... .NOTE:1, When ambient temperature is high or working current over 2.7A, fix the module on big metal shell , or ... not be damaged, but the electrical machinery runs abnormally, shake , and output is small.Please check whether the wiring of electrical machinery ... half current4,Pulse choice:In the driver has a jump5,installation dimension Stepping motor driver,1.3A-4.5A,high quality and reasonable price