Fast Inputs with PLCopen Motion

For PLCopenA vendor -and product- independent worldwide association active in Industrial Control and aiming at standardizing PLC file formats based on XML, refer to MC_TouchProbe, which arms a Fast InputThe inputs are taken into account at each cycle depending on the system periodicity (for example each millisecond). Under certain circumstances this can be insufficient when more accuracy is needed, or if a quick response is required from the system. To fill the gap, a drive may have some Fast Input connections (generally one or two). When an event happens that triggers a Fast Input (e.g. when a sensor sends a rising edge), the detection of a signal occurs faster (which can be 1000 times more accurate than the system periodicity). Then the timestamp associated with this input can be provided to the IPC to take corrective action and returns the latched position when the Fast Input event occurs.

Other PLCopen function blocks which arm a Fast Input and return the latched position to the function block when the event occurs are shown below.

Registration operation	Homing operation
MC_MachRegist MC_MarkRegist	MC_Reference MCFB_StepAbsSwitchFastInput MCFB_StepLimitSwitchFastInput

Table 7-2: PLCopen function blocks which arm Fast Inputs and return the latched position.