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Asynchronous
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  • OPC I/O Servers supports two different methods of obtaining data: Synchronous and Asynchronous I/O.


  • In typical OPC client, this selection updates items at regular intervals.


  • Asynchronous I/O, by comparison, does not enable the OPC Client to poll the server; it provides data between the driver and the OPC server on an exception basis.

  • Using Asynchronous I/O, the server notifies the OPC Client when data has exceeded the user-supplied percent deadband.

  • This architecture offers low communications overhead because the driver does not repeatedly poll for the same data over and over again.

  • Information that is not synchronized to a continuously running clock. With asynchronous transmission, each character begins with a 'start' bit and ends with a 'stop' bit and the clock is only synchronized for the duration of the character.


    • See also Synchronous.


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    GPS (Global Positioning System) ../ Duplexer ../ Cyclical Redundancy Check ../ DOX (Data Operated Transmit) ../ Hot Standby ../ Response Time ../ I/O (Input/Output) ../ GHz (Gigahertz) ../ Half Duplex ../ DigiBoard ../ Carrier Sense ../ Thermocouple T-Type ../ VSTO - What is it? ../ Thermocouple - How do I choose a Type? ../ Asynchronous ../ Datablock or Poll Record ../ RS-232 ../ HART ../ PTT (Push To Talk) ../ VHF (Very High Frequency) ../ See More..
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