Xmodem overview, Modifying serial port parameters – H3C Technologies H3C LSWM1WCM10 Access Controller Module User Manual

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Upgrading BootWare and applications through a

serial port

NOTE:

The LSWM1WCM10 and LSWM1WCM20 do not provide console ports to support upgrading BootWare
and application programs through a serial port (console port).

XMODEM overview

To upgrade the BootWare through a serial port, use the XMODEM protocol.
XMODEM is a file transfer protocol that is widely used due to its simplicity and good performance.

XMODEM transfers files via serial ports. It supports two types of data packets (128 bytes and 1 KB), two

check methods (checksum and CRC), and error packet retransmission mechanism (generally the
maximum number of retransmission attempts is ten).
The XMODEM transmission procedure is completed by the cooperation of a receiving program and a

sending program. The receiving program sends a negotiation character to negotiate a check method.

After the negotiation, the sending program starts to send data packets. Upon receiving a complete

packet, the receiving program checks the packet using the agreed method.

If the check succeeds, the receiving program sends an ACK character and the sending program
proceeds to send the next packet.

If the check fails, the receiving program sends a NAK character and the sending program
retransmits the packet.

Modifying serial port parameters

To save the upgrade time, a high serial port baud rate is preferred; to ensure the transmission reliability,

the baud rate needs to be reduced. This section describes how to change the serial port baud rate.
Enter the BootWare main menu and select 2 to enter the serial port submenu. Then, select 5 in the

submenu. The system displays the following:

=================================<BAUDRATE SET>===========================

|Note:'*'indicates the current baudrate |

| Change The HyperTerminal's Baudrate Accordingly |

|---------------------------<Baudrate Avaliable>------------------------- |

|<1> 9600(Default)* |

|<2> 19200 |

|<3> 38400 |

|<4> 57600 |

|<5> 115200 |

|<0> Exit |

==========================================================================

Enter your choice(0-5):

Select an appropriate baud rate. For example, select 5 for 115200 bps. The following information
appears:

Baudrate has been changed to 115200 bps.

Please change the terminal's baudrate to 115200 bps, press ENTER when ready.

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