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USC-3 Manual > Interfaces and Signals > Stepper I/Os

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The USC card has 3 TTL stepper inputs Stepper_In_0..2 and 6 TTL stepper outputs Stepper_Out_0..5 on the Stepper - 10 pin connector.

Unlike the Opto I/Os, Laser_Gate, Laser_A and Laser_B the Stepper I/Os are not optical isolated from the USC main power circuit.

 

Stepper_In input levels:

•The voltage on Stepper_In_0..2 may not exceed +24 V in respect to GND.

•The input level of Stepper_In signals in respect to GND:

olow: between 0 V and UTh - 1 V

ohigh: between UTh + 1 V and 24 V

▪By default, the input threshold for activation of Stepper_Ins UTh is around 2.0 V. This threshold can be increased by the use of an appropriate external resistor RExt must be added. Calculate the value of the resistor with the following formula:
 

 

Stepper_Out output levels:

•The output levels and max. currents are listed in chapter Electrical Characteristics.

warning

During USC-3 startup and when the laser signals are disabled by software, the Stepper_Outs will go into tri-state. It must be assured that the connected device defaults to a safe operation in this case. Potentially, a pull-up or pull-down resistor (about 4k7 ohm) has to be added to put the connected device into a safe state.