Online Forums

Technical support is provided through Support Forums below. Anybody can view them; you need to Register/Login to our site (see links in upper right corner) in order to Post questions. You do not have to be a licensed user of our product.

Please read Rules for forum posts before reporting your issue or asking a question. OPC Labs team is actively monitoring the forums, and replies as soon as possible. Various technical information can also be found in our Knowledge Base. For your convenience, we have also assembled a Frequently Asked Questions page.

Do not use the Contact page for technical issues.

Write to Tag demo

Start
Prev
1
Next
End

1

support
Away
Moderator

More

09 Oct 2024 18:44 #13216 by support

Replied by support on topic Write to Tag demo

Hello.

From our point of view, this is controlled by the OPC server, and the OPC specifications do not tell *how* it is done - it can differ for each server. Some may have it fixed, some configurable, some may use access rights from a downstream system. I would ask the server vendor for more info.

There is generally no way to control the access rights through OPC programmatically.

Best regards

Please Log in or Create an account to join the conversation.

tlaford
Topic Author
Offline
Elite Member

More

09 Oct 2024 18:27 #13215 by tlaford

Replied by tlaford on topic Write to Tag demo

When I execute this line:

object value = client.ReadItemValue("localhost","myServer.OPC.ServerClass","MyMachine.My.Tag.Name")

It returns a string.

When I try to change that string using this code:

client.WriteItemValue("localhost","myServer.OPC.ServerClass","MyMachine.My.Tag.Name","myValue")

it throws an exception

The Items AccessRights do not allow the operation.
+ The client method called (or event/callback invoked) was 'WriteMultipleItemValues[1]'.

What controls the AccessRights? Is it controlled by the OPC server itself, by the "gateway" program that allows me to communicate from my computer to the actual machine, or is it something that can be controlled programmatically?

Please Log in or Create an account to join the conversation.