I need a book!

[jimc]

How to wire servos for dummies! I have read and looked at this screen till my eyes hurt at users manuals etc etc., and I still don't know where to start. I have Advanced Motion Amps, a galil controller, a power source and regular brushed electrocraft servos.

The controller is a dmc 2040 for 4 axes, with an ICBM 2900 hooked to it that has spots for 104 wires to run 4 servos or 104 ICBM's. Each amp has terminals for 21 wires plus 4 pots and it seems like between the two of them they should control most everything but the toilet lid.

I assume the "-motor" and "+ motor" go to the servo motor and the "+ref in" and "-ref" in go to the controller. Then I guess the "high voltage" is the + side coming in from the power source. But does the other side of the power source go directly to the other side of the servos?

I presume the encoder wiring goes directly to and from the controller.

Any thoughts on this would be greatly appreciated.

Thanks.

jimc

[Al_The_Man]

You have just about everything right, the ref+- are the command signal from the Galil, the encoder does go back direct (via the ICM).
The DC power source should go to the two marked Power+ and power GND.
Do NOT take the DC power direct to the servo.
The servo is fed as you say from the + Motor - Motor.
AMC also have the whole hook up on their Engineering Notes site.
http://www.a-m-c.com/download/docume.../instnotes.pdf
Once hooked up, you should be able to control the servo with the DOS or Window DOSterm or Talk2bus programs from Galil.
Al.

[jimc]

Thanks a million, Al. When the amp wasn't labeled "Power in +" "Power in -"
I got confused. I don't want to cook something. I'll look on the Engineering notes to see if I can tell if it makes a difference which "Power Gnd" I hook the power supply to since there are two of them right next to each other.

Being a carpenter turned pretend machinist, with a memory about as long as a, well we won't talk about that.

Thanks again,
Jimc

[Al_The_Man]

What PS did you use or did you build one? The term power Gnd is becaus if the power supply AC side is not grounded, you have the option of grounding the negative side of the power supply, this would go to the AMC Power Gnd or PS -ve. But it is not mandatory.
To test the encoder, If you connect the encoder up, without powering up the AMC power, you should be able to turn the shaft of the motor and using the DMCterm program, repeatedly do a TP (tell position) and you should see the encoder counts go up or down with rotation.
The green light on the AMC should be on when you do eventually apply power to it, if the enable input is correct.
Al.

[jimc]

Al,
I bought the Power supply (and all the other stuff) off ebay and the AC power to it is grounded to the strap that holds the giant capacitor. But I powered it up and it has 60 volts which is what these motors take. It has a bridge rectifier with a resistor or something soldered across the two posts that are not parallel with each other.

I just noticed something else too. The encoder has 5 terminals arranged like this:

1) Gnd
2) index
3) Channel A
4) 5 volt
5) Channel B

The connector that goes to it has only 4 wires. If I put the green wire on #1) Gnd, I am missing a connection for #4) 5 volt.

If I put the black wire on #1) Gnd, I am missing a wire for #2) Index. Something tells me this is probably not a good way to do it, and that I should add a wire.

I will try what you just said if I can fiqure out where the other 4 wires go on the controller.

Thanks, Al.

[Al_The_Man]

You need all 5 connections from encoder to Galil, The one marked Gnd is actually 5v common.
In reality the better encoders have 8 connections, as the A,B & Index have dual outputs, this is called a differential encoder, it is less prone to noise interference, you will notice the Galil has input allowance for these.
But these types will work also.
Al.

[jimc]

All right AL! You the MAN!

[jimc]

In reality the better encoders have 8 connections, as the A,B & Index have dual outputs, this is called a differential encoder, it is less prone to noise interference, you will notice the Galil has input allowance for these.

My three new encoders from US Digital arrived today. The ones with 8 wires. All my machines are so noisy I need earmuffs myself, so I decided to take your advice and get the better ones. I needed some more anyhow.

I mounted up one of the servos to a slide after I made an adaptor plate so I could get it on there solid. I downloaded the free software off the galil site and got the servo to move the slide. It took me forever to get the slide to stop where it was supposed to despite messing with the KI, KP and KD. Finally, I realized that I should have been typing the changes into the little screen instead of the big screen. For a while there, I thought that part of the controller was broken.

I learned one thing about the controller. If you type in "TP" and the number of counts instead of "PR" and the number of counts, and hit "enter" the slide moves in the OPPOSITE direction than it does when you type in the right command. Fortunately, I had plenty of experience screwing up when I built my other tapping machine that uses a PLC, so I didn't tighten the shaft couplings but just barely.

I didn't have that option on my other machine, and wound the lead screw up into the nut past the threads and it was so tight I had to take a 4" pipe wrench, clamps and cheater bars to get it out of there.

Has anyone ever used the software that Galil sells for their controllers? I'm not sure whether it is just for tuning the servos or if it's supposed to be an easier way to do the programming too. If it's just for tuning - I won't bother with it, but if it will be easier to learn how to program the motion with it, I will go ahead and buy it.

Well thanks again for the help, Al. I was just kidding about the ear muffs.

Regards,
Jimc

[Al_The_Man]

Has anyone ever used the software that Galil sells for their controllers? I'm not sure whether it is just for tuning the servos or if it's supposed to be an easier way to do the programming too. If it's just for tuning -

Galil do not have much, other than the DMCTerm for running program in native code, the tuning program and the DXF to Galil converter.
Al.

[jimc]

Thanks, Al. That’s what I thought. I guess I’ll just hold off then and tune the servos by trial and error once I get the table, fixture, and all the other stuff built. It’s not like I’m going to be doing anything fancy anyhow. All this thing has to do is tap 4 holes in the same size flat plates over and over again. But I probably won’t be able to get everything done until this fall. I’m hoping that the galil controller will be able to sense current. Then I would not need anything special when I get to work on an automatic screw driver. It would be nice if the controller could sense a cross threaded screw by a jump in current, because then it could back out the screw and reject the part. I still have a bunch of reading to do on that thing.

It didn’t take very long to get the one servo working once I started typing into the right screen. Even when I tell it to go at speed, acceleration and decelleration of 9,999,999 it stops right where its supposed to. Course I’m trusting that it’s not lying to me because I havent put an indicator there to check it at that speed.

But at more reasonable speeds when it goes in the minus direction it goes a little past then comes back immediately. I don’t know if that is right or not. But all the growling noises are gone from the motor, and it is very smooth. I guess the test will be if it gets hot when I get the whole thing together and running for prolonged periods.

Well thanks again for the help, Al. When I get the thing up and running, I’ll take a short video and stick it up on my website in case anyone is interested.

Regards,
Jimc

[Al_The_Man]

It should not overshoot if properly tuned, I have found you can position to ±1 encoder count (TE).
It sounds like you could have also used a Galil stand alone system, I have used these with a Maple Systems interface for a MMI.
I also use an obsolete piece of software that Galil dropped when the PCI bus came out, it will only work with Galil Legacy ISA cards, but it is an amazingly useful piece if S/W, operator screens can be written in just a few minutes, I have used it on & off for about 15yrs on different projects, they are all still running, all in an industrial environments.
Al.

[jimc]

That's the kind I have, a stand alone black box made of 16 ga steel. Good and rugged. I really havent even counted up the inputs and outputs yet or checked out how to set "triggers' to iniate motion, but I have a spare plc that I can use for that part if necessary. But I would think there would be plenty since this thing contols 4 axes.

I am in the process of moving my shop - right in my busiest season - so I havent' got a whole lot of time, but I wanted to get started on this so I got something to look forward to while I'm moving. Got to have some kind of carrot, and doing this stuff is it.

Regards,
jimc