transitioning from smoothstepper to mesa?

Hi guys, I've searched but couldn't find a situation quite like mine. Hope I'm not asking a redundant question. here goes...

I've got a miling machine whose electrical cabinet was done by MachMotion. They make their own breakout board called the Apollo I and it mates with an Ethernet Smoothstepper. I've found the smoothstepper troublesome for long jobs as it sometimes loses communication with the PC resulting in a trashed work piece. This has happened a few times and has me contemplating a move to something more robust.

The Apollo I connects to the Smoothstepper via two parallel ports. It outputs to the rest of the electrical cabinet via RJ45 connectors (X,Y,Z,A, and spindle control). I've attached homing switches to the inputs on the break-out board but made no other changes. (just checked the board's pictures and it appears to have a third port labeled SS-port which is not mentioned in the Apollo-I documentation, going to call the OEM and ask what that does tomorrow).
Since the rest of the cabinet seems to be working fine and I don't want to redo any of the OEM's wiring so I'd like to stick with the Apollo I breakout board if at all possible. I'd also like to continue using an ethernet based connector as this would allow me to move to a small sealed PC such as an intel NUC with fanless case. I've had problems with wood dust getting into the current non-sealed Mach3 machine.

Before I begin ordering parts, I figured I should ask a few noob questions:
1. Would an ethernet based mesa card allow me to use a computer which has moderate latency? (the intel NUC I have earmarked for this project has latency of 50k under heavy use)
2. which Mesa card work work best for my break out board? Is the 7i80DB the one I need?
3. In the future if I were to add linear encoders for my X,Y,Z axes could the 7i80 handle that? Would I need another break-out board?

thanks in advance for any advice

I think that would work and I doubt you would need another board. I also think a 5i25 or 6i25 would also work.

If you also want to add the encoder feed back, you will probably need to add another board.

Thanks for the reply.
I've spent the past few evenings reading the users manuals for my current components.
My XYZ motors are Teco 750W servos, controlled by Teco drives. Apparently they're running in step-direction mode with Mach3 right now.

They have three connections, one for motor control output, one for encoder input, and a rs-232 com port. The rs232 is unconnected, and runs at 9600 bps. I presume this is far too slow to be useful to carry any encoder output to a control PC.

The encoder port gets the value from the servo's encoder. It connects to the drive via a 20 pin connector.

I'm still filling in gaps in my understanding here, so please forgive my naive questions, but here goes:
Assuming I wanted to go closed loop back to LinuxCNC...
1. Do I need to fork the connector; meaning both drive electronics and linux cnc get the encoder signal, or only send the encoder output to linuxcnc ?
2. What kind of daughter board would be needed connect between the three 20 pin connectors and a Mesa 7i80db ?

Is there a primer or wiki entry some place that shows a practical step by step for a similar servro configuration?

thanks in advance

this is a servo system , so take a look at using a mesa 5i25 & 7i77 interface , this gives you pwm outputs for the servo's , encoders , an analog 0 - 10v , should be all you need .
if you want to use step direction then you can use a 7i76 interface . although if the servo drives can be input by pwm that would be far better than step direction in my opinion, but perfectly adequate .

9600 rs232 is woefully slow , that's probably only a setup input from a windows configuration program purely for the amps

their should be an output from the servo amp for the encoder , so that would go to linuxcnc .

you wont find a pin for pin adapter , you are going to have to manufacture the wires between the connector of the drives and to the 7i77 , a simple operation .
noting in this life is plug and play

is their a reason you wish to use the 7i80 ?

It looks like the Apollo1 breakout should work with either the 7I92(H) or the 7I80DB
Though at first glance their manual does not document the parallel interface pinouts very well.

The advantage of the 7I80DB is that you could add encoder inputs later if desired
(The 7I92 would use all of its I/O to drive the apollo1)

50 uSec latency is fine, though latency must be tested with a Preempt-RT kernel
which is what the mesa Ethernet card use

Hi Andy, sorry for being unclear. A top down description of my mill would look similar to what you've described:

Mach3 -> (via ethernet) -> SmoothStepper -> (direct plugin) -> Apollo I -> (via RJ45) -> Tech drives -> Tech servo motors

That is how the system was configured by MachMotion and the OEM. I have no quarrel with the Apollo I and no particular desire to re-wire the electrical cabinet as it works quite well driven via RJ-45. I am fully open to replacing the SmoothStepper and Mach3. I'm OK with adding additional daughter boards as necessary, but I'd like to keep the Apollo I as it is already in place and seems to work without issue. Admittedly, yes, it is an expensive breakout board and I would not go that way if I were spec'ing the system from scratch.

Regarding the two ports, yes both appear to be in use by Mach3. I have spindle, X,Y,Z and A axis (rotary table connected to a stepper motor), e-stop, and three limit switches. Near as I can tell, mach3 is treating this as an openloop system and has no knowledge of the actual positioning of the encoder.

The following is a pic I sent MachMotion asking for clarification about the ESS.
Turns out it is a little different than a stock ESS as they've inverted pins on the circled ports. This lets them connect the ESS directly to the Apollo-1 without any additional cables.
They did not have record of it and said it was likely a custom job for my mill's OEM. I don't see it offered on their website. The OEM claimed that the ESS was provided that way by MachMotion.



What kind of daughter board would I need to go along with a 7i80db to capture three encoders worth of feedback?
Also, would I be sending the encoder values to BOTH my Tech drive and LinuxCNC, or just linuxcnc?

thanks in advance

Typically modern servo drives have local encoder feedback _and_ a simulated encoder output.

This simulated encoder output is what would be feed back to linuxcnc for position feedback control,
not the motors encoder signals.

PCW wrote:

It looks like the Apollo1 breakout should work with either the 7I92(H) or the 7I80DB
Though at first glance their manual does not document the parallel interface pinouts very well.

The advantage of the 7I80DB is that you could add encoder inputs later if desired
(The 7I92 would use all of its I/O to drive the apollo1)

50 uSec latency is fine, though latency must be tested with a Preempt-RT kernel
which is what the mesa Ethernet card use

I had a similar complaint about the actual pin connections in the manual, but I suspect I could note down the configuration from Mach3 and try to duplicate it for linuxcnc/7i80db.

From what I can tell the encoder input to my Teco drive is done via 20 pin centronics connector.
I suspect I'll need to find a way to go :
20-pin centronics -> header / breakout -> daughter board -> 7i80

Sound about right?