Exceptions and Error Handling

Exceptions

In the event of an error, the WinCC OA JavaScript Manager for Node.js always throws an exception. If this exception is not handled in the code, the manager terminates with a Fatal error. To prevent the manager from terminating, the exception can (and should) be caught in a try/catch block.

Exception Handling of the WinCC OA JavaScript Manager for Node.js

// import WinCC OA interface
import { WinccoaManager } from 'winccoa-manager';
const winccoa = new WinccoaManager();

// main function
async function main() {
  const dpeName = 'ExampleDP_Arg1.';

  try {
    const value = await winccoa.dpGet(dpeName);
    console.info('Node.js® manager for WinCC OA working');
    console.info('Value of ' + dpeName + ' = ' + value);
  } catch (exc) {
    console.error(exc);
  }

  winccoa.exit(0);
}

// start the main function
main();

Error Class

The WinCC OA JavaScript Manager for Node.js provides the class WinccoaError, which can be used to obtain additional details about occurred errors. You can find an example of its use and information on which details are available in the API documentation: WinccoaError

All error codes generated in the WinCC OA JavaScript Manager for Node.js which don't have a directly corresponding error code in WinCC OA are enumerated in WinccoaErrorCode. They are explained in detail in the API documentation: WinccoaErrorCode