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Stepper motor control with UID-0808THS

Mark P

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I’m working on a Unistream application using UID-0808THS modules to control stepper motors on an XY table. I have the moves working and the machine sequences through the preset positions but I have an issue with homing.

The homing function woks fine, when initiated to set the current position to zero, or whatever offset is used, but I need someway to move the motors to a position that is the home position, or an offset from the home position, before initiating the home function.

This could be a programmed sequence that goes to a switch input, or a manual jog type function that would allow the operator to move the table manually and then set the home position when it is in the correct position. I can’t find any way to get the motors to move other than the relative or absolute moves on the PTO Move function.

Any help or suggestions would be appreciated.



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  • MVP 2023

In general, I imagined the process of moving to the home position as follows.
1. Configure the axis as in the PTO example for jog mode - that is, slow movement from an external signal (Go home bit) for a distance greater than the length of the linear axis.
2. Check whether the home position sensor is activated.
3. If so, move in the opposite direction until the sensor is turned off and then move in the this direction for some time (or distance) - "Retract from home sensor" mode
4. If the sensor is not activated (or the movement described in point 3 is performed) - set the intermediate variable - Go home bit  movement to the home position ( slow Jog move to home sensor used).
5. With the help of this bit, we activate the jog movement towards the home position. This bit is deactivated by the home sensor signal. At the same time, a quick stop of movement to the home position is activated.
6. After a complete stop (velocity =0 or after some time) - the intermediate home position is established by the PTO command for define HOME.
7. Next, the position movement (absolute or increment again configured) is carried out by some value defined by the parameter in the opposite direction from the home sensor in order to move away from it.
8. After stopping this movement, the PTO command for setting the zero position is activated again and only then I can say that the mechanism is in the home position. (Home sensor now can be used as End Sw).

P.S. Maybe someone use different sequense - than please post used solution to this topic

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Thanks, Item 1 in your reply was the most important, after looking at the jog example it made everything easier. Once i could jog the motors the homing sequence is pretty simple, and I have used one of the existing over travel switches. A bit more testing to do but seems to be working fine.  

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  • 6 months later...

Hello, friends
I'm new in stepper motor control and decide to use  Unistream PLC with UID-0808THS.I have some questions, maybe stupid but i want to clear the concept according t Unilogic Software and PTO function:

1. According to the hardware UID-0808THS i want to use high speed ouptputs for Pulse + Direction this means O0 and O1 wih CM2 as common. I cannot understand but CM2 is internal minus for HSO or not ??? As i understand O0 and O1 are coresponding to Bock 1 of the module  in Unilogic Hardware Settings ???

2. According to base settings of PTO function:


The manual is not so clear.  If i put Pulse ration of 1 and units ratio to 1. Velocity should be maximum volume of pulses on witch motor should work or a maximum working frequency. I cannot understand clearly....

4. Phisicaly how i can know what to put to minimum and maximum velocity, i don't have experiance with such kind of motors and i cannot understand the point. This is my combination of motor and driver:

Driver: https://cnczavod.ru/uploads/docs/Leadshine/drayver-dm860h-manual.pdf
Motor: https://exallto.com/motori/164-stpkov-motor-nema-34.html

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