如何检测打印机是否联机

GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, 0);
     if (h == INVALID_HANDLE_VALUE){
     AfxMessageBox("Can not open lpt1");
     return false;
     }
     t.ReadIntervalTimeout = 0;
     t.ReadTotalTimeoutMultiplier = 0;
     t.ReadTotalTimeoutConstant = 0;
     t.WriteTotalTimeoutMultiplier = timeout * 1000 / prtlen;
     t.WriteTotalTimeoutConstant = 0;
     if (!SetCommTimeouts(h,&t)){
     AfxMessageBox("SetCommTimeout error");
     return false;
     }
     result = true;
     if (!WriteFile(h,prtdata,prtlen,&n,NULL)){
     AfxMessageBox("Print error");
     result = false;
     }
     CloseHandle(h);
     return result;
    } 

关键词：如何检测打印机是否联机