Carrol Touch TouchSystems CarrollTouch Prog, Руководство программиста, Страница: 66 / 274

CARROLL TOUCH Chapter 5 - Smart-Frame Protocol II
Touch System Programmer’s Guide 5-9
parameters of the SFP-II command packet that solicited
the report were valid.
If the command number and parameters were all valid,
this parameter is 0.
If there was an error associated with one of the command
parameters, this parameter contains a number that points
to the first byte of the parameter that was in error. If there
are multiple parameters with errors, only the first one is
indicated.
If the command number is invalid, this parameter is FFH.
If no SFP-II command packet was associated with this
report (i.e, the report is an unsolicited report), this
parameter is 0. Refer to “Error Reporting,” later in this
chapter, for more information on this parameter.
reportnumber
= One byte opcode that identifies the SFP-II report. Valid
opcodes are 00H through BFH.
optionalreportparameters
= Parameters for the SFP-II report. The maximum number
of parameter bytes is 251 (FBH).
trailer=
Defined to be FFH.
The maximum length of an SFP-II report packet is 256 bytes.
The generic report format for SFP-II reports reflects the fact that SFP-II
is a layered protocol. There are two layers, the validation layer and the
interpretation layer.
Validation Layer
The format for SFP-II reports at the validation layer is as follows:
header packetbytecount interpretationlayer
trailer
Note that the validation layer consists of the outer portions of the report
format and “wraps” around the inner portions of the format, or the
interpretation layer. To detect a valid SFP-II report in the incoming
stream of bytes, the host must detect the header, read the byte count that