Mesa 7i96S - Delta B3 drive differential connection

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15 Dec 2022 09:22 - 15 Dec 2022 09:26 #259546 by routerman22
Hi,

I'm looking at connecting the Delta B3 drive to my mesa 7i96s.
When I look in the documentation it seems that the differential output lines on the 7i96s are 5v ttl.
In the documentation of the delta drive it says: 2.8 - 3.6V systems only. I can't seem to find the actual max values for this input.
filecenter.deltaww.com/Products/download...3_UM_EN_20210201.pdf


Edit:
For the Other drives I Have the delta-M , this is 5V for the differential line input:

So it seems I only need this for one of the drives.
Last edit: 15 Dec 2022 09:26 by routerman22.

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15 Dec 2022 09:41 - 15 Dec 2022 11:32 #259548 by routerman22
I'm going to ask delta what the max voltage input for the differential line input is.

In this post it seems to work normally with 5V differential input:
forum.linuxcnc.org/38-general-linuxcnc-q...sa-7i95-delta-asd-b3
Last edit: 15 Dec 2022 11:32 by routerman22.

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15 Dec 2022 11:50 #259551 by tommylight
Adding a 68 Ohm resistor to each input should be good fir 5V.
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15 Dec 2022 11:56 #259552 by routerman22
Looking at the image it looks indeed to be an optocoupler input. And adding extra series resistors to match the current rating for the LED should suffice.

I'm a little bit disappointed that delta has so little info about it in the datasheet as such drawings don't always match the hardware.

Thank you for the info!
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15 Dec 2022 16:15 #259562 by PCW
Actually you may not need any external resistor as the differential output
impedance of the 7I96S step/dir outputs is about 80 Ohms.

This gives about 21mA LED current: (5-~1.1V LED drop)/182 Ohms
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16 Dec 2022 11:09 #259624 by routerman22
I got the drive today. Suprisingly it is super easy to open it.
Input seems to have PTC fuse -> clamping diodes -> optocoupler.
Optocoupler seems to be:
docs.broadcom.com/doc/AV02-0470EN

It can handle up to 50mA forward current for the led,
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