OPC UA node-red connection

[Fernando84]

Hello everybody!! I´m trying to connect my OPC UA client (node-red) to my server (Geo SCADA), now I'm reading the value from different analog points and the state of some boolean points. But when I try to write any value on the analog points or even when I tried to change the state on any boolean point it's not working, the value/state doesn't change. All the points I'm working with are internal points.

Any suggestion?

[sbeadle]

I see no reason why this should not work, except ... security, permissions etc?

[Fernando84]

Hi Steve,

where can I check those permissions? I used prosys OPC UA browser to connect to geo scada opc server and I noticed the variables that I try to write has only read permissions.

[AndrewScott]

For internal points you need to write to the CurrentValue property of the point and your user account needs have Control permission on the points (see Allocating Security Permissions).

I'm able to write to internal points using Matrikon OPC UA Explorer successfully.

[Fernando84]

Hi Andrew, I'm using the super user account to write in the current value property, do I need to use other account??

[AndrewScott · Accepted solution]

The super user is only intended to be used to do the initial system setup after which is should be disabled, see Super User Account in the help.

However, I'm able write a property using the super user account from Matrikon OPC UA Explorer providing it is running on the same machine as the Geo SCADA server. The super user cannot be used remotely.

[Fernando84]

Hello Andrew!

I made some tests using PROSYS OPC UA Browser, I tried with different users and the result is the same (image attached).  All the fields of the variables show "[current read]" as permission.  Any suggestion??

[sbeadle]

Check the type of the point. You can write to the current value of an Internal point, not a protocol (OPC or Modbus) point. 

Check the user account has "Control" permission on your Internal point.

[Fernando84]

Hi Steve! the points is an internal point (analog point), I'm trying to write the current value but it doesn't allow me.  The geoscada user that I'm using has contol and read permissions, but I can only read data.  If you want I can send you the flow (node red) that I'm using, so you can test it. 

[sbeadle]

Use the Geo SCADA OPC Driver to test controls first. If that works, Node Red is the problem.

[Fernando84]

Hi Steve, I followed your advise and I tried to write the current status for an internal digital point (boolean) from an OPC digital point, the two points are located in the same viewx, but I got this message (image attached). Any suggestion?

[sbeadle]

Goes back to Andrew's comment:

"For internal points you need to write to the CurrentValue property of the point and your user account needs have Control permission on the points (see Allocating Security Permissions).

I'm able to write to internal points using Matrikon OPC UA Explorer successfully."

Check server settings:

Check your point's security settings:

Check the UA user/password (which is a Geo SCADA User/Password) has "Control" privileges in its group.

[Fernando84]

Hi Steve!! everything in the geo scada (permissions) was fine, the problem was the user authentication on the OPC server, I fixed it and now it's working good.  Thank you!