I have a CNC sand table with an UNO running GRBL. It works great using Universal GCode Sender to stream GCode to it.
For demo purposes, I would like to have a separate Nano reading GCode files from an SD card and streaming them to the UNO. I can read a file from the SD card and send the contents to the serial monitor easily enough (there's an SD example that does exactly that), but I can't figure out how to send the GCode from the Nano to the UNO. I tried hooking up RX>TX and TX>RX and just running the dump example, but that didn't work.
I've read about different kinds of handshaking - and I think GRBL sends an OK message after each line - but I'm not sure how to get started. I think I need to read line by line from the file, send one line at a time, and wait for the response from GRBL before sending the next one, but I'm not sure. Could someone give me an idea of what I need to do to make this work? Thanks!