7i76 spindle setup

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12 Apr 2018 14:32 #108879 by PCW
Replied by PCW on topic 7i76 spindle setup
If I'm reading the manual correctly its should just work:

a) Hence if PB+ Terminal 7 remains open then a switch on PB- Terminal 8 can be used to change modes.

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12 Apr 2018 14:44 #108881 by Ross77
Replied by Ross77 on topic 7i76 spindle setup
I did'nt spot the truth table! Mark from Sprint has aslo confirmed it works that way and that using the spin out into pin 6 will also invert the signal ok.

Tho only question seems to be if i can use the enable and direction direct to the 340 as aparrently it is designed for push buttons so has 47k pull upp resisitors to the +12v line. will the optos be ok to pull that down or would it be safer to use relays?

Thanks for you help with this, getting there now.
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12 Apr 2018 15:17 #108883 by PCW
Replied by PCW on topic 7i76 spindle setup
The OPTOs are designed for this kind of service and will be faster and more reliable than relays

(relays typically don't do well with these low current (uA) signals)
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12 Apr 2018 23:38 #108921 by Ross77
Replied by Ross77 on topic 7i76 spindle setup
Thanks Peter. Works perfectly, full speed in both directions and runs at the comanded speed unlike the BoB i was using.

The only minor issue is that I seem to have lost the braking, when I was testing with just the pot and switches it was stopping really quickly. happy to have it working though so will leave that issue till later.

Im now haveing a few issues setting up the encoder. Is it ok to continue on this thread or should I start another one?

basically I couldnt get the index to work by using a TTL single ended sensor in any configration. Checked with halscope and nothing on the index only the Ach. I swapped them over to see if it was the sensor and still nothing.

Next I tried a 720ppr diifferential encoder (changed the jumpers) and again the A and B chaneels worked fine but no index. Halscope showed that it was being held high so i disconected one of the wires and it started working. have I wired it wrong or is there a problem with the card?

Ive hooked it up to the spindle and tested to 1000rpm and it seems work fine for rpm.
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13 Apr 2018 03:49 #108927 by PCW
Replied by PCW on topic 7i76 spindle setup
First, its quite difficult to check index on high resolution encoders without using index-enable
this is because at any normal speeds the index pulse will not be seen at the slow halscope
or even slower halmeter sampling rate. Second if a differential encoder starts working when you
remove one wire, this most likely means you have the 7I76 jumpered for TTL mode

To check differential encoder signals you measure across the A,/A B,/B and Z,/Z pins
if the absolute voltage _across_ the pins is ever less than about 2V in any state
(you have to move the encoder very slowly to get to all states) then encoder is likely wired incorrectly
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13 Apr 2018 20:25 #108966 by Ross77
Replied by Ross77 on topic 7i76 spindle setup
I couldnt even get it to work by turning it slowing by hand, I can see the logic signals on my probe but its not changing the state in hal meter. I did the same when it was running off the parra port and step config and could get it to show up fine.

I ve looked into the index enable an I will follow gnipsel.com/linuxcnc/tuning/encoder.html to test it over the weekend.

If the index is only used for threading could I just run a slow threading cycle and watch halscope?
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