Bill,

>......  It is posible to manually type in the commands.
>If you are watching what comes over the line, you can understand it.

Absolutly true. But how about the little ram-space in a PIC, let's say a
16C71. If you send a command in text, even if it's a little one, I don't
think you have enough ram to store it before decoding?? And I hope I'm wrong....

> Having a message length field is great, but
>if the receiver gets thaoses bytes garbled, then he may think the message
>is an extremly large one, and spend our lifetime just receiving the
>"last message".

Thrue, I would expect the same happing if the end-mark is garbled? Maybe
putting in an extra checksum for the header data??? ;-)

>Does the slave request at what intervals he wants to be polled?
Yeah, that's the idea. It does it's request when acknowledging a command. I
mine opinion, a slave should never start to talk when not adressed.

I do agree that the slave can't trow away VITAL data if it doesn't know
wheter the master has received it. So the master has to acknowledge this
reception. This ackowledge can also be the request for the next data-packet
or a request for resend (STATUS BYTE 2, bit2=1) when transferring an array.

>The network I have described does not handle vital information.  If
>something goes wrong, then the one or more logs are lost and the
>daily report of the loged data has a glitch.  If people's lives or
>money were involved, then much more would need to be done to insure
>safety.

Can't agree more with you.

An other question. Multi-master mode. I'm a little bit confused about this
term. I would expect that this is a situation where a number of slaves are
being controlled by more than 1 master (why?). Or are we speaking about this
mode because a slave becomes a master when it's talking???

Edwin
Edwin Baaij  (Electronic Engineer)
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