Stop Motion Sensing Unit. Power requirements-the SR125SMS45 will accept 24 VDC or 110 VAC. Motion detection input-the SR125SMS45 detects the stop condition of all types of AC or DC motors by sensing the motor’s back EMF across terminals Z1, Z2 and Z3. Drive compatible-the SR125SMS45 will function with electronic motor control devices such as variable speed controllers, DC injection brakes, etc.. Selectable speed limit-the SR125SMS45 has 1 N/O and 1 N/C outputs that are switched when motor speed reaches the adjustable preset limit (0.01 to 0.10 V) for the particular output. Auxiliary output-the SR125SMS45 has 2 solid state auxiliary signaling outputs.