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SSI Interface

251

Encapsulation of RSM Commands/Responses over SSI

The SSI protocol allows the host to send a command that is variable in length up to 255 bytes. Although there is a

provision in the protocol to multi-packet commands from the host, the scanner does not support this. The host must

fragment packets using the provisions in the RSM protocol.

Command Structure

The expected positive response is SSI_MGMT_COMMAND which can be a multi-packet response. Devices that do

not support this command respond with the standard SSI_NAK.

Response Structure

Byte 7 6 5 4 3 2 1 0

0 Length (not including the checksum)

1 SSI_MGMT_COMMAND (0x80)

2 Message Source (4 - Host)

3 Reserved (0) Reserved (0) Reserved (0) Cont'd packet Retransmit

4 Payload data (see the following example)

...

Length -1

Length 2's complement checksum (MSB)

Length +1 2's complement checksum (LSB)