new to Automation Studio (using v 6.0.2.177), and I’m trying to learn to program via ARSim. I setup a test project with a Standard PC and transferred a simple program. When I click the ‘monitor’ button, I get an error of “Connection to OPC UA server not possible.” ---
**Author:** ![christoph.hilchenbac](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/christoph.hilchenbac/32/423_2.png) [@christoph.hilchenbac](https://community.br-automation.com/u/christoph.hilchenbac)\ **Post date:** [December 5, 2024, 12:55pm UTC](https://community.br-automation.com/t/arsim-monitoring-connection-to-opc-ua-server-not-possible/5123/2 "2024-12-05T12:55:16Z")
Hi David, just tried this. And no, I don’t get the fault. Are you sure this message is from AS ? Find my simple project attached. Regards, [xxx.zip](https://community.br-automation.com/uploads/short-url/k913TRQsCPw4sAiTFUAERCHZe1V.zip) (63.8 KB) ---
**Author:** ![david.christensen](https://avatars.discourse-cdn.com/v4/letter/d/FF8800/32.png) [@david.christensen](https://community.br-automation.com/u/david.christensen)\ **Post date:** [December 6, 2024, 6:10pm UTC](https://community.br-automation.com/t/arsim-monitoring-connection-to-opc-ua-server-not-possible/5123/3 "2024-12-06T18:10:41Z")
Christoph, Thanks for the sample project. Yes, your program runs fine. My project has a ladder program, which now seems to be what the issue is. When I add a ladder program to your project, I get the same OPC UA error. Strangely, my ladder program simulates just fine on v4.9. And the ladder program/project I’m running is based on the tutorial in the 6.0 help file: file:///C:/Program%20Files%20(x86)/BRAutomation/AS6/Help-en/Data/gettingstarted/firstproject.htm Maybe the tutorial was never updated for 6.0 and it’s missing some step? ---
**Author:** ![christoph.hilchenbac](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/christoph.hilchenbac/32/423_2.png) [@christoph.hilchenbac](https://community.br-automation.com/u/christoph.hilchenbac)\ **Post date:** [December 9, 2024, 8:41am UTC](https://community.br-automation.com/t/arsim-monitoring-connection-to-opc-ua-server-not-possible/5123/4 "2024-12-09T08:41:31Z")
Hi, i see, you started here: [B&R Online Help](https://help.br-automation.com/#/en/6/gettingstarted%2Ffirstproject.htm) if you just follow the tutorial then you probably get this: ![image](https://europe1.discourse-cdn.com/brcommunity/original/2X/5/5613527e4bdc703b33c6d2bab037fdcbf78ffc74.png) yep. it seems the configuration of OPC-UA and the user/role settings are missing in this tutorial ![image](https://europe1.discourse-cdn.com/brcommunity/original/2X/7/7b27bbed2d5b6264ab02bca86ba78dc1d872a165.png) ![image](https://europe1.discourse-cdn.com/brcommunity/original/2X/5/50d2daa8a77123d7d13d61c72dff92997cebdf37.png) if you miss the user/ role and activate the Monitor AS asks for the login data ![image](https://europe1.discourse-cdn.com/brcommunity/original/2X/b/be8890b26d09394a563efa9550b6d193a1ebbd08.png) find the new project attached where I used ‘user’/‘user’ for login Regards, [xxx.zip](https://community.br-automation.com/uploads/short-url/dAYilW0KIZhx2BbdwRTlqbkrJ6H.zip) (72.1 KB) ---
**Author:** ![david.christensen](https://avatars.discourse-cdn.com/v4/letter/d/FF8800/32.png) [@david.christensen](https://community.br-automation.com/u/david.christensen)\ **Post date:** [December 9, 2024, 5:57pm UTC](https://community.br-automation.com/t/arsim-monitoring-connection-to-opc-ua-server-not-possible/5123/5 "2024-12-09T17:57:00Z")
That seems to be the fix. It’s strange that disabling OPC UA in v4.9 creates no issues, but disabling it in v6.0 causes an error. Thanks for your help. I did actually just find this explained in the help file, and does explain why a ladder program has this issue, but not a text program: “Ladder Diagram editor in monitor mode In monitor mode, the Ladder Diagram editor communicates with the target system via OPC UA. The user role system and the OPC UA server must be configured accordingly for this.” ---
**Author:** ![kovarj](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/kovarj/32/537_2.png) [@kovarj](https://community.br-automation.com/u/kovarj)\ **Post date:** [November 12, 2025, 6:50am UTC](https://community.br-automation.com/t/arsim-monitoring-connection-to-opc-ua-server-not-possible/5123/6 "2025-11-12T06:50:31Z")
Split this topic on November 12, 2025, 6:50am UTC 4 posts were split to a new topic: [Port conflict causing OPC UA failure](https://community.br-automation.com/t/port-conflict-causing-opc-ua-failure/8991) ---
**Author:** ![kovarj](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/kovarj/32/537_2.png) [@kovarj](https://community.br-automation.com/u/kovarj)\ **Post date:** [November 12, 2025, 6:50am UTC](https://community.br-automation.com/t/arsim-monitoring-connection-to-opc-ua-server-not-possible/5123/7 "2025-11-12T06:50:49Z")
Closed on November 12, 2025, 6:50am UTC