I would like to see a worked example of a printf command being sent using this command as its not clear from the documentation.
It would be great if someone documented the endianess of the data types but I've been assuming little endian and this seems to work.
My problem is with this one command
echo is a 4 byte little endian uint = 1U
pad0is a 4 byte little endian uint = 0U
reserved is a 4*7 byte zero filled array
nLength is a 4 byte little endian uint = 256U, the size of the fixed array, if you make it anything else it causes a syntax error
szStr[256] is a 256 byte array containing the null terminated ASCII format string. No matter what command I put in here, nothing happens. I would like to see some string command which has been proven to work both as a readable string and an ascii array.
I still think that if it is in the same variable, it should only have one entry.
My code is in C# .NET8 not C++/C so I can't use the header files.
It is not "the same variable". You're projecting your lack of understanding of the difference between C/C++, which this interface is expressed in, and C#, whcih you chose to use, into a supposed deficiency of the documentation. There is none. You're just misunderstanding it because your're reading it in a different language than the one it's written in.