Similar to Hard Stop Homing, this is another proprietary feature of the SST servo drive that allows you to lower costs and increase system reliability within your machine by eliminating sensors, simplifying software procedures and reducing the need for mechanical alignments.
Limit Switch Homing allows you to home an axis with excellent precision by simply driving the axis into a limit switch at a moderate speed. This how it works:
Let’s say that you have an axis that is 100,000 counts long. You simply make a moderate speed move of 100,100 counts toward a limit switch. At some point during the move, the axis will contact the limit switch. At that point the SST will automatically ignore further pulses in that direction. Any pulses in the other direction (away from the limit switch) will be responded to as usual. So after the completion of the 100,100 count move, you simply command the axis to move away from the limit switch by a fixed amount to a precision home position. Using a narrow-aperture optical limit switch, the repeatability of this operation is typically a few micro-inches.
As you can see, this eliminates the cost of home sensors and eliminates the cost of hardware/software to process encoder signals for the homing operation. Software offset calibrations (for homing schemes that use an encoder index) are also eliminated. Because of this, the control software is greatly simplified, reducing development time.
The Limit Switch Homing feature (together with the RAS, Torque Fold-back modes, MoveDone output and flexible input resolution) helps enable the use of low cost controls, that lack encoder feedback inputs, even in machines that require state-of-the-art performance.