View Full Version : What does active Hi and Lo do?

11-15-2005, 08:53 PM
What exactly does Active HI and Active Lo do? How does it alter the performance of the stepper. Can somebody please explain this stuff?

11-15-2005, 11:14 PM
those are two logic states, active lo means what ever it is referring to is active when the state is lo, hi just the opposite. Think of a light switch, when the switch is down and the light is on, the you could refer to it as active lo. If the switch is physically reversed so the paddle is up when the light is on, it could be referred to as active hi.

11-16-2005, 06:20 AM
Alright, and what do you mean by state is lo?

11-16-2005, 07:24 AM
TurboCNC gives the active low vs. active hi option in set up. I assume this is what you are curious about.
Active hi or low when switched in the "direction" check box will change the direction the motor turns; use this to make the motor move the table in the direction you want it to. This is easiest to notice when jogging, if the table moves in the opposite direction that you intended change the lo-hi setting.
Note: This is a handy feature for making mirror images of cuts, switch the lo-hi setting on the necessary axis and an identical but reversed pattern will be carved by the table.
The "step" active high or lo should be set according to the documentation that came with the driver, different drivers use diffo settings.

11-16-2005, 04:47 PM
in the sense you ave using active means true or on. If that light switch has a button down (lo) and the light is on, that equates to active lo. If the switch is up and the light is on that equates to active high. For a motor driver equipped with an enable signal. Active low when mean the motors will respond when the enable is lo. Active high means the motors will respond when the enable is hi. Your PC put out signals from your parallel port as two defined states, lo and hi.

11-17-2005, 01:21 AM
if low is defined as +5V then that is low...if high is defined at 0 volts then that is high....kinda depends on what High and Low are defined as....you might be dealing with 3.3 volt logic, CMOS logic, etc.