While not "garbage"
  read
end-while

Or in other words,

On each read, check for "garbage".
If "garbage" found, re-read until OK.

Or is it hard to automaticly detect what's "garbage" ?

Jan-Erik S=F6derholm.

-----Original Message-----
From: Francois Robbertze [mailto:fr10@mweb.co.za]
Sent: den 11 september 2002 20:17
To: PICLIST@MITVMA.MIT.EDU
Subject: [PIC]: RS232 & PIC


I have a PIC between a RS232 and a RS485 that only check & calculates =
CRC values and respond to only few commands (e.g. Error Status and =
Firmware Version). All the other data is just passed on to the slaves =
on the RS485 network together with the CRC value.=20
If I power up the board...the fist data request to the firmware or to =
any other slave on the RS485 network returns "garbage". The follow-up =
request is always correct (Just very little CRC errors on slaves that =
are very far from the master unit - acceptable)

I expect the problem to be at the return data of the RS232 because the =
PIC respond to the commands the first time. If the CRC value is not =
correct or the PIC received "garbage" then it would just return to =
standby and the computer will retry.

I compensate for this by reading the firmware version from the PIC =
every time the software on the computer starts. The PIC or RS232 =
returns "garbage" (which I dont display) and after that the system =
works fine. I have a problem when the master unit is switched on when =
the software is already running.

Any suggestions?

Francois

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