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%% Read and Write Data to an OPC Data Access Server % This example shows you how to use OPC Toolbox(TM) synchronous read and % write operations to exchange data with an OPC server. % % *PREREQUISITES:* % % * <docid:opc_examples.example-ex84291595> % Copyright 2004-2016 The MathWorks, Inc. %% Connect to Server and Create Objects % Create an |opcda| client and connect that client to the OPC server. da = opcda('localhost', 'Matrikon.OPC.Simulation.1'); connect(da); %% % Add a group to the client, and an item to the group. grp = addgroup(da); itm1 = additem(grp, 'Random.Real8'); %% Perform Synchronous Read Operations % The default read operation gets values from the server cache. r = read(itm1) %% % Specify the source of the read as |'device'| to force the server to read a value from the device. % This process may take long if the OPC server is on the % network or the device takes some time to produce a value. r = read(itm1, 'device') %% Perform Synchronous Write Operations % Add a writable item to the group. itm2 = additem(grp, 'Bucket Brigade.Real8') %% % Write the value 10 to the item. write(itm2, 10) %% % Read the value back into MATLAB(R). r = read(itm2, 'device') %% Read From Multiple Items % You can read data from multiple items using the group object. r = read(grp) %% % Extract individual item information using indexing. r(1) %% % Use concatenation of MATLAB list creation operations to extract multiple values. itmIDs = {r.ItemID} vals = [r.Value] %% Write to Multiple Items % Write to multiple items, passing the values for the items in the group as a cell array. write(grp, {1.234, 5.432}) %% % This particular example returns a warning, since the first item will not allow you to write data % to the item. However, the second item will have the value 5.432 written. r = read(itm2, 'device') %% Clean Up % Disconnect from the server and delete the client object. disconnect(da) delete(da) %% % Deleting the client object automatically deletes the group and item objects.