Modifying serial communication parameters – H3C Technologies H3C WX3000E Series Wireless Switches User Manual
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Enter your choice(0-3):
Upgrading the software through a serial connection
by using XMODEM
To upgrade the BootWare and system software image file through a serial connection, use the XMODEM
protocol.
XMODEM is a file transfer protocol that is widely applied because of its simplicity and good
performance. XMODEM transfers files through serial ports. It supports two types of data packets (128
bytes and 1 KB), two check methods (general checksum and CRC), and error packet retransmission
mechanism (generally the maximum number of transmission attempts is 10).
The XMODEM transmission procedure is completed by the cooperation of a receiving program and a
sending program. The receiving program sends a negotiation packet to negotiate the packet check
method. After the negotiation, the sending program starts to send data packets. When receiving a
complete packet, the receiving program checks the packet using the agreed method.
•
If the check succeeds, the receiving program sends an acknowledgement (ACK) character and the
sending program proceeds to send another packet.
•
If the check fails, the receiving program sends a negative acknowledgement (NAK) character and
the sending program retransmits the packet.
Modifying serial communication parameters
Sometimes, a high serial port baud rate is needed to save the upgrade time, or a lower baud rate to
ensure the transmission reliability. This section describes how to adjust the serial communication baud
rate.
1.
Enter the BootWare main menu, select 2 to enter the serial submenu, and then select 5 to modify
the baud rate.
The system displays the following information:
=================================
|Note:'*'indicates the current baudrate |
| Change The HyperTerminal's Baudrate Accordingly |
|---------------------------
|<1> 9600(Default)* |
|<2> 19200 |
|<3> 38400 |
|<4> 57600 |
|<5> 115200 |
|<0> Exit |
===========================================================================
Enter your choice(0-5):
2.
Select an appropriate downloading rate. If you want an 115200 bps download rate, for example,
enter 5.
The system displays the following information:
Baudrate has been changed to 115200 bps.
Please change the terminal's baudrate to 115200 bps, press ENTER when ready.