>Strtofile gave me sometimes "File is in use by another proccess" sometimes in this scenario. TEXT...ENDTEXT too.

I haven't had problems with this approach:

c="text to append to the log file, terminated with a crlf"
strtofile(lcLog, c, 1)

This basically appends the line(s) to the logfile and is very fast, because you aren't writing the whole file, you're doing an equivalent of fopen(), fseek() to the end of file, fwrite(), fclose() - all in a single call. The file is busy for a very short time. And you can trap the error (if it ever happens) in a try/catch and try again a dozen milliseconds later.