[HighSideNZ]

Hi again
I've run out of ideas trying to get the servo motor running as a spindle.
The servo driver is set up to work in Speed mode using the 0-10v analog output from the MB3
The servo motor runs as expected when using Jog mode etc. directly from the servo driver but I cannot get any output when trying to control it via Mach4 etc.

I have 3 relays being controlled from the MB3 for, spindle enable, CW and CCW rotation.

Checking my wiring, I'm getting a 0 to 10V signal at the driver and well as the spindle enable etc. outputs.

I think I've followed the details in the driver manual but as this is the first servo I've worked with I may be completely off the mark.

I've attached the manual for the servo driver.

I'd appreciate any assistance.

Cheers
Phil

[joeavaerage]

Hi,
I have a 1.8kW Allen Bradley servo as a spindle motor. 99% of the time when I use it I too use it in Velocity mode, that is to say the spindle rotates with a 0-10V analogue voltage.
There are a few options, including a -10V-0V-+10V analogue voltage which would cause the spindle to rotate in both directions. This is not necessary for me so I don't bother with it, but is
essential if you were using this servo as an analogue servo, maybe as a replacement for an older servo.

To control my servo spindle I have just one relay, an On/Off and an analogue voltage. It works fine, and is very similar to a VFD controlled asynchronous spindle.

The Allen Bradley drive, and I imagine your drive would be similar has a 'dual mode' operation. This is what I have selected. Its primary mode is Position, and its secondary mode
is Velocity. Which mode the drive operates in is determined by one digital input. If it is asserted then the servo operates in Step/Direction mode like a regular servo, and if the input
is de-asserted then it operates in Velocity mode. This later mode sees by far and away the most use. Pretty easy really.

You say you are getting a 0-10V signal at the drive. That suggests a few possibilities:
1) That you have not programmed the drive to be in Velocity mode, OR you have programmed it to be in dual mode as I described above, but is still in Position mode despite your best efforts.
2) That you have not programmed the Enable correctly. Remember when you jog from the drive you are in effect asserting the Enable, but in absence of a Jog signal the drive might revert to its
Un-Enabled state.
3) The drive is faulty, unlikely but not impossible.

May I suggest that you get a small 9V battery and use that to supply the analogue voltage....that eliminates any potential fault propagating from the MB3.
You may find that you need to reverse the polarity of the signal for instance.

Is there any need to have CCW rotation? I know I spent a lot of time and energy on my first mini-mill to get both directions and then hardly ever used it. I came to the conclusion it was a waste of time.
The only time I need the spindle to reverse is when I'm rigid tapping and for that I use Position mode anyway, I don't need it in Velocity mode.

Craig.

[HighSideNZ]

Thanks Craig
I'd not thought of using the 9V battery as a test. I'll give it a try.
My drive has 3 modes by the look of it. Position, Velocity and Torque.
I'm pretty sure I've configured it correctly for Velocity but I'll go thru the process once more to be sure.
I was thinking of using a toggle switch on the Servo Ready input as a test to make sure I'm getting that turned on.
In saying that, If I have Mach4 Enabled, the servo is energised and holding as I cannot manually turn the motor shaft so that would indicate that Servo Ready is on.
Thanks for your input once again.
Cheers
Phil

[joeavaerage]

Hi,

I'd not thought of using the 9V battery as a test. I'll give it a try.

Yeah, its convenient. Totally isolated and I always have a 1kOhm resistor in the circuit so its current limited, just while you're messing around.

Just as a matter of interest I believe the MB3 has an isolated 10V DC supply with which it produces the analogue voltage. It uses an isolated internal DC-DC converter.
That does mean that its totally isolated, and if you wish to use it to drive your servo then the 0V of that supply MUST be refenced to the 0V COM of the servo drive.
Have you done so?

Craig

[HighSideNZ]

When you say "referenced" to the 0V COM of the drive, exactly what do you mean?
When I run the drive analog display option, a built in option to display the incoming analog voltage it is receiving, I get what I would expect to see and tallies with what my multimeter displays.
Does that not mean that the drive is receiving the correct analog voltage?

Phil

[joeavaerage]

Hi,

When you say "referenced" to the 0V COM of the drive, exactly what do you mean?

I mean connected. The 0V Com of the servo must be connected to the 0V of the floating supply. Although it would appear that if the drive display is registering the voltage then
surely you already have a reference.

Does that not mean that the drive is receiving the correct analog voltage?

That's where the 9V battery test comes in....how or why do you think I came up with that idea? With the battery I was able to prove that the VFD (on which I was working at the time) was working
and therefore I must be interfacing the analogue voltage to the VFD.

Craig

[HighSideNZ]

OK, thanks
I'll keep on digging

Phil

[joeavaerage]

Hi,
most servos have a number of parameters governing how the analogue voltage is treated/used. Things like Offsets, Linearity, gain and so on. I imagine your servo has them. Does it have setup software?

Craig

[HighSideNZ]

Hi

No there is no software for setup.
I've got to do the config directly on the drive via the built in push buttons.
Yes there and a number of parameters directly associated with the analog signal.
I'll work thru them.

Phil

[joeavaerage]

Hi,

No there is no software for setup.

That was a mistake. Cheap Chinese stuff seems to work OK, but unless you've set up and tuned servos before you will struggle with these servos. Poor to atrocious documentation and no set up software.
Cheap is about the only advantage you got.

Craig

[HighSideNZ]

Hi
I was hoping you weren't going to say that!
I assumed it would be similar to setting up a stepper.
Oh, how wrong was I
Phil

[joeavaerage]

Hi,

I assumed it would be similar to setting up a stepper.

Perhaps that is true of the few essentials....but a servo has way WAY WAY more going on than that. My Delta servos have 270 parameters split over four pages. Most of which you'll never
touch, but there are many that you will need to use sensibly.

The screen shot is from Ultraware, the software from Allen Bradley. Note with my Allen Bradley you MUST have the software, you cannot program the drive by pushing buttons, there aren't any!

Craig

[HighSideNZ]

OK
Gave up on the Velocity control scenario and have gone with Step/Dir.
Got it working a treat.
So I'm going to call that a win.
Thanks for everyone's input.
Cheers
Phil