Start signal not detected

Getting the message with arduino with ramps 1.4. I downloaded the latest marlin and installed. Tried all the baud rated. Update runs clean. I've tried a couple of different boards and get the same thing. Set to Com 1. Should I be able to get past this it the board is out of the printer and just hooked to the USB. I'm just trying to find out what other debug steps I can take. 


  • Yes, a naked board with firmware should still connect. It might complain defect sensors if not connected, but at least you should see it. If you use 115200 baud you should even be able to connect with arduino ide serial monitor and see the default message at startup. Hit reset button to show it again.

    If you can update firmware the communication it self must work. In host make sure that protocol is ascii or autodetect, binary will not work with marlin.
  • set both ascii and auto with same result. Using windows 10. loaded marlin 1.8.8 and drivers from ide 1.8.8, shows as version . get ascii response in Repitier log and Arduino ascii monitor when I press the start button. also Tx polling light after connect. also shows connected PRUSA in status line. any other testing options? thanks.
  • If it shows connected and you see the ascii response it should be good. Send e.g. M119 to query firmware and see if you get a list of status in log (expert mode required).
  •  I used the serial monitor just a little to verify an output from the stop button on the ramps. How do you enter expert mode. I have 1.8.8 installed, and haven't found doc on it yet, I did a search on their site, but ran into issues with the search function. Thanks. 
  • In host click on Easy button. Then you see you can enable log and in manual commands there is a text field to enter commands.
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