OPC deadband (location5)

Under the OPC standard, deadband processing is optional for servers. If the OPC server does not support deadband processing, the PI point is updated for all value changes to the point, depending on the exception attributes specified for the PI point.

Use a deadband to reduce the amount of network traffic from the OPC server to PI Interface for OPC DA. If the change between the last value read and the new value is less than the deadband, the OPC server does not send the value to the interface. For advise points, the location5 attribute specifies a deadband value for analog OPC items.

Note: Before attempting to configure advise points, be sure that your OPC server supports deadband processing.

OPC server deadband processing is not the same as exception deadband processing that takes place between the interface and Data Archive.

To configure the OPC server deadband, specify a percentage of the exception deadband range, multiplied by 100. OPC server deadband only applies to dwEUType analog items, which use the EU Low and EU High properties to calculate the range for the item. These OPC item properties correspond to the zero and span attributes in the PI point definition. For more information about OPC server deadband, refer to the OPC DA 2.05 specification.

For example, if the OPC server item is defined as analog with an EU Low of -10 and an EU High of 10, and location5 is set to 2500 (25%), data is sent to the interface only when the difference between the new value and the old value is at least 5 (25% of 20 = 5). Exception deadband processing continues to be applied to the values received by the interface. The OPC deadband attribute (location5) setting only affects the values sent by the OPC server.