Edge Gateway OPC DA Adapter

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OPC DA using DCOM Protocol

OPC DA Protocol Connection

server_host	String	ip address or host name of the OPC DA server.
server_domain	String	In case the user is a domain user, specify the Windows domain with this attribute.
cls_id	String	DCOM class id for the OPC server. Details of how to get it are mentioned below
prog_id	String	Optional. DCOM prog id for the OPC server.
username	String	Specify the user we added in the DCOM configuration section above
password	String	Specify the corresponding password

How to find the OPC server’s DCOM class id?

1. In the start menu, type regedit.
2. expand HKEY_CLASSES_ROOT and look for the name that matches your OPC server.
3. Once found, expand it and you will find a key named CLSID
4. Copy the corresponding value. This is your class id. Note that you need to ignore the curly braces around the ID.

OPC DA Read Tag

tag_id	String	Unique tag id defined in the context of the current thing_config. This is used further in metric_mappings or derived_tags or scan_tag_ids or monitor_tag_ids to refer to this tag value
node_id	String	The OPC DA tag definition which is present at OPC DA server e.g. ns=2;s=Channel1.Machine1.Tag1 or ns=0;i=2259. The format for tag is as follows: ns=<namespace id>;s=<string identifier of the tag> OR ns=<namespace id>;i=<integer identifier of the tag> For example: ns=2;s=Channel1.Machine1.Tag1

DCOM configuration on the OPC Server

The Datonis Gateway acts as a OPC client while fetching data from an OPC server. The default DCOM settings for a Windows host do not permit this communication. Thus it becomes necessary to make appropriate configuration changes so that this communication goes through.

1. Create a local Windows user called “altizon” on the OPC server machine.
   1. Right click Computer and click Manage
   2. Under Computer Management -> Users and Groups -> Users, right click and select New User…
   3. Set an appropriate password
   4. Uncheck all options and then only check the Password never expires option
   5. Also, add it to the Administrators group
2. In the start menu, in search/run, enter dcomcnfg
3. Under Console Root -> Component Services -> Computers -> My Computer, right click and select properties
4. In the COM Security tab, under Access Permissions
   1. click Edit Limits…, In the pop up window that opens, click Add… and select the user we added in step 1.
   2. Select both checkboxes Local Access and Remote Access under Allow
   3. click Edit Defaults… In the pop up window that opens, click Add… and select the user we added in step 1.
   4. Select both checkboxes Local Access and Remote Access under Allow 

1. In the COM Security tab, under Launch and Activation Permissions
   1. click Edit Limits… In the pop up window that opens, click Add… and select the user we added in step 1.
   2. Select all checkboxes under Allow
   3. click Edit Defaults… In the pop up window that opens, click Add… and select the user we added in step 1.
   4. Select all checkboxes under Allow

1. Under Console Root -> Component Services -> Computers -> My Computer -> DCOM Config look for the entry corresponding to your OPC server. Right click and select Properties
2. In the Identity tab, select the user to The Interactive user.

1. Reboot the machine. Reboot is required for these changes to take effect