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Drive a Gecko Stepper Drive from UID-0808THS


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Hi 

 

I am trying to drive a Gecko Stepper Drive from a UNISTREAM PLC I have the UID 0808-THS (PTO) module and the Gecko drive already so I am to some degree committed to these components.

 

The issue is that the Gecko only works with a 5V input and my understanding is the PLC only outputs 24V? is this correct or when you configure the system to run as a PTO it switch to a NPN type contact with no Voltage?

image.png.dfe4983a59cc55371f0b4886924eddea.png

 

Does the OUTPUT O0 and O1 turn into a NPN type connection that can have its own power supply or will they still produce a 24V PTO signal when activated?

 

image.png.363f4114475c778bc1971bc90c1e5084.png

 

I have looked at Transistors and MOSFETS but all seem to drive the other way Lower Voltage to Higher not Higher voltage to lower voltage.

 

Any help would be greatly appreciated.

 

Only other thought was a simple voltage divider of (O0) 360ohm ^ 90ohm (CM2) tapped in the middle to produce a 5V signal (metal oxide so I can dissipate 5W) but my raw electronics is a bit rusty to test on system.

 

Any help, or advice would be greatly appreciated.


Thanks in advance.

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The UID  0808-THS spec says it's PNP, because they are transistors they cannot be "switched"

Usually the best way to handle voltage variations is to use NPN hardware such as the UIS-WCB1 and an NPN gecko driver so you can tie the 0v together and have it function, next best option I would look at would be to use a high speed opto-coupler depending on how fast/accurate you actually NEED to drive the gecko, a lot of those stepper drives have "micro-step" settings where you can change the step/pulse ratio to lower your accuracy but also reduce the necessary pulse frequency.

This one says it has a max conversion of 20khz, you would also need a 5v PSU but those are cheap.

 

-Swervomotor

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19 minutes ago, kratmel said:

Yeah I have seen this and was wondering if the PTO Output handle the resistance:

 

image.thumb.png.5c71f1fa2be2000bae3613c593f2cfc3.png

 

But I assume this mean I can use O1 to drive the high resistance? or is this a range for these output? Is this indicating that the higher load increases the turn off time?

 

Cheers

 

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  • MVP 2021

What they're showing on the Gecko document kratmel pointed out is there is an internal opto-coupler in the Gecko drive designed to run with 5V pulses.  The formula they give indicates it will draw 16 mA, so you have to drop the rest of the 24V PLC output across the 1.2K resistor.

The switching times on the table you show indicate there is some internal capacitance on the output of the PTO module and it takes a short time to discharge it when you go to the OFF state.  Higher resistance = more time.

You can emulate the input resistance of the Gecko drive by dividing the 5V design signal by the current in the equation, or R = 5 / .016 = 312 ohms.  So if you connect the PTO module to the drive with a 1.2K resistor in series the total load seen will be about 1.5K.

You should be fine.

Joe T.

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