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Hi guys,

I'm thinking of buying the following 3-axis stepper motor kit from ebay.


I will not use the breakout board included in the kit but i wil use a Unitronics V350-35-TR34 instead.

My application requires simple, not very accurate positioning of 3 axes.

My questions are the following:

The driver accepts pulses of 5VDC while the PLC HSO is 24VDC. How can i convert the high frequency pulse to 5VDC?

Also the Pulses are NPN type. Is this a problem for the driver?

Thanks in advance

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  • MVP 2014

My brief comments as follows:

* the NPN outputs of the TR34 are an advantage when working with your 5V signal, as they will work with switching voltages as low as 3.5V (p4 of Spec Sheet)

* you will need a 5VDC supply (for example a regulated plugpack (what Australians call them) or "Wall-Wart??" (what the Americans call them))

* The wiring details for the stepper driver are a bit vague, but looks like the step and direction are opto-isolated. Assuming this is the case, put 5V direct from the supply to the (+5) terminals of the inputs, then wire the (-) terminal of each input to the PLC outputs, then connect PLC common to 0V of your supply (and link with 0V of your 24VDC PLC supply).

I hope this helps, and please note my assumptions.

You may be able to get more detail direct from the stepper suppliers own website.

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  • MVP 2014

I took a look at the installation guide for the JZ10-11-PT15. It's a bit of a grey area but I would suggest the following:

* the above specification that you quote (20.0-28.8VDC - which is 24VDC +/- 10%) relates to the power supply requirements for the output supply terminals at the right-hand end of the output terminal strip. This is the power required to drive the relays, and is the reference for the PNP solid state output.

* If you look at the wiring diagram for the NPN output, you can see that the above 24V supply is not referenced, and a separate "+Vnpn" supply is reference instead. This "+Vnpn" would be your auxiliary 5VDC, and also connect the 0V of the 5V supply to the 0V of your 24V supply.. The on-state voltage of the npn output is 0.4VDC, so it should work.

* note the lower frequency of the Jazz output compared to the V350-35-TR34, of 32kHz in NPN mode, when driving a resistive load.

As you can see there are a few maybes. If you want to be sure before purchasing the unit i would forward the question to your local supplier and/or to support@unitronics.com

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Thanks again for the feedback.

I was thinking of connecting a 2k/1w resistor in series with my PLC NPN output and connect it with the (-) pulse input terminal of the stepper drive.

Then connect +24VDC directly to the (+) pulse terminal of the drive.

The input is opto-isolated.

Should it work this way or not?

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  • MVP 2023

I have connected a stepper driver in exactly the way you describe and it works fine.

Let's look at the design specifics-

Your control specifies a 5V input pulse, which is extremely common. It has an internal resistor in series with the opto-coupler to limit the current to about 10 mA at 5V. As Simon mentioned, the on-state voltage drop of an NPN output is 0.4V, so we can effectively ignore it. The voltage the resistor will need to drop is 19V at 10 mA, resulting in a series resistor size of 1900 ohms, or the 2K you mention. The power rating of the resistor is 0.2W, so you really only need a 1/2W resistor.

If you can locate a 2K resistor, great. A 2.2K is much easier to come by and will result in slightly lower current through the opto-isolator but it will still work. This is the value I use.

Joe T.

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