Choice of Mesa cards for servo or stepper machine

I've spent some time getting familier with Linuxcnc using parallel port, BOB, cheap driver/stepper set up. I've also used a small dc motor with a 60 slot disc attached, to simulate a lathe spindle. Three slotted optical switches are used to give quadrature encoding for threading.
I've also used classic ladder to create a tool change program for a lathe. Thanks to the members of this forum for the help I've received with this learning process so far.
I would like to move on to a Mesa card set up. Intially to use for step/direction control, but with the ability to swap to servo control (closed loop, up to three axis) at a later date ( I have a second parallel port in a PCI slot so have plenty of I/O).
I guess I would need one of the plug and go kits, is there one that can do step/dir or servo control?. Sorry to ask such a general question, but my experience so far is that you have to set up and run some hardware with Linuxcnc to get some idea how it works.

Thanks, John.

It really depends on the servo drives
You can use step/dir controlled servos with the same controller hardware as step drives
If you wish to have the control loop closed by LinuxCNC you need enough encoder inputs
for all axis + spindle plus servo drives that output encoder position for LinuxCNC .

So for example a 5I25/6i25/7I92 (PCI/PCIE/Ethernet) + a 7I85S will give you 4 axis of step/dir outputs + 4 axis of encoder inputs
+ a serial expansion channel for more digital I/O so both open and close loop step/dir systems can be supported

If you later changed from step/dir to analog +-10V servo drives its more awkward to upgrade
since the step/dir card is not of much use (but the FPGA card = 5I25/6I25/7I92 will work with any system)

Thanks for the explanation. I have a lot to learn about this!. It appears, using Mesa boards, I could have an open loop step/dir system, a closed loop step/dir system (depending on servos), and a closed loop analog servo system. I'e been offered a 5i25/7i76 new and unused, so I'll buy these and start with an open loop step/dir confg. It appears I could buy a 7i77 and use with the 5i25 for a servo config at a later date.

raglanlittlejohn wrote: I'e been offered a 5i25/7i76 new and unused, so I'll buy these and start with an open loop step/dir confg. It appears I could buy a 7i77 and use with the 5i25 for a servo config at a later date.

If it matters, you can use a single 5i25 with a 7i76 _and_ a 7i77 at the same time. The 5i25 has two 25-pin ports

Thanks for the confirming the 5i25 will run the 7i76 and 7i77 at the same time. On a related topic, would the 5i25/7i76 combination be suitable for your hobbing set up. Is that set up open loop please.

raglanlittlejohn wrote: On a related topic, would the 5i25/7i76 combination be suitable for your hobbing set up. Is that set up open loop please.

Yes, that should be possible. The 7i76 has provision for a spindle encoder, which is really all you need.

I hope is OK to ask here similar question?

Does 5i25/7i92 + 7i85s is OK combination for 4 axis with encoders?

I bought 4 CL57T closed loop stepper drives from here and 4 closed loop stepper motors (2 for Y, 1 for X, 1 for Z axis).

I want in the future add one more axis.

Which is better or easier for setup PCI (5i25) or ETH (7i92)?

Sorry for my English and THANKS IN ADVANCE!

Yes those would be appropriate for step/dir control + encoder feedback for a 4 axis system. You may also want to consider adding a smart serial card for digital I/O (limit switches...) such as a 7i84.

Adding a 5th axis to that combination may be a problem. Because the 5i85s only supports 4 axis. If you want to go Ethernet connected and eventually have 5 axis, a 7i76e+5i85s might be a better option.

As to whether or not to choose a 5i25 (or 6i25 PCIe version) over a 7i92, they are more or less functionally equivalent. Unless you need to run a super fast low latency servo-thread, then maybe stay away from the Ethernet card, but that is a rather unusual case.

As to ease to configure, an Ethernet card has a slight disadvantage, in that you must first configure it's Ethernet connection. After that I don't think they are much different from the ordinary PCI bus cards.

Typically with that type of drive you would just use step/dir and the encoder feedback is local (to the drive) only
so a 5I25/7I76 or 7I76E would work

Thank you very much for fast replays!

If I understand, 5i25 + 7i76 is better combination then 5i25 + 7i85s for me, because in the future I can add one more axis and will have more inputs for limit switches, pendant?