The 8909U is a simple and compact DIN-rail mounted stepper motor driver for use with 5, 6 or 8-lead hybrid stepper motors. A Xilinx FPGA device is used to control the phase excitation of each motor under the control of STEP and DIRECTION signals from the 8601. Additionally, the AUX1 output of the 8601 on each channel can be used to control the power ON/OFF function of each drive channel. A green status indicator LED shows the active status of the card as follows:

 

The driving outputs of this card are compatible with all four-phase hybrid stepper motors with 5, 6 or 8 leads. These motors typically have two pairs of windings, each with ‘driven’ connections and ‘common’ connections. In 6-lead motors, the centre-point of each pair is brought out as this common connection. The ‘driven’ or phase leads of the motor should be connected to the PHASE (A to D) outputs of the card and the ‘common’ or centre-tap lines connected either directly to the motor supply voltage at terminals 2 and 5, in the case of motors with windings rated at the full supply voltage, or through high power series current limiting resistors in the case of motors with lower winding voltage ratings.

The limit switch inputs on this card are compatible with voltage-free contacts from micro-switches or the transistor outputs of opto switches. The wetting current of these inputs at 0.4 volts is 0.5mA. All these inputs are conditioned and opto-isolated before being sent to the 8601. The assumed function of these switch inputs is ‘Normally Closed’, meaning that an open condition indicates travel beyond the limit. If limit switches are not used in a system, the positive and negative travel limit switch inputs should be strapped to ground. The ‘Home’ limit switch input is only used in systems where the software function ‘go to home limit’ will be used. It therefore has no function and can be left open in systems where just the two travel limits are used.