3com 8814 Manuale Utente

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HAPTER

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AINTENANCE

Figure 62   Hyper Terminal serial interface attribute settings 

XModem is a file transfer protocol used for its simplicity and performance. It 
transmits files through serial interfaces, supporting 128 bytes and 1Kbytes in data 
units, checksum and CRC checking modes, and multiple transmissions attempts 
(usually 10 attempts) when packet errors are found.

XModem completes the transmission by the receiving program (receiver) and the 
sending program (sender). In XModem, the transmission begins by sending 
negotiation characters from the receiver for the purpose of check mode 
negotiation. After passing the negotiation, the sender is allowed to send the first 
data packet. Upon receiving the complete packet, the receiver checks the packet 
using the agreed upon check mode and sends an ACK if the packet has passed 
the check and a NAK if it did not. After receiving the ACK, the sender sends the 
next packet; if it receives a NAK, the sender retransmits the previously sent packet.

To run the Xmodem application:

1 In the Boot menu, type 4, press Enter, and the system accesses the serial interface 

submenu as follows:

SERIAL  SUBMENU

 

1. Download file to SDRAM through serial interface and boot

 

2. Download file to Flash through serial interface

 

3. Download file to HardDisk through serial interface

 

4. Modify serial interface boot parameter

 

0. Return to main menu

 

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