6 axis DMM servo setup

Ok, that makes a lot of sense now. Thank you for explaining it. Iv read about position mode being used for point to point applications like pick and place where its not as critical to control speed unlike machining. It sounds like velocity mode could still do everything position mode can.

Andy, you mentioned that it was possible to run 2 7i77 off of a single 5i25? I'm not sure how this would be done other than using a custom Y parallel port cable. I'm confused as to how it won't have conflict with the encoder feedback if two Motors are on the same axis? I'm still unsure of the size of Motors as I don't know the total weight of the machine I've been working on. I had initially planned to use two Motors on the Z lifting the XY gantry and two on the Y and one motor on x and two Motors on the rotational C axis along with one other motor which I met try to use some sort of spindle pwm output for. If I can use one motor on the z-axis that would definitely free up some pins. Although there's a lot more mechanics involved when lifting an entire gantry.

It might actually be an advantage to use stepper Motors on the z-axis since I could take advantage of dynamic braