Reducing 24V output to 5V for FM Stepdrive

aaaaaa understand, what about connect grounds together from this 5V power supply and that FM? Nothing else goes within my head. But pls check again my idea...

Edit: because you're using signal from external power source to another device. Am I right?

I obviously did this, I connected the GND input from pulse interface (on the left side) with the 5V source's ground.

I'm wondering what are the "_N" ended signals on the right side of the interface, I mean "PULSE_N", "DIR_N" and "ENABLE_N". There's nothing about them in the manual. Does anyone know what are they for?

Hello, probably these are Negative signals, I think.

Edit: reverse?

hmmm I'm affraid that if you want drive some servo motor, you can use some SW simulation. Is this your situation?

Edit: with static signals it will work ok I think...

hello,

did you look at this?

https://cache.industry.siemens.com/dl/files/051/1118051/att_23930/v1/FM_Stepdrive_A0101_e.pdf

Page 12.

Update2: also page 13 is important.

What do you mean by SW simulation? Software simulation? I have my stepper motor connected, all signals on the side of PLC work properly, when I turn on online mode in TIA Portal I can see them switching and everything is good. The problem must be located on the side on FM Stepdrive or, possibly, my circuit. The module works properly, possible causes can occur only in pulse interface because other "parts" of module seem to work perfectly.

Edit: I've seen this manual, I connected everything according to the schemes I found there.

I triplicated my circuit (one per every pulse interface input, they only have common 5V supply) and to every one (circuit) I connected one output from PLC. Otput from every circuit is then connected to proper input in pulse interface. I supply ENABLE with static signal, PULSE with 10Hz and DIR is not supplied (so the motor can turn clockwise). I also supply inputs in signal interface - ENABLE_N and GATE_N with 24V. Everything else is connected according to the manual (FM supply with 230V, motor phases connected to U, V, W etc.)

I think it's not the question of bad wiring, I would figure it out on my own. I guess there's the problem with 5V signal because when I supply only ENABLE input (in pulse interface), without ENABLE_N (in signal interface) the RDY led doesn't light. The manual says that it's enough to supply one of them to get the READY signal so it is a proof that my 5V signals are not received by the FM Stepdrive.

Originally the FM device was connected with positioning module e.g. FM353 which controls the pulse interface with 5V signals. It was necessary for older controllers like S7-200 or S7-300. I need to connect the FM device directly to S7-1500 PLC so have to "reduce" the output voltage from PLC to 5V - that's why I'm using that optocoupler circuit.

/Offtopic/

Thnx for perfect explanation. It was very interesting to me from your first post to see, that you need make some own solution to this. Will look to this topic to see conclusion, but will also try discover something helpfull to you. Thnx.

Thank you for your answers and advices! When I finally figure out how to run this motor using FM Stepdrive I will describe it here.

Unfortunately the problem is still not solved. I'm working on it but still look for advices.