I need to connect an arduino to step driver. But I need to generate a step & direction or step & step and it needs to be connected to modbus. but it needs to be compatible with mach3
have a look at
https://www.cooking-hacks.com/documentation/tutorials/modbus-module-shield-tutorial-for-arduino-raspberry-pi-intel-galileo/
butt i thought abought some thing like this
butt it doesnt talk how to generate the step & direction