# OPC Client DA/UA can’t connect to node-red-contrib-opcua server **URL:** \ **Category:** Drivers\ **Created:** [November 17, 2020, 8:55am UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557 "2020-11-17T08:55:56Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![mommeja](https://avatars.discourse-cdn.com/v4/letter/m/eb9ed0/32.png) [@mommeja](https://community.factoryio.com/u/mommeja)\ **Post date:** [November 17, 2020, 8:55am UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557/1 "2020-11-17T08:55:56Z")
**Anybody can connect Factory I/O to Node-RED embedded server of node-red-contrib-opcua 0.2.89?** Since the version 2.4.5, the situation with [my problem](https://community.factoryio.com/t/opc-client-da-ua-cant-connect-to-server/508) to connect to node-opcua server has improved: Factory I/O connects to a stand alone server like a charm 😉 For my tests I’m using the very simple server shared by @brunovgr in problem “Node-opcua server”. My problem is that Factory I/O doesn’t want to connect to the embedded server (node OpcUa-Server) of node-red-contrib-opcua 0.2.89. I get exactly the same message than in my previous problem 28 days ago with a standalone server: _\> Server did not return an endpointdescription that matched the one used to create the secure channel_ However, I can connect to the Node-RED embedded server with the stand alone node-opcua-sample client =\> this is the reason why I think Factory I/O OPC Client DA/UA driver has still a problem [Screenshot 2020-11-17 094411 fio|690x353](https://community.factoryio.com/uploads/short-url/3sY4d5SS1pdObsi1R7mOQSuSbIA.jpeg) Thanks for your help! ---
**Author:** ![brunovgr](https://dub1.discourse-cdn.com/flex017/user_avatar/community.factoryio.com/brunovgr/32/12_2.png) [@brunovgr](https://community.factoryio.com/u/brunovgr)\ **Post date:** [November 18, 2020, 10:14am UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557/2 "2020-11-18T10:14:00Z")
@mommeja I believe it’s a certificate related problem. I’m unable to connect to recent versions of node-opcua with any other opc ua client (even by changing certificates between server and client). I tried several opc ua clients such as Prosys, Softing, etc, but without success. The included node-opcua-sample client is the only one that works. Maybe you could submit an issue to the node-opcua team: [https://github.com/node-opcua/node-opcua/issues](https://github.com/node-opcua/node-opcua/issues) ---
**Author:** ![mommeja](https://avatars.discourse-cdn.com/v4/letter/m/eb9ed0/32.png) [@mommeja](https://community.factoryio.com/u/mommeja)\ **Post date:** [November 18, 2020, 10:32am UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557/3 "2020-11-18T10:32:57Z")
> [@brunovgr](#): > > ybe you could submit an issue to the node-opcua tea @brunovgr I suspect a certificate problem too, for the following reason: I have at least one OPC-UA client (other than node-opcua clients) that works with node-opcua: **Unified Automation UAExpert**. The first time I’m connecting this client to node-opcua (the one embedded in Node-RED), UAExpert is asking me to trust the server certificate (see screen capture attached). Once I explicitly trust it, UAExpert is putting the certificate into its own trusted certificate store, and then it works well. So at this time, I am trying to follow **Factory I/O OPC UA Certificates and User Identity** [documentation](https://docs.factoryio.com/manual/drivers/opc/) to reproduce the same logic than with UAExpert. ![UAExpertAskTrust](https://europe1.discourse-cdn.com/flex017/uploads/factoryio/original/1X/14e0cc40456d2d03417ca39a17400fb3d3a7ae1f.jpeg) ---
