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From: D Yuniskis on 5 Jun 2010 14:53
D Yuniskis wrote:
> I suspect I may have left a hole unplugged someplace. But,
> just these few things (all of which are trivial to implement)
> would allow the "other device" to converse with the device
> in question without fear of: something being "missed" *or*
> something being "misinterpreted".

<grrrr> You also *effectively* need a NO-OP message that
can be used as a keep-alive/link test. With many devices,
you can often find some "benign" command that you can
repeatedly invoke -- solely for the *acknowledgement*.
E.g.,
"BAUDATE 19200"
"ACK-BAUD3"
"BAUDRATE 19200"
"ACK-BAUD3"
"BAUDRATE 19200"
....

And, of course, you have to make sure the interface activity
doesn't *unreasonably* interfere with the normal operation of
the device. I.e., if changing the baudrate caused a barcode
scanner to misread a label that was being scanned concurrently,
you'd have a hard time justifying (to me) why that should be the
case! :-/

(OTOH, I can understand that a UPC label that is being decoded
may or may *not* be recognized if a configuration command
enabling/disabling recognition of UPC labels was acted upon
concurrently)
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