public function getEmployeeIdByKey($cardNumber)
    {
        $cardNumber = $this->prepareKey($cardNumber);
        $result     = null;
        $this->addHeader();
        try {
            $soapResult = $this->getSoap()->GetAssignedAcsKeyByKeyNumber([
                'keyNumber' => $cardNumber
            ]);
            if (isset($soapResult->GetAssignedAcsKeyByKeyNumberResult->AcsEmployeeId)) {
                $result = $soapResult->GetAssignedAcsKeyByKeyNumberResult->AcsEmployeeId;
            }
        } catch (\SoapFault $ex) {
            $this->logError();
        }

        return $result;
    }