**Author:** ![mommeja](https://avatars.discourse-cdn.com/v4/letter/m/eb9ed0/32.png) [@mommeja](https://community.factoryio.com/u/mommeja)\ **Post date:** [November 19, 2020, 6:47pm UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557/4 "2020-11-19T18:47:55Z")
@brunovgr it’s actually not a problem with certificates. Strangely, when Factory I/O requests a session creation to the opc ua server, it passes it’s endpoint url with lower case letters. This results into a url mismatch if the endpoint url is actually not in lower case. In this situation the session creation request is rejected. About wether or not a url is case sensitive, the w3c states: > URLs in general are case-sensitive (with the exception of machine names). There may be URLs, or parts of URLs, where case doesn’t matter, but identifying these may not be easy. Users should always consider that URLs are case-sensitive. [https://www.w3.org/TR/WD-html40-970708/htmlweb.html](https://www.w3.org/TR/WD-html40-970708/htmlweb.html) I believe Factory I/O should avoid transforming the endpoint url. Do you know where I can create an issue? ---
**Author:** ![brunovgr](https://dub1.discourse-cdn.com/flex017/user_avatar/community.factoryio.com/brunovgr/32/12_2.png) [@brunovgr](https://community.factoryio.com/u/brunovgr)\ **Post date:** [November 20, 2020, 11:00am UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557/5 "2020-11-20T11:00:22Z")
@mommeja Can you tell me the steps you followed to identify this problem? I don’t see any problem in the OPC UA code, maybe the problem resides in the middleware we are using. ---
**Author:** ![mommeja](https://avatars.discourse-cdn.com/v4/letter/m/eb9ed0/32.png) [@mommeja](https://community.factoryio.com/u/mommeja)\ **Post date:** [November 20, 2020, 11:30am UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557/6 "2020-11-20T11:30:56Z")
> [@brunovgr](#): > > be the problem resides in the middle @brunovgr I added a trace point in the server code when the request is coming from the client. Look at line 1560 here [https://github.com/node-opcua/node-opcua/blob/master/packages/node-opcua-server/source/opcua\_server.ts](https://github.com/node-opcua/node-opcua/blob/master/packages/node-opcua-server/source/opcua_server.ts) Using contrib node-red-contrib-opcua, I actually added a trace point to the generated .js code in .node-red\node\_modules\node-opcua-server\dist\opcua-server.js My test endpoint is: **opc.tcp://LAPTOP-J7AHFDQH:53880** Trace when **UA Expert** connects to my server: > ``` > { > "requestHeader": { > "authenticationToken": "ns=0;b=c6474ce444911d34fad3b32a6a6d8147", > "timestamp": "2020-11-19T18:30:10.251Z", > "requestHandle": 1001426, > "returnDiagnostics": 0, > "timeoutHint": 10000 > }, > "clientDescription": { > "applicationUri": "urn:LAPTOP-J7AHFDQH:UnifiedAutomation:UaExpert", > "productUri": "urn:UnifiedAutomation:UaExpert", > "applicationName": { > "text": "Unified Automation UaExpert" > }, > "applicationType": "Client", > "discoveryUrls": [] > }, > "endpointUrl": "opc.tcp://LAPTOP-J7AHFDQH:53880", > "sessionName": "urn:LAPTOP-J7AHFDQH:UnifiedAutomation:UaExpert", > "clientNonce": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=", > "requestedSessionTimeout": 1200000, > "maxResponseMessageSize": 67108864 > } > > ``` Trace when **Factory I/O** connects to my server: > { > “requestHeader”: { > “authenticationToken”: “ns=0;i=0”, > “timestamp”: “2020-11-19T18:30:12.118Z”, > “requestHandle”: 1, > “returnDiagnostics”: 0, > “timeoutHint”: 0 > }, > “clientDescription”: { > “applicationUri”: “urn:LAPTOP-J7AHFDQH:Factory IO”, > “productUri”: “urn:company:product”, > “applicationName”: { > “text”: “Factory IO” > }, > “applicationType”: “Client”, > “discoveryUrls”: > }, > “serverUri”: “urn:NodeOPCUA-Server-default”, > “endpointUrl”: “opc.tcp://laptop-j7ahfdqh:53880/”, > “sessionName”: “OPC UA Driver”, > “clientNonce”: “WtJbuD6CdvlNxVaxCvAAcmPdCrKWjS8Uays4J67uD7w=”, > “requestedSessionTimeout”: 60000, > “maxResponseMessageSize”: 10485760 > } If you want to do a WebEx, or call me, please send a mail to [mommeja@fr.ibm.com](mailto:mommeja@fr.ibm.com) ---
