General Help

Hi all,

I'm brand new to all this and am now pretty lost with where to start.

Here's what I've got so far...

Hurco 3 Axis KM3 cnc (old!)
Servo operated.
Mesa 5i25 + 7i77 cards

I've run the latency test and got an acceptable value for my Dell Optiplex 960
I've decided to go with AXIS for the user interface.
I've read the documentation about servos and mesa cards and even the HAL tutorial. - I can't say as I understand it all, but I've read it!

I've had a look through the PncConf utility but am now swamped as to where to begin.

Looking for a starting point here. I've got a machine with wires hanging out of it at one end and a computer with an interface board at the other. All help gratefully received. - Many thanks in advance.

Do you have a wiring schematic for the machine? You need to ID all those wires to know where to connect them.

Hi, thanks for such a prompt reply.

Right, well the CNC is using ServoMate AO-73187. I have some documentation for that (got it off this forum actually!) but it doesn't quite match my machine.
I've traced a lot of the cables and can identify points on the servomate that I will need to connect to.

Search for Hurco BMC20, i've done one already but had to change all the drives as they failed at random due to not being used for a long time.
If it is similar, i can help with it, i have some stuff written or drawn as i did not have all the documentation for it.

Thanks for the message, unfortunately the BMC20 doesn't seem to be very similar to my system.

I've managed to make a little headway with the configuration but have a general question that is throwing me off...

In the mesa config section of PNCconfig program I'm setting up my 7i77 card for PWM on each axis. The servo is controlled in the software by PID, details of which are in the documentation. However the ServoMate servo driver board that I will be connecting to on the Hurco is already controlling position with its own feedback closed-loop system.

Aren't these two control systems going to be at odds?

The other major problem I have is that the recognized outputs from the 7i77 don't seem to bare any relation to the inputs on the servomate, consequently I am still stuck as to 'what wire goes where'. For example - the servomate requires two speed control inputs (velocity controls) SIA and SIB, what might those equivalents be on the 7i77 config???

I've managed to get a couple of small motors spinning on the bench but as yet have not made any connections to the servomate. It seems a giant leap to go from these small 5v motors to the actual servos on the Hurco.
As always, all help gratefully received.

tjd wrote: In the mesa config section of PNCconfig program I'm setting up my 7i77 card for PWM on each axis. The servo is controlled in the software by PID, details of which are in the documentation. However the ServoMate servo driver board that I will be connecting to on the Hurco is already controlling position with its own feedback closed-loop system.

Aren't these two control systems going to be at odds?

Yes. If the ServoMate really does use position control.

But that seems unlikely if the input to to the driver is +/- 10V.

What position feedback does LinuxCNC get back from the machine?

Ah!
I might have gotten that a bit wrong then!
On the servomate I have the following inputs:

Velocity Command (SIA & SIB)
AUX Input
Tacho Feedback (From Encoders?)
Analogue Current
Current Limit
Left Drive Disable
Right Drive Disable

Do you have any idea as to how these might relate to connections to be made on the 7i77 card?

Servomate documentation can be found here:
www.skullworks.net/include/Servomate-AO-73187.pdf
This pdf doesn't quite fit my installation on the Hurco but its pretty close.

There are two feedback loops.

A velocity loop controlled by the servo drive, with feedback from the tachometer

A position loop controlled by LinuxCNC with feedback from scales / encoders / resolvers.

So you would leave the motor / drive / tachometer wiring exactly as it is and LinuxCNC will connect to the analogue command terminals and to the position feedback device.

First question: what is the position feedback device?

Feedback is from encoders. (Not resolvers). 5 wires coming out of encoders:
A out
B out
M out (not sure what that is so connected it to index on 7i77 ????)
GND
+5v

Since last post I’ve managed to get the X axis servo going via the speed control. Will be trying to get the encoders wired in and tested today.