Discover Available HDA Servers

Prerequisites

To interact with an OPC server, you must provide:

The host name of the computer on which the OPC server is installed. Typically the host name is a descriptive term (such as 'plantserver') or an IP address (such as 192.168.2.205).
The server ID of the server you want to access on that host. Because a single computer can host multiple OPC servers, each server installed on that computer is given a unique ID during installation.

Your network administrator can provide the host names for all computers with OPC servers on your network. You can also obtain a list of server IDs for each host on your network, or use the opcserverinfo function to access server IDs from a host, as described next.

Determine HDA Server IDs for a Host

When an OPC server is installed, it must be assigned a unique server ID. This server ID provides a unique name for a particular instance of an OPC server on a host, even if multiple copies of the same server software are installed on that same machine.

To determine the server IDs of the OPC servers installed on a host, call the opchdaserverinfo function, specifying the host name as the only argument. When called with this syntax, the function returns a structure containing information about all the OPC servers available on that host:

info = 
1x4 OPC HDA ServerInfo array:
 index    Host     ServerID                    HDASpecification            Description                   
 ----- ---------  ---------------------------------  --------  ------------------------------------------------
  1    localhost  Advosol.HDA.Test.3                 HDA1      Advosol HDA Test Server V3.0
  2    localhost  IntegrationObjects.OPCSimulator.1  HDA1      Integration Objects OPC DA DX HDA Simulator 2
  3    localhost  IntegrationObjects.OPCSimulator.1  HDA1      Integration Objects' OPC DA/HDA Server Simulator
  4    localhost  Matrikon.OPC.Simulation.1          HDA1      MatrikonOPC Server for Simulation and Testing

The fields in the structure returned by opchdaserverinfo provide this information:

Server Information Returned by opchdaserverinfo

Field	Description
`Host`	Character vector that identifies the name of the host. Note that no name resolution is performed on an IP address.
`ServerID`	Cell array containing the server IDs of all OPC servers accessible from that host.
`HDASpecification`	Cell array containing the OPC Specification that the server provides.
`Description`	Cell array containing descriptive text for each server.