Retrofitting a 3-axis VMC with DC servos - guidance needed

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28 Jul 2026 10:38 #348123 by Japoo_Ness
I'm having some trouble with the servo enable relays.My relays have flyback diodes, but the datasheet is giving me a headache. The coil draws 40mA, but the flyback module includes an LED with no specified current draw. Since I can't be sure of the total load, I'm guessing I can't use it.Would you guys just change the module for these specific commands, or is there a better workaround?

These are the Finder 55 Series

i think its better to use other relays for these ones like interface relays isnt?
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28 Jul 2026 10:43 - 28 Jul 2026 10:46 #348124 by Japoo_Ness
If it takes all this just to run the enable signal, I'm thinking it's better to wire it directly to the drive. Is there any good reason to keep it isolated with an extra relay? The 7i97T outputs are already opto-isolated, and my servo drive has a 10kΩ input impedance anyway. Adding a relay isn't really worth it, right?
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Last edit: 28 Jul 2026 10:46 by Japoo_Ness.

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28 Jul 2026 13:24 #348134 by PCW
The 7I97T enable outputs should be able to drive that directly.

If you worry, you can always measure the current with a DVM
 
The following user(s) said Thank You: Japoo_Ness

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21 Aug 2026 11:00 #348898 by Japoo_Ness
Thanks, i use new relays to keep that separation and use the old ones to the tool changer (not automatic, but to grip the tool holder i dont know how its his name in english) and another auxiliary, but i want to keep the 7i74 and 7i73 to the future in the end, I will use the 7i84u connected by the port in 7i97t.
Looking at the pins in it using the standar bin it will recognize the 7i84, now i have the bin of the 7i97t & 7i74 i will be a problem or its better to upload the standar?
And the configuration to connect the board its ussing this no?
 
Again, thanks for all the help.
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21 Aug 2026 14:09 #348904 by PCW
If you use 7i97t_7i74d.bin firmware,  sserial channel 0 is on the 7I97T and
sserial channels 1..7 are on the 7I74.  (Physical channel 0 is skipped on the 7I74)

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01 Sep 2026 20:51 #349193 by Japoo_Ness
Perfect, ty so much.
I have a problem with the 7i84u.
In the datasheet mention W1 y W3
But apear W4.
What this do?

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01 Sep 2026 21:31 #349199 by PCW
Currently unused

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