Micrologix 1400 and NPN Strepper motor

Mray · Sep 6, 2019

Hi there,

I wanna run Micrologix 1400 L32BXB which has PNP type PTO to a stepper motor with NPN driver (JB542M).
So, should I buy PNP to NPN convertor or is not necessary?

Also, I have problem with Pulse+/- and Direction+/- connection to PLC. For only one direction and just for test, Can I connect Direction+ directly to 5VDC or I have to use a separate PTO for direction?

Tnx

Mray · Sep 12, 2019

No help!

Please advise me how o solve this issue.

kolyur · Sep 12, 2019

It might be possible to make this work if the step and direction inputs on the stepper drive have independent commons. You could fake an NPN output from the Micrologix by connecting the PTO output (OUT2 for example) to the +V common on the drive, and the common for that group (COM2) to the step input which would also be -24V. The disadvantages of this setup would be (1) it renders the other outputs 3-7 in the group useless, and (2) if the step and direction inputs on the drive have a shared common, you wouldn't be able to control the direction.

It isn't necessary to control the direction signal from a PTO output; it could be regular transistor or even relay output depending on how often you intend to change direction.

Another problem is your voltage difference. You mentioned 5V but the PLC operates on 24V. You may need current limiting resistors to keep from frying the drive.

Mray · Sep 12, 2019

kolyur said:
It might be possible to make this work if the step and direction inputs on the stepper drive have independent commons. You could fake an NPN output from the Micrologix by connecting the PTO output (OUT2 for example) to the +V common on the drive, and the common for that group (COM2) to the step input which would also be -24V. The disadvantages of this setup would be (1) it renders the other outputs 3-7 in the group useless, and (2) if the step and direction inputs on the drive have a shared common, you wouldn't be able to control the direction.

It isn't necessary to control the direction signal from a PTO output; it could be regular transistor or even relay output depending on how often you intend to change direction.

Another problem is your voltage difference. You mentioned 5V but the PLC operates on 24V. You may need current limiting resistors to keep from frying the drive.

Tnx for your reply.
I use current limiting resistors as well.

My first question is what if I don't want to change the direction, how I can do wiring in the simplest way?
Second, how I should connect the PNP/NPN convertor to the PLC and stepper motor? I attached a photo of my convertor.

Caveman · Sep 13, 2019

My guess is you are going to need
Part no. 8324610000 relay
Part no. 8389030000 end plate
Mfg. Weidmuller
Description MiniConditioner MCZ 0 24vdc/5 VTTL

This is a high speed opto coupler.

I was going to get some, just didn’t get around to it.

Mray · Sep 13, 2019

Caveman said:
My guess is you are going to need
Part no. 8324610000 relay
Part no. 8389030000 end plate
Mfg. Weidmuller
Description MiniConditioner MCZ 0 24vdc/5 VTTL

This is a high speed opto coupler.

I was going to get some, just didn’t get around to it.

I use resistor for dropping voltage from 24 to 5 v.
It should be OK, yes?

Micrologix 1400 and NPN Strepper motor

Mray

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