The stepper driver is likely monitoring the output current, so it might not work as expected when driving an external switch. Steppers need to change the voltage supplied as the motor speeds up in order to maintain the current.

 

The stepper driver is likely monitoring the output current, so it might not work as expected when driving an external switch. Steppers need to change the voltage supplied as the motor speeds up in order to maintain the current.

That had crossed my mind initially, but it just seems that the stepper is maintaining a position?

The motor will not be under constant use, more like a few steps at a time for position correction.

 

Yes just a few steps every once in a while. No constant RPM operation at all.
It just turns a focuser (on a telescope) as the temperature changes.

 

So you do not really need PWM etc, just simple step/direction control at the plate rated Voltage/current.

 

The provided stepper output is from a DB9 connector.
Here is the pinout for that connector.....

1 Phase A / Digital out
2 Phase B / Digital out
3 Phase A' / Digital out
4 Phase B' / Digital out
5 +12 V D.C.
6 Input (not used for the moment)
7 Input (not used for the moment)
8 V+s (for the external temperature sensor - LM60/LM61)
9 Vout from the LM60/LM61

Shell Ground

 

So you do not really need PWM etc, just simple step/direction control at the plate rated Voltage/current.

Yes
It's not a constant direction or RPM etc.
It's just a nudge probably a few steps to turn the focuser. The problem is that the controller box only provides a maximum of 1 amp out and the stepper I want to use needs 1.68 amp per pulse.

 

My bipolar stepper motor wiring.

 

There is still the problem that the controller might might misbehave if it is not sensing the expected current.

 

What is the voltage rating for the stepper windings?

 

Electrical Specification:

* Manufacturer Part Number: 17HS19-1684S-PG5
* Motor Type: Bipolar Stepper
* Step Angle: 0.35 deg. (it has a 5:1 gear reducer)
* Holding Torque: 2Nm
* Rated Current/phase: 1.68A
* Phase Resistance: 1.65ohms
* Inductance: 2.8mH+/-20%(1KHz)

Rated Voltage/Phase 2.8 VDC

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