Thinking about a 5i25 board only

Hi everyone. I have a fairly simple (I hope) question. I have a 4 axis router that is working pretty well with a parallel port. I am using LinuxCNC V2.8 in MM mode on a HP RP5700 computer. My max jitter is about 32000. I have it set for 35000 and it's performing reliably. Only the stepper speeds are really slow, about 40 - 45 or so. I would like better performance, but I can live with what I have.

I am thinking about getting a 5i25 card to simply replace the parallel port. It looks like the hardware will do it. Has anyone tried this? I could not find out very much about it and Mesa has not returned my email. Are there subtle problems that I have not found in googling the heck out of it? I basically just want to know if I can get away with just the 5i25 card, or do I need a 7i76 with it.

I would greatly appreciate your input.
Thanks,
Chuck Tilbury
whistlemaker.com

unclechuck wrote: I basically just want to know if I can get away with just the 5i25 card, or do I need a 7i76 with it.

You can basically use a 5i25 alone as a souped-up parallel port.
It is simultaneously more and less flexible than a parport. Unlike the parport any pin can be input or output. But the function of each pin is determined by the firmware rather than LinixCNC HAL.

Are you sure that it is step-rate and not hardware that is limiting your speeds?

Yeah, we need more info about the setup, machine, config etc. Also 40 to 50 what???? In inches per minute that is ok, in mm per minute that is abysmal and unusable, except for engraving on granite and marble with a high speed diamond tip.
Attach your configuration files here so we can have a look.

andypugh wrote: Are you sure that it is step-rate and not hardware that is limiting your speeds?

No, I am not sure. I can set it up to step much faster, but it's not reliable at a higher speed. The stepper drivers are based on the TB6560 chip. It could very well be that the hardware is the limitation and increasing the step rate won't help. I don't know of a way to prove it one way or another. That's one of the reasons I am being a little cautious about just throwing money at it.

tommylight wrote: Also 40 to 50 what

That's MM per minute. You see why I want to increase the speed....

Should I post screen shots of stepconfig? Is that the info that will help?