Advice on what stepper + servo combo to use

Hi,

I have purchased two nema 23 servos with encoders to be used with pico AC servo amp. I want to use these for my Y axis gantry.
Along with that i have two steppers for my X and Z(These i will replace with servos, but probably dir/step drivers for them.)

I have mesa 5i25 and 7i78+7i48 now which I am happy with. What mesa board would I need to get to run my servos with?
I was looking at 7I85S, but the description at eusurplus confuses me a bit.

"A 7I85S version is available that replaces four of the serial interfaces with 8 differential ouputs that can be used as four differential step+ dir output pairs or PWM outputs or other output functions."

This seems like the one i would need, the way I see it it would be a straight replacement for my 7i78.

Is there a special 7I85S that I need to order to get the step/dir/PWM instead of serial interfaces?
If i were to get that board, would I still be able to connect to my 7i84 trough serial, like I have today with my 7i78?

Hope my question makes sense =)

/Peter

The 7I85S has 4 step/dir channels (or PWM/Dir etc) and 4 encoder channels and one serial expansion channel

The plain 7I85 has 4 encoder channels and 5 sserial channels

Thank you for the answer. That looks exactly like what I need.
I'll be sure to buy one of thoes.

/Peter

Hello again,

Is there any bit file firmware for 2 pwm gens and two stepgens for 7i85S out there? I believe that I saw a file with three pwm and one step.


Thanks

//Peter

HI, I don't mean to be naggy, but I'm really quite lost.
As far as I can gather, to run both step-gen and pwm-gen on one 7i85s I would need a .bit file that is build for this propous?

My goal is to be able to use the first port(7i85s) for motion/ and SSerial(7i84) board and the second port on a breakout board(7i75).

If there aren't a ready made, maybe there is a 7i85s+7i78 .bit file that someone has laying around? That would get me started.
Worst case: is there a tutorial that can get me started on building my own bitfile?

Thanks in advance
//Peter

Theres a 7I85S config with 3 stepgens, 1 pwmgen (with PWM and DIR brought out) and 1 sserial (a x2 config so the second port is also setup for a 7I85S with the same complement of encoders, stepgens, sserial, and PWM)

freeby.mesanet.com/5i25_7i85sspx2.bit

If you want something more custom you may have to make it yourself
there's a little info here:

wiki.linuxcnc.org/cgi-bin/wiki.pl?Editing_MESA_Bitfiles

I will give it a shot making a custom one. Thanks!

//Peter

a quick question about pin files..
stegens have 2 pins step & dir why the code isand not?
The code with only x"81" x"82" will work ?

Sure , even code with only x"81"s will work, you just wont have any direction pins

The stepgen supports a table driven mode with up to 6 outputs, and many of the 24 pin FPGA example bitfiles
support all the table pins

Hello again,
Please forgive my ignorance, totally new at this.
I cant seem to find the .vhd file for 5i25_7i85sspx2.bit. Is it included in the hm2epp under and diffrent name?

/Peter

EDIT: Never mind, I want looking good enough =)

EDIIT #2 Thought I found it, scratched my head for a long while.realised that I has found PIN_7I85SPx2_34.vhd not PIN_7I85SSPx2_34.vhd.
Im getting to tiered to read properly, new try tomorrow. =)