Hi everyone, I’m using gSender to control a 3018 machine which uses grbl. I’m also using a standalone Arduino to control some auxiliary stuff manually, but I would like the Arduino to be able to listen in on the communication between the machine and gSender in order to respond to certain gcode commands (say, by turning off and on a fan). Is this something possible, or does the communication system preclude this arrangement?
Thanks
Hey Oriol,
You might be able to use a passive network tap, to listen into the tx communication between the pc and the machine. It’s pretty straigt forward to tap into the communication, but making word out of the signal may take some hard work.
Look into data sniffers and eth tapping for more detailed ideas.
@oriol How many things are you trying to control? Do you have a picture of or reference for your CNC controller? This may be a classic xy problem.
Assuming your proposed solution is the best solution, your best bet might be to use a USB -->serial converter on the PC side and connect the tx to both your CNC controller and Arduino Rx pins. You’ll also need to connect tx, +v, and gnd on the CNC controller. MCU grounds should be connected. To do this you’ll need to be able to bypass USB on the CNC controller.
Dealing with USB would be trickier.
I’m not sure what @Spamming_Eddie is getting at…he might be sniffing too much network data. 
neah, I was assuming an SLB with eth connection and tried to come up with a way to isolate a read only line based on that assumption. Revisiting the first post… never mind… me.
Neil’s ya man.
