"David" <firstname.lastname@example.org> wrote in message <email@example.com>... > "Ken " <firstname.lastname@example.org> wrote in message <email@example.com>... > > Im trying to output a HEX string to a camera to makes it turn a filter on. The command is '8101040102FF'. I've made a small m.file to do it. When i run the m.file the filter doesnt turn on. > > Im not sure if the HEX string is being output ftom the m.file to the com port because nothing happens. > > > > code > > > > s=serial('COM1'); > > set(s,'BaudRate', 9600); > > set(s,'DataBits', 8); > > set(s,'StopBits', 1); > > fopen(s); > > Str=('8101040102FF'); > > sprintf('%s %X','8101040102FF') > > fclose(s); > > your sprintf statement is malformed. you have 2 substitutions, %s and %X but only one value which is a string. > > and are you sure the camera wants the digits as a string, or does it want them as binary bytes?