Unit 5: Printer Configuration
The block number starts from 1, and when counting to 255, the number goes back to 0 again. If the block number is [01h], complement of block number becomes [FEh]. In the main data, the section of data by 128 bytes is stored. SUM is the check sum computed from 128 bytes of main data.
NOTE: The above method is XMODEM (check sum) option. Select check sum option in the XMODEM settings on the host side.
When downloading data, the format is such that the first 16 bytes are used as header information and the rest is considerred as data. The header information is divided thusly: code (4 bytes), start address (4 bytes), file size (4 bytes), and reserved area (4 bytes). The remaining optional data is to be stored in Flash ROM.
The basic sequence of XMODEM is to transfer data blocks by individually checking response blocks. NAK (15h) transmission by the receiving end initiates the sequence, and the sending end sends the first data block after receiving NAK. The receiving end receives and checks this data block, and then returns ACK (06h) in case of no error or NAK (15h) in case of an error. The sending end sends the next block when receiving ACK, and resends the same block when receiving NAK. This process repeats to the first block. EOT (04h) is sent from the sending end to receiving end at the end of all data transmission. After receiving EOT (04h), the receiving end returns ACK to terminate the sequence.
SATO MB2i Service Manual | PN 9001145B | Page |