7i80 and 7i77

Even then it is approximately the same price. 7i80 for example:

duzi.cz: EUR 165.45 plus EUR 23,05 shipping with Czech mail = EUR 188,50.
mesanet webshop: USD 149.00 plus USD 43.75 shipping = USD 192,75 = ~EUR 145. But customs might catch the package and add VAT, import duty, etc., And then total price goes up towards the duzi.cz price.

Cannot compare the 6i25 since duzi.cz does not stock it and the other European distributor's website is offline.
But since duzi.cz is not a serious distributor in my opinion (most cards are 'sold out' for months already) the choice is not that difficult.

Can one use multiple 6i25's in one system if it turns out that i need 8 encoders and 5 step drivers?

DaBit wrote: Can one use multiple 6i25's in one system if it turns out that i need 8 encoders and 5 step drivers?

Yes. In fact you could have as many 6i25s as there are PCIe ports, as many 7i43s as there are parallel ports, as many 7i80s as you can afford routers for. At some point it would all run out of CPU at the PC end.

it might be possible to have 8 encoders and 5 step drivers all on one 6i25 though. A 7i76 + 7i77 config (the 6i25 and 5i25 have two ports, one on a header) has 5 step drivers + a spindle encoder on the 7i76 and then
The 7i77 has several real encoders and also some (onboard) MPG encoders.
I think there are 3 encoders on the (small, cheap) 7i73 board, and you can hang one of those off of the 7i76 (and most of the other DB25 cards) and 8 of them off of the 7i74 board.

Ordering 7i76/7i77/whatever breakout board might be useful, but I do have working electronics on a (home brew) PCB that accepts a DB25. I might want to continue that route since I already use home-brew stepper drives around dsPIC33F DSP's and I do want to continue on the stepper-with-linear-scale-feedback path. My earlier experiments on the BF20 were quite promising, but that machine has too much mechanical backlash. The sound of a hunting 'servo' certainly makes you feel nervous.

I have this idea to run the steppers in velocity mode using FOC / vector drive as 'regular' high torque/low RPM motors. Voltage mode drive would make it easy to detect (and act upon) stall, would not suffer from the 90-degree phase shift a current-mode drive encounters when it runs out of bus voltage, and it doesn't produce the typical 'stepper noise'. And because a stepper with stall detect is fully synchronous I do not need a rotary encoder on the shaft and it makes life for the servo loop very easy since actual RPM is extremely close to commanded RPM. Final position feedback through 1 micron linear glass scales. Sounds like a great setup for machines that do not need more than ~200W of mechanical power to drive the screws. Stepper motor+drive+scale costs less than a single servo motor+drive.

a gantry style machine needs at least 4 axes worth of linear encoders, and possibly shaft encoders which totals to 8. Initially 4 step/dir interfaces are needed; and later on PDM (or a SPI protocol) to the drives to command velocity might be more suitable.

Whether a card supports the amount of encoderrs/stepgens or not depends on the firmware. In this[.url] document there is not much information about the 5i25/6i25.

DaBit wrote: In this[.url] document there is not much information about the 5i25/6i25.

Almost no information, in fact.

The DB25 boards actually only use 17 pins, just like a parport. These pins tend to be either stepgens or encoder counters (the encoder counters may be muxed to double them up). The GPIO and analogue outputs are serially-interfaced using the mesa "Smart Serial" protocol, which is proprietary but fairly open. At least one business is making clone cards that run Mesa hostmot2 configs, but I think that is only for their own products, rather than being in direct competition.

So, you can probably do what you want with a 6i25 which has the 7i76 + 7i77 firmware, but without using those actual daughter cards.

retrofit-plus.at in Austria sells the 7i80 card. But I asked him and he says, the card don't works correctly. Maybe he only have'nt the newest Software and drivers.

uli12us wrote: retrofit-plus.at in Austria sells the 7i80 card. But I asked him and he says, the card don't works correctly. Maybe he only have'nt the newest Software and drivers.

If I was selling them I wouldn't sell the 7i80 to anyone at the moment unless they insisted. As a vendor it would be asking for support troubles.

Having said that, if you do not expect plug-and-play it does work.