**Author:** ![brunovgr](https://dub1.discourse-cdn.com/flex017/user_avatar/community.factoryio.com/brunovgr/32/12_2.png) [@brunovgr](https://community.factoryio.com/u/brunovgr)\ **Post date:** [November 23, 2020, 5:50pm UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557/7 "2020-11-23T17:50:32Z")
@mommeja Thanks for your valuable feedback and for being so helpful. I don’t think the problem is related to letter case. My point is, all OPC clients I test against the sample server (node\_modules\node-opcua-samples\bin\>node simple\_server.js) report this error message. We are currently investigating this issue and once we have something to share I’ll post it here. ---
**Author:** ![mommeja](https://avatars.discourse-cdn.com/v4/letter/m/eb9ed0/32.png) [@mommeja](https://community.factoryio.com/u/mommeja)\ **Post date:** [November 24, 2020, 8:42am UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557/8 "2020-11-24T08:42:03Z")
> [@brunovgr](#): > > issue and o I advise you to test with the OPC-UA server (OpcUa-Server) embedded in Node-RED (node-red-contrib-opcua). It’s a real server. My tests: OpcUa-Client \> OpcUa-Server **ok** node-opcua-sample/simple\_client.js \> OpcUa-Server **ok** UAExpert OPC UA Client \> OpcUa-Server **ok** ProSys OPCUA Browser \> OpcUa-Server **ok** Factory I/O OPC UA/DA \> OpcUa-Server **ko** Factory I/O OPC UA/DA \> node-opcua-sample/sample\_server.js **ok** ProSys OPCUA Browser \> node-opcua-sample/sample\_server.js **ok** UAExpert OPC UA Client \> node-opcua-sample/sample\_server.js **ok** ---
**Author:** ![brunovgr](https://dub1.discourse-cdn.com/flex017/user_avatar/community.factoryio.com/brunovgr/32/12_2.png) [@brunovgr](https://community.factoryio.com/u/brunovgr)\ **Post date:** [November 27, 2020, 9:18am UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557/9 "2020-11-27T09:18:41Z")
@mommeja I have just received feedback from our middleware provider and you are absolutely correct. The toolkit we use in our OPC UA driver is making the Uri lower case and terminating it with the ‘/’ character, which is not accepted by the server. We are working on a preview release which will include several fixes, including this one. We are doing our best to release it as soon as possible. ---
**Author:** ![brunovgr](https://dub1.discourse-cdn.com/flex017/user_avatar/community.factoryio.com/brunovgr/32/12_2.png) [@brunovgr](https://community.factoryio.com/u/brunovgr)\ **Post date:** [December 18, 2020, 4:07pm UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557/10 "2020-12-18T16:07:54Z")
@mommeja We have just released Factory I/O v2.4.6 (Preview 2) which includes a fix addressing this issue. You can find it here: [Factory I/O v2.4.6 preview 2 available](https://community.factoryio.com/t/factory-i-o-v2-4-6-preview-2-available/618) ---
**Author:** ![mommeja](https://avatars.discourse-cdn.com/v4/letter/m/eb9ed0/32.png) [@mommeja](https://community.factoryio.com/u/mommeja)\ **Post date:** [December 18, 2020, 5:28pm UTC](https://community.factoryio.com/t/opc-client-da-ua-can-t-connect-to-node-red-contrib-opcua-server/557/11 "2020-12-18T17:28:05Z")
Bruno excellent! We will download it.