https://forge.codesys.com/forge/talk/Engineering/thread/6e785f0e78/2026-05-07T08:27:51.189000ZRecent posts to CodeSys OPC UA client Unable to Connect To OPC UA sever through Username and password2026-05-07T08:27:51.189000Z2026-05-07T08:27:51.189000Zkiranbsiddaiahhttps://forge.codesys.com/u/kiranbsiddaiah/https://forge.codesys.com5ca419146b561a18396e627bf4b3def047d4bf5c

<div class="markdown_content"><p>And also we do not have any opc ua related license . Do we need to have a opc ua license to communicate with OPC UA server with username and password</p></div>

2026-05-07T03:08:24.323000Z2026-05-07T03:08:24.323000Zkiranbsiddaiahhttps://forge.codesys.com/u/kiranbsiddaiah/https://forge.codesys.com53324f1c510efa2fe8857e41c38b438661a06d10

<div class="markdown_content"><p>Hi,</p> <p>I'm using codesys v3.5 sp21 software. I have downloaded the sample opc ua client project from <a href="https://content.helpme-codesys.com/en/CODESYS%20Examples/_ex_uacapi_example.html" rel="nofollow">https://content.helpme-codesys.com/en/CODESYS%20Examples/_ex_uacapi_example.html</a> and i tested connecting to "prosys opc ua simulation server".</p> <p>Through Anonymous connection it is <strong>connecting</strong> to server and can read data. </p> <p>Later tried to connect using <strong>username and password</strong>. <br/> First got a <strong>SECURITY_CHECKS_FAILED</strong> error, trusted the client certificate in the server and this issue resolved.<br/> Next got an <strong>INVALID_CERTIFICATE</strong> error, trusted the server certificate in the client and this issue resolved.<br/> After these two error it is not <strong>establishing</strong> the connection and not giving any error messages.</p> <hr/> <p>UAAsyncProp: UA.AsyncProperty := (tnTaskName:='UAClientTask', usiTaskPrio:=20, udiTaskInterval:=10000);<br/> UAPolicy: UA.SecurityPolicy := (sPolicy:=UA.OpcUa_SecurityPolicy.OpcUa_SecurityPolicy_Aes128Sha256RsaOaep, eSecurity:=UA.SECURITY_MODE.SIGN_AND_ENCRYPT);<br/> //UAPolicy: UA.SecurityPolicy := (sPolicy:=UA.OpcUa_SecurityPolicy.OpcUa_SecurityPolicy_None, eSecurity:=UA.SECURITY_MODE.NONE);<br/> UAAuth: UA.UserNameAuth := (sUserName:=UAVars.sUser, sPassword:=UAVars.sPass);<br/> UAClient: UA.Client := (<br/> itfAsyncProperty:= UAAsyncProp, <br/> //sClientName:= 'MyOPC UA client name', //default: ‘CODESYS OPC UA Client’<br/> sURL:= UAVars.sURL,<br/> sSession:= UAVars.sSession,<br/> itfPolicy:= UAPolicy,<br/> itfAuth:=UAAuth,<br/> udiTimeout:= 100000<br/> //,itfNamespaceArray:= UAVars.itfNamespaceArray //optional use<br/> );<br/> -----------------------------------------------------------------------------------------------------------------------</p> <p>Please let me know if any additional information required.</p> <p>Thank you...</p></div>