USB/Ethernet controller for Mach3/4 advice

[JAZZCNC]

Thanks Gerry, I've never heard of CS Labs before. Their products look fine and have good prices. What about the analog axis control mode? Does it have any benefits over the step/dir? Smoother operation or it is only for use with older drives?

Cslabs controllers are best I've used and nothing but Galil comes close and they cost much more money.

The only advantage the IP-A gives over the IP-S is encoder feedback to the controller so you know what the DRO display is the actual position of the motor.
With the IP-s you take it on faith the drive arrived at the location it was commanded to go, there is no feedback to say it arrived there.

[paulus.v]

Thanks Jazz, now I'm a bit confused, not sure which one is better to use, the analog or digital...

[JAZZCNC]

Thanks Jazz, now I'm a bit confused, not sure which one is better to use, the analog or digital...

There is no best really both will work and perform just the same. Only difference (other than no Step/dir) is with the IP-A version you'll get encoder feedback to the controller so will know the exact positon of the motors. It won't make it any more accurate than IP-S.

If you plan to ever use Steppers or drives with Step/Dir then go with IP-S.

Me persoanlly if using servo's with -10/+10v I'd be using IP-A for the Encoder feedback but I'd happily run the IP-S which I do on my own machine.

Edit: Where the IP-A does win over the IP-S is if your using Spindle with encoder as it can control the spindle rotation/position for things like ridged tapping. This is why they are often used on lathe retro fits or industrial Mills with ATC/Ridged tapping.

[paulus.v]

I'm helping a friend converting a mill and all this servo stuff is new to me, so I still have a lot of questions I cannot find the answer here..

What is the best approach for homing? Using micro-switches and the encoder z output? Or there is no need for accurate homing.

How to wire the e-stop? For steppers I cut the power to the motor but here I have e-stop input at drives as well as controller. If I use the e-stop this way, the machine will not lose its position, and I can continue the work without homing the machine. Am I right?

[EddyCurrent]

I'm helping a friend converting a mill and all this servo stuff is new to me, so I still have a lot of questions I cannot find the answer here..

What is the best approach for homing? Using micro-switches and the encoder z output? Or there is no need for accurate homing.

How to wire the e-stop? For steppers I cut the power to the motor but here I have e-stop input at drives as well as controller. If I use the e-stop this way, the machine will not lose its position, and I can continue the work without homing the machine. Am I right?

I've used encoders many times but not in the context of cnc machines. As I understand it, homing works as you suggest, the switch detects the gantry approaching home and tells the system to start counting the encoder pulses to actual home position.

Regarding e-stops, most people would kill the power if an e-stop was activated because it's an emergency situation. If you want the machine to stop you should use a 'Stop' button instead.
Either way if power is left on to the encoder and Mach3 for example then the position should not be lost. If the encoders are absolute as opposed to incremental then they will always know their position even if the power has been off. As I mentioned this is how they work on equipment I've used in the past, maybe wait until a cnc user replies for more appropriate info.

[paulus.v]

Thanks Eddy, I think most of the encoders are incremental and some sort of homing is needed. As I understand, in the switch based homing, when the switch is triggered the encoder goes to Z which is one pulse per revolution. If one rev. =1.5mm movement, I assume that a switch repeatability of less than 0.75mm will do the job.

On my stepper based CNC the limit switches are wired in series with the e-stop and cuts the power to both spindle and steppers, not the electronics and triggers in mach3 an e-stop to pause the g-code. But with servos if both the drives and the controller have an e-stop input, which means double protection, is there any need to cut the power?

[JAZZCNC]

Do the drives have a Home and Index sync option.? Some drives will let you connect a switch to Home input on the drive and then they will sync the index pulse(z) of the encoder to position the motor.

What controller are you using.? Some controllers like the Cslabs will Home to index pulse or a set number of pulses after home switch detection.

Regards E-stop then you should always assume position is lost after hitting so therefore need to re-home to ensure accurecy. Like Eddy says E-Stop is emergency so should Kill power. Feed hold or pause or general stop is a controlled halt and doesn't lose or require homing.
Like wise a Limit trip isn't really an emergency situation it's a positional error so I wouldn't kill power to this action just halt drive outputs and inform controller it's happened. This will keep the drives powered and holding torque but really you will still have lost position thru inertia etc so homing will be needed.

[paulus.v]

I will most probably go with the CSMIO/IP-A.

The encoder has the index pulse. I don't think the drives have home inputs. There are CW Limit, CCW Limit and E-stop inputs. And an input called 'Zero clamp' I have no idea what it is for.

Is it safe to use only one switch on each axis side for both soft limit and home?

EDIT: where is the best place to put the home switches? For the X is it better in the middle? and for the Z?

[JAZZCNC]

I will most probably go with the CSMIO/IP-A.

IP-A is perfect control and very easy to do this using the encoder index pulse. See manual how to do it.

And an input called 'Zero clamp' I have no idea what it is for.

Are these brushed DC servo's.? if so then be careful as the encoders are probably single ended and not differential which the IP-A requires.

Is it safe to use only one switch on each axis side for both soft limit and home?

Soft limits doesn't use switches it's exactly that limits set in software so no switches involved. It's safe to use shared limit and home switches if your stuck for room or inputs but with so many i/o why.?