Fanuc retrofit retaining original AC servo motors and drives

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11 Apr 2019 14:11 #130661 by Todd Zuercher
What voltages are your GPIO signals? Most of the Fanuc machine I've worked with are running 24v io. A 7i50 is only 5v. I think some of Mesa's Smart Serial daughter cards may be a better option.

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11 Apr 2019 14:52 - 11 Apr 2019 14:53 #130667 by PCW
To interface to the the Digital Fanuc motor drives requires

1. 2 analog inputs per channel (2 phase current feedback channels)
2. 8+ TTL level or differential signals (depending on drive model)
6(TTL) or 12 (Differential) of these signals are the three phase PWM
which must reverse direction based on the driver ready signal,
as they are used for fault signaling when the drive is not ready
3. The host (linuxCNC) or a smart controller must implement commutation and FOC

This may be something better done with a STMBL drive with no power circuit
or a custom FPGA card with the correct I/O built on board
Last edit: 11 Apr 2019 14:53 by PCW.

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11 Apr 2019 15:21 #130672 by mclausen
PCW:
I am switching to Fanuc A06B-6050 analog servo drives. Should I be able to drive these from a 7i48?

Todd:
Thanks, I hadn't looked at that whole section of cards. I assume I just need a 7i44 RS422 daughter card to talk to them?
Yes, the Fanuc I/O is 24 volt, but I was planning to use opto-isolators to interface to the 5 volt. The serial cards will simplify that.

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11 Apr 2019 19:44 #130691 by PCW
Yes, a 7I48 will work, another option is (instead of 7I48+7I44)
7I52 for 6 encoder input and
6 Sserial channels:
--> 7I83 for analog
--> 7I84 or 7I84D for digital

This has the advantage of isolation of the analog outputs

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11 Apr 2019 21:00 #130694 by mclausen
Thanks. That looks like a good option. There is no speed performance problem with sending all the analog commands through serial?

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11 Apr 2019 21:02 #130695 by PCW
No, there are no significant delays with sserial (at least relative to 1 to 4 KHz servo thread)

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