Using OPC Server

[Chris]

I would like to to expose specific tags to the OPC server, and have these set as read only.
Can this be done?
For instance, suppose I have 100 analogue tags configured, but I need to expose 10 of these, but only for reading. How would I do this?

[Frits]

I’m assuming you are scanning from an OPC Server into Analog Agents? If the scanning configuration is not output enabled, it will not write back to the OPC Server i.e. Read-Only. Only Output-Enabled scanning will allow the writing of values back to the device.

[damiand]

Hi Chris,
On the other hand, if You want to expose Agent Server agents to Adroit OPC Server, please follow Help topic from the software:
Automatically Populating the OPC Server Item Browser Window

If enabled, this allows the MAPS SCADA OPC Server application to automatically populate the item address browser to allow clients to browse for items.

Note: By default, this feature is disabled, since experience has shown that Agent Servers tend to contain thousands of agents, which affects the browser performance.

To enable the automatic item address browser population:

1. Click on the Edit menu and select Properties .
2. Ensure that the Populate browser option is either ticked to enable this or cleared to disable this feature.

Note: If enabled, this will affect the performance of the system if there are a large number of tags.

Configuring which tag combinations populate this window:

While an OPC client can connect to any agent.slot combination, the MAPS SCADA OPC Server does not make all these combinations available to the OPC Server item-address browser for performance reasons.

However, you can choose which tags (agent.slot combinations) to display in the item-address browser of the MAPS SCADA OPC Server, as follows:

Automatically populating this window with tags:

Each AgentGroup agent (which provide a means of logically grouping agents) provides a exposeViaOpc slot (the Slots to expose via OPC Server (comma separated) field, which allows you to specify which slots, of the agents that have been added to this group, that you want to be populate the item-address browser of the MAPS SCADA OPC Server with. Simply type in the required slots, separated by commas “,”. For details, see The AgentGroup Agent.

Any AgentGroup whose exposeViaOpc slot is not empty, lists its contained agents and all their specified slots, when the Populate browser option of the MAPS SCADA OPC Server is enabled.

Typically an AgentGroup agent is automatically created for each agent type and by default their exposeViaOpc slots are empty.

Manually specifying tags to display in this window:

In addition to these automatically retrieved agent-slot combinations, you can also specify discrete tags via the following comma-delimited registry string value:

WARNING: Registry settings are recorded as ADVANCED information and should not be used unless you understand exactly how these will affect the operation of your MAPS SCADA installation, IF YOU HAVE ANY DOUBTS, PLEASE CONTACT MAPS SCADA SUPPORT, BEFORE CHANGING THE REGISTRY.

PLEASE NOTE: When working on a 64 bit operating system, remember to add “\Wow6432Node” to the path of each registry setting after “\SOFTWARE”, for instance: “HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Adroit Technologies”.

HKEY_LOCAL_MACHINE\SOFTWARE\Adroit Technologies\Adroit\OPC Server\Browse tags .

This value can specify a comma delimited set of tags, in the format: agentname1.slotname1,agentname2.slotname2 etc.

As You can see, there is no option to lock specific tags via OPC settings, but You can do that as Frits described: if an agent has no output-enabled option to PLC scan, it will behave as read-only.