H.E.S. 24NCS Lathe (24 X 60) conversion

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20 Apr 2015 03:27 #57910 by andypugh

Some of these seem obvious on where they should go but others I am not sure. Again I searched the forum but could not find an answer on how these should be wired. If someone could point me in the correct direction I would appreciate it.


The 7i76 manual says that to use a TTL encoder you set the jumpers:
"ENCODER INPUT MODE
The 7I76s high speed encoder input can be programmed for differential or single ended mode operation. W4, W5 and W6 set the encoder input mode. When W4,W5,and W6 are in the right hand position, the encoder input is mode is differential. When W4,W5, and W6 are in the left hand position, the encoder input mode is single ended or "TTL"."

I believe that you connect encoder A to ANCA+. You can look at the raw pin value with Halmeter. The A-channel is GPIO16. (I think) You should see it change as you rotate the encoder. (You should also see the encoder counts value change if A and B are correct)

Your HAL file seems to have the required encoder logic in it, so things ought to work as soon as the encoder is wired.

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20 Apr 2015 13:45 #57924 by canner
Ok, so here is my first stab at it:

1st I make sure the 7i76 is set up for single ended encoder input
2nd I will wire the following together:

Blue 0v goes to ground
Brown power supply goes to +5VP
Black OUTA goes to ENCA+
White OUTB goes to ENCB+
Orange OUT goes to IDX+ (Pin 13)
Shield Ground will connect into the main grounding bar

If this sounds right I will give it a shot tomorrow.

Thanks

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20 Apr 2015 16:07 #57927 by andypugh

Blue 0v goes to ground
Brown power supply goes to +5VP
Black OUTA goes to ENCA+
White OUTB goes to ENCB+
Orange OUT goes to IDX+ (Pin 13)
Shield Ground will connect into the main grounding bar


I found this in an old email:
"If the inputs are jumpered for TTL levels you must leave the -inputs
unconnected. The + inputs have 2K pullups to 5V so will be in a high state if
left open. "

So you seem to be correct.

I would source the encoder power from one of the protected (+5VP) pins on the TB3 terminal block, and the GND too.

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21 Apr 2015 11:53 #57961 by canner
Okay, not making any progress and think this is at the very least a major part of the problem. The encoder says it runs on 10-30 vdc, the power coming off of the 7i76 is 5 volts. Will it cause a problem if I route 24vdc power to the encoder but then run the A, B, and Z signals to the 7i76?


Thanks

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21 Apr 2015 12:09 #57962 by canner
The paperwork on the encoder says that the output is power supply voltage -4v on the high and 2 v on low. Will this be to much for the 7i76? I could probably also pull 10v off of the vfd, not sure if that would work but might be a solution without having to wire in another transformer. Any help is appreciated.

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21 Apr 2015 15:26 - 21 Apr 2015 15:38 #57966 by andypugh

The paperwork on the encoder says that the output is power supply voltage -4v on the high and 2 v on low. Will this be to much for the 7i76? I could probably also pull 10v off of the vfd, not sure if that would work but might be a solution without having to wire in another transformer. Any help is appreciated.


I don't know the answer to that question. I suspect that the only one who really knows is PCW.

Looking at the encoder data sheet it says that the encoder outputs are push-pull totem pole.
So, whether you can run the encoder at 10V or not depends on whether the encoder input pins are safe at more than 5V.
What are you using for Field IO voltage? 24V would be rather more common than 5V for limit switches and such.
Last edit: 21 Apr 2015 15:38 by andypugh.

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21 Apr 2015 20:03 #57968 by PCW
2V low will not work with the 7I76 inputs (they have a TTL input threshold = 1.6V)
What I would do is run the encoder from 24V then make a set of resistive dividers for A,B,Index
These dividers should be close to the 7I76 for noise immunity (that is most wiring should be done at the 24V level)

24V ENC SIGNAL --> 2K 1W resistor --> 7I76 encoder pin --> 390 Ohm 1/4W resistor --> ground

This is a approximate divide by 6 ratio so instead of 20V high and 2V low
you should get about .5V low and about 4V high
(offset somewhat higher than the divider output because of the 7I76s pullup resistors to 5V)

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22 Apr 2015 08:45 #57988 by canner
Thank you PCW very much.

So I went to Radio Shack this morning, seemed the only chance in this small town and looked at what they had for resistors. The closest I could come was 2.2k 1/2 watt for the signal ends and 333ohm 1/4 watt for the ground. I hope this is close enough. in the 1 watt size for the signals they only went up to 1k. If this will not work I will order the resistors online.

I only had time to solder in the resistors and check it out a little bit. With the resistors in and the spindle turning, I was getting about 4.5v on the signal wires. This is progress.

I went to the front of the machine and tried running a g33 and got nothing. I only had a few minutes to try looking for the signals with the hal meter and no luck. Not sure which I should be looking at but tried to find the pin 16 that Andy mentioned but could not, skipped from 15 I think to 17.

So possibly something in the hal file or wiring. I should have more time to look at this tomorrow. Any suggestions would be greatly appreciated. Thanks

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22 Apr 2015 16:36 #57995 by andypugh

I only had time to solder in the resistors and check it out a little bit. With the resistors in and the spindle turning, I was getting about 4.5v on the signal wires.


If you turn the spindle very slowly by hand you should see the voltage change from (about) 0V to (about) 5V.

The dmesg output should tell you which GPIO pin the encoder inputs are on, and you should be able to watch them in Halscope at low spindle RPM.

Also, if everything is working, you will see the spindle counts increase as the spindle turns.

If the counts are decreasing then that would explain why G33 isn't working, and you need to make the encoder scale factor negative.

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24 Apr 2015 08:19 #58059 by canner
Well, I got nowhere fast with the encoder. I checked the encoder with a meter, the hal meter, hal scope, an oscilloscope and was getting nowhere. It would help if I knew what I was doing with all of those :unsure: but the best I could tell there was a solid signal coming out that was equal on A, B, and Z no mater if the spindle was rotating or not. So I broke out a smaller encoder that I had originally purchased when I was planning on fixing the mpg's, sired it into the 7i76 and ran a test g33.

It worked, what great news. I feel comfortable saying something is wrong with the original encoder, I just don't know what. I will have to make a new adapter to connect it to the machine but that will not take to long. I should have the encoder bolted on and wired in tomorrow and then I need to start learning how to fully utilize the new abilities.

Thanks for all of the help so far

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