3Com 3C17539 Installation Manual page 88

88 C 6: S M M
HAPTER WITCH ONITORING AND AINTENANCE
Figure 62 Hyper Terminal serial interface attribute settings
Upgrading software XModem is a file transfer protocol used for its simplicity and performance. It
through console port transmits files through serial interfaces, supporting 128 bytes and 1Kbytes in data
(XModem) 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
Enter your choice(0-4):4