code: function checkDeviceValue() {
      		debug('Checking Device Value');
      		self.iRead(context.register)
      		.then(function(res) {
      			var val = res.val;
      			var sandbox = {
      				'x': val,
      			};
      			var scriptContext = new vm.createContext(sandbox);
      			var result = context.script.runInContext(scriptContext);
      			if(result) {
      				reportResult(res, result, 'resolve');
      			} else {
      				performRetry(res, result);
      			}
      		}, function(err) {
      			errorLog('Error...', err);
      		});
      	}
docs: This function performs the actual device I/O and runs the user's eval string to check the result.