Hi,
Time to wake up and old thread... I still have this byte at serial port problem, and now I have very precise information about it... The problem is very reproductible. The Byte at serial port, in some circumstances, report the correct number, and in other conditions, it reports one more than is actually available.
When using the Modbus serial master query, with the following answer (in hex.), the reported number is correct :
01 06 00 05 0F FE 1D BB
When using the Modbus serial master query, with the following answer (in hex.), the reported number is incorrect :
01 06 00 05 0F FF DC 7B
The message is a request to write a single register (slave address 1, command 6, register 5, value 4095, the other bytes are the CRC). With other values than 4095, it works. Writing 4095 in other register addresses triggers the error also.
Don't hesitate to ask for any other information, should you need any more details.
Thanks,
Alex
