Carrol Touch TouchSystems CarrollTouch Prog, Programmer'S Manual, Page: 73 / 274

Chapter 5 - Smart-Frame Protocol II CARROLL TOUCH
5-16 Touch System Programmer’s Guide
no report. At this point, there are 14 bytes in the input buffer, with 18
bytes remaining.
If the host repeats the timeout and re-send cycle three more times, the
input buffer overflows when the third command is sent, and the touch
system responds with the following report:
E0 06 FE 20 01 04 03 FF 66 04 20 01 04 03 FF 66
04 20 01 04 03 FF 66 04 20 01 04 03 FF 66 04 20
01 FF
FE
is the Cmderr parameter and indicates that a byte count mismatch
error occurred. The following 30 bytes echo the command number and
parameters that the touch system received before the input buffer
overflowed. The touch system is now looking for a new command, and
if the host sent the command once more, the touch system would
receive it, process it, and return a report (presuming no error occurred
in sending this latest command).
The time to re-synchronize this entire sequence would be a little over
four seconds - the original command timeout (one second) plus three
retry timeouts (one second each). The fourth retry would not result in a
timeout because the touch system would send the report that contained
the bytes read.
The host need not wait for enough timeout and re-send cycles to fill the
input buffer, however. The host can accelerate re-synchronization by
issuing enough FFH bytes to flush the touch system’s input buffer. This
forces the input buffer to overflow and causes the touch system to begin
looking for a new command. For example, if the host had used this
method after the first report timeout had occurred, the touch system
would have responded with the following report:
E0 06 FE 20 01 04 03 FF FF FF FF FF FF FF FF FF
FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
FF FF
FE
is Cmderr and indicates that a byte count mismatch error occurred.
The following 30 bytes echo the command number and parameters, as
well as the flushing
FFH
s that the touch system received before the
input buffer overflowed. The touch system is now looking for a new
command, and if the host sent the command once more, the touch
system would receive and process it, and return a report (presuming no
error occurred in sending this latest command). With this approach, the
time to re-sync is a little over one second (the timeout for only the
original command).