TwinCAT 3 Motion Control (Part 2): PLCopen Motion Function Blocks Explained

In part 2, we continue the discussion on motion control in TwinCAT 3, focusing on programmatic axis control using the PLCopen-compliant Tc2_MC2 library. It explains how to link the PLC to the NC axis and introduces the Axis_Ref data type, which serves as the interface between the PLC and the NC. We will also review the axis operational state diagram and details essential function blocks from the Tc2_MC2 library, such as: MC_Power for enabling the axis MC_Reset for fault clearance MC_SetPosition for setting the axis position MC_MoveAbsolute and MC_MoveRelative for precise movements MC_MoveVelocity for continuous travel MC_Stop and MC_Halt for stopping axis motion In the second half of the tutorial, I provide a practical demonstration of implementing these function blocks in a TwinCAT PLC project. I will show you how to add the Tc2_MC2 library, instantiate an axis using Axis_Ref, and link it to the NC axis. The demonstration includes enabling and disabling the axis, executing absolute and relative moves, using the set position command, and controlling continuous motion with MC_MoveVelocity, followed by stopping the axis using MC_Halt and MC_Stop. Finally, I'll demonstrate how to clear axis faults using MC_Reset. Also check out part 3 of the motion tutorial, where I will cover integrating an actual drive and motor.