Navigation:  Spectrometers > OPC client

OPC is an international standard for the exchange of information between machines (what is OPC?). An OPC client object in the list of spectrometers is able to connect to an OPC server and read and write values. You can use OPC client objects to respond to an external signal, e.g. to trigger a measurement action, or to pass information about fit parameter values or the current position of a traverse system.

 

The OPC client window (select the client in the list of spectrometers and click on Edit to open it) looks like this:

 

 

The drop down box at the top of the window lets you select an OPC server. If the server runs on a separate computer you have to specify the computer in the edit box on the left. Once the server is selected you can connect by a click on the chain symbol. The connection will be announced in the text box on the left side.

 

Use the Add items button to select server items. Selected server items are watched by the client at an update rate that you can specify in the lower right corner of the window. Value changes are indicated in the text box to the right.

 

When you save the program configuration OPC client objects save the names of the selected items. After loading a configuration that contains selected OPC server items, SCOUT reconstructs the items when it re-connects to the server.

 

OPC items may have quite long names which are difficult to remember. You can define a nickname for the first selected item. The nickname can be used in optical functions (see below).

 

Optical functions

Using the names of selected OPC server items or the nickname for the first selected item you can retrieve the current values of the items as optical functions. The items must deliver a numerical value, of course. Here is an example of optical functions:

 

 

Script commands

OPC client objects execute the following script commands:

 

•object command, my opc client, connect                 (connect to the selected server, start listening)

•object command, my opc client, stop listening         (stop listening to the server)

•object command, my opc client, pause listening       (stop listening to the server)

•object command, my opc client, continue listening    (continue listening to the server after a pause)

•object command, my opc client, send integer, server item name, value    (sends the specified integer number to a server item)