Servos/ encoders/ drives???

[Ark1]

I am trying with my background as an electrician to comprehend the complexities of assembling my own control for a CNC Mill conversion.

It appears that every time I go forward I go two steps backward.

My goal is to convert my TOS FN20 Milling machine to CNC control. I want to make a complete set of drawings with wire numbers, first to understand the concept of what must be done and then to have drawings to trouble shoot from.

In a post written by Diyengineer, Al Stated that the motor leads were red and black with the other lead being ground. I tested my motors 72 V with a 12 volt car battery and found that the red and the yellow caused the motor to turn. The black appears to be ground. The encoders AMT 102 show a pin out ( see pictures) with the black being ground and the green being the index output. ( have no ideal what the means.) As an electrician the ground standard is green for ground, but what I am seeing is that may not be the case. Also when going through the manuals for the Rodgers board, Sound Logic Break out board and the Geckodrive 320x drives each wants a bench test. Then there is Mach 3 ( have purchased licence) which has a whole set of parameters to be completed with no power to the drives or motors. Is there a guide somewhere that is inclusive of the above, or have I thought of what I want, purchased it all only to find that to assemble it I should do it as a progression rather than an all in one installation?

I really don't want to fry anything. But at times I find myself going in circles.


So first off, have a look at my pictures, I think Black is ground on the AMT 102 encoder and black is ground on the servos.

Any comments are most welcome.


Thanks.

Ark1 ( TonyK)

[Al_The_Man]

Very simple to test which is motor power and ground with a DC motor as the DC should not be referenced to ground, the conductor that shows continuity to the motor frame will be the ground.
With encoders, the power and common as a general rule is Red and Black, in this case it is black not green as the DC common may not be at ground potential.
Unfortunately they tend to use the term Ground when common is implied, which can be misleading.
The index or marker pulse on an encoder is a once per rev pulse output which is usually used as a home reference marker on closed loop systems. Usually not used with Mach.
With the encoders you have the data sheet to go by.
I just looked at your encoder sheet again and it looks like they did not use standard wire colours, go by the pin out.
If you are an Electrician you have a head start on the Electrics.
Al.

[Ark1]

Originally Posted by Al_The_Man Very simple to test which is motor power and ground with a DC motor as the DC should not be referenced to ground, the conductor that shows continuity to the motor frame will be the ground. With encoders, the power and common as a general rule is Red and Black, in this case it is black not green as the DC common may not be at ground potential. Unfortunately they tend to use the term Ground when common is implied, which can be misleading. The index or marker pulse on an encoder is a once per rev pulse output which is usually used as a home reference marker on closed loop systems. Usually not used with Mach. With the encoders you have the data sheet to go by. I just looked at your encoder sheet again and it looks like they did not use standard wire colours, go by the pin out. If you are an Electrician you have a head start on the Electrics. Al.

Okay you have confirmed what I have been testing as I go. But here is where it gets just a bit fuzzy again. This is a new venue for me. I understand the concept of star ground or multipoint ground. Now here is the next question. The Antek Power suppy I purchased is 75 volt and has also a 5 volt and a 12 volt supply. The 12 volt supply will drive 2 cooling fans anytime the the power supply is on. The 5 volt supply could be used for the encoders, but both the DRO Rodgers board and the Sound Logic ( SLB )break out boards have 5 volt supplies.

The encoders first terminate at the DRO board and then out to the 320X Drive for encoder inputs. The SLB provides Step and direction and it has a 5 volt supply as well. The manual states not to connect the commons as I can see Kerchoff's law applying. (And loss of isolation,) Which states the direction of the poles of an electro magnet. What I am trying to say if the commons are connected depending on the polaity of the coil and the AC supply to the board the sum of the transformers could be additive and present 10 volts or buck and produce a circulating current and zero volts.

As you stated I am an electrician, but that brings forth a lot of theory that can hamper my thought process.

Back at the boards, by just connecting each wire on 2 boards present a problem? Even though both boards have their own 5 volt supply. Or, should I be looking at using the Antek 5 volt supply? And some how abandoning the 2 boards 5 volt supply. I am back to being an apprentice asking a lot of questions after doing a lot of reading.

Just learning. Thanks Al.

Ark1 ( TonyK)

[Al_The_Man]

If you use a separate 5v supply for the encoders, there should be no problem of connecting the encoder common to the eventual destination point common.
If the encoder input point can supply the 5v at the desired current then this may be the preferred way.
There are two schools of thought, the originators of BOB's state to Isolate all systems, I happen to use the alternate method of making systems common to each by way of their supply commons, this I would connect to the earth ground point.
If I use opto isolators, it is usually to transfer from one voltage level to another, e.g. 5v to 24v etc.