Labview RS232 ASCII protocol

[garyjm]

Hi,

I am designing a PLC based system that will provide data (via a RS232 serial link) to a LabVIEW system. Can anyone help me with information on the ASCII character string that I need to construct.

Does the data I am providing need an ASCII header and footer? If so then which of the ASCII commands do I need to provide?

Thanks for any help

Gary

[chembo]

I have seen implementations using ASCII code 0x02 (STX; start of text) as first character of the transmission and 0x03 (ETX; end of text) as a very last character.

Some other implementations send initially the length of the message, for example the first and the second characters, i.e. bytes, indicate the number of characters to expect.

If you need to make sure that there are no errors during transmission, you may need to use some kind of checksum. There are a lot of possibilities. I guess it depends on the type of data, as well as other requirements. There are some examples in LabVIEW too.

[K C]

Since it is a PLC maybe it is ModBus ASCii ??

Kees