Wiring a Chinese servo to a 7i77. Setup for yet another newbie

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15 Oct 2019 20:21 #147943 by bevins

tommylight wrote:

SPH wrote: TB3 PIN FUNCTION DIR

1 QA0 TO 7I77 PA+ pin 20
2 /QA0 TO 7I77 PA- pin19
3 GND FROM 7I77 GND pin 1
4 QB0 TO 7I77 PB+ pin 18
5 /QB0 TO 7I77 PB- pin 17
6 +5V FROM 7I77 do not connect
7 IDX0 TO 7I77 do not connect
8 /IDX0 TO 7I77 do not connect

Also +-10V from Mesa to pin 25 and 13 respectively .
Drive enable from Mesa to pin 29 and 9.

\
Why are you not connecting the index of the encoders?

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15 Oct 2019 20:35 #147946 by SPH
Let me know how the index connects and I’ll wire it in. Perhaps tommylight’s directions were just the basics?

The drive enable is so obvious now, thanks. Don’t know what was thinking.

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15 Oct 2019 21:11 #147947 by tommylight
Just checked it again, did not notice that there is a normal output for Z (index) AND an open collector output, saw only open collector that evening, sorry my bad. Anyway i was trying to make it simple for him, due to open collector requiring resistors to be added and different wiring needs.
Back to it, the Z or index pins are 15 for enc+ and 16 for enc-.

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16 Oct 2019 00:31 #147961 by bevins

SPH wrote: Let me know how the index connects and I’ll wire it in. Perhaps tommylight’s directions were just the basics?

The drive enable is so obvious now, thanks. Don’t know what was thinking.


How did you wire the enable pins?

Also make sure you have the correct motor selected in the programming. I am still looking for my parameter sheet. It is in a backup and I haven't located it yet.

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17 Oct 2019 01:05 #148068 by SPH
I haven't wired the enable yet, still trying to get some idea how its supposed to work using a DMM. It looks like I should be sending pin 9 which is the positive supply from the drive to ENAN+ on the 7i77 and then ENAN- to pin 6 on the drive which is SRVON.
I assumed I'd be able to pick up a 12 or 24v signal from the drive though between pin 9 and ground but so far no luck so I'm still a bit lost as to what's going on.

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17 Oct 2019 03:18 #148069 by PCW
The 7I77 drive enable pins (ENAN+ and ENAN-) are just a floating switch

Its usually a good idea to verify that you can enable /disable
the drive with a mechanical switch before wiring to the 7I77

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17 Oct 2019 05:37 #148071 by SPH
Thats what I figured too. I thought I should be able to just bridge pins 6 and 9 on the drive and get it to enable. I'm away for a few days so I'll dig back into it when I get home

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17 Oct 2019 07:56 - 17 Oct 2019 07:57 #148090 by bevins
What I do is connect outputs to machine-is-on. That way relays get energized and I use the contacts to enable the drives, Its easy to blow those outputs, just ask me how I know. This way it is bullet proof.
Last edit: 17 Oct 2019 07:57 by bevins.

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20 Oct 2019 09:34 #148393 by SPH
I sorted it out. Nothing too complicated as usual, in hindsight.
The drive needs external +24v power for it's inputs, DC+ on pin 9 and DC- switched on pin 6 for enable.
External 24v+ to TB5 pin 2, 24v+ switched from TB5 pin 1 to pin 6 on the drive. 24- to pin 6 on the drive.
Enable now works and soft estop also works as expected. I'll get a hard estop working next.

There's about 1/8 of a shaft rotation just as the drive enables. Perhaps something to do with the fairly high rpm drift when the loop isn't closed? Should I be chasing drive parameters to tone this down or is it something in software? I imagine it'll make for a pretty good mechanical 'clunk' when everything connected for real.

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22 Oct 2019 06:26 #148528 by SPH
I've got the X and Z axis' wired and running. Jogging is acceptable.
I take it the tuning will be influenced by the actual mechanics of the machine so I shouldn't get too far into the tuning until the servos are actually mounted?

I'll also have the fun job of re-wiring my encoder and motor plugs as I somewhat foolishly decided to use the existing motor cables from the Yaskawas to save a buck. Should'a just spend the buck. The motor cables are easy of course, just the 4 wires. It's the 15 pin encoder cables I'm not too keen on.

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