Message formats

The data area of SSI messages has the following general structure (the specific structure is dealt with under the individual messages):

length Parameter
2 bytes Length specifying the number of subsequent bytes in this message.
1 byte The SSI ID (equals 21H for all SSI messages)
5 bytes Source address (comprising region number, component number, module, value number, subaddress, each 1 byte)
2 bytes Message status bits (see 3.2)
2 bytes Data status bits (see 3.3)
1 byte Data format (message type)
1 byte Data type (there is a data-type/data-format assignment table for each project)

A list of the SSI message types supported by the driver follows. Most message types can be set in both the message and the command direction. Different peripheral addresses must be specified for the message and command direction.