Re: how to synchronize 2 com ports

This question is well-applied for Richard Grier :)
Seen your web page, seems like you are very keen on that...
I am looking for a protocol which I want it to be full-duplex
One side I put a timer, about one timer event per 1 second.
Then the receiving end must consume the data. On the receiving end, which is
a SBC, it also sends commands continuously (also one second between pulses),
now the sending side has reversed role and becomes the receiving end, this
data acquisition unit consumes the command and sends full data back to the
SBC.
So two cases, the data acquisiton end sends data either if
* there is some data on it received from sensor array
* the SBC asks for it and the DAQ might send or telling the SBC there is no
data to be consumed
Sometimes the data is discarded or the data read cycle is prolonged
depending on the situation
one situation is
* The shutter is closed when some data in transit. Then the read cycle is
prolonged until all data has been received
* The shutter is closed, then some data is going to the SBC end, the SBC
relinquishes (oh i like this word, if I spell it correctly) it.

This is what I've got from my colleague. I am half-finished the program and
I am stuck at the protocol.


Thanks
Jack

"Jack" <jl@xxxxxxxxxx> ׫??ì¶à]¼þÐÂÂ?:%238uBmyNmGHA.2112@xxxxxxxxxxxxxxxxxxxxxxx
Hi,
I am sending a variable length data from com3 to com4
sometimes just !q and sometimes it is #m123456
sometimes !q is followed by !s etc
but the receiving end sometimes reports
!q!
then next one is
s
So after the shift
#m123456
became
m123456
which could not be recognized as proper data on the receiving end
How do I synchronize these 2 ports?
I have set MSComm to Handshake = XonOff
all buffers set to 1024
and inputlen = 0
RTSEnabled
DTSDisabled
Baudrate = 460800bps thru USB bridge
CTS Output flow control checked...
Thanks
Jack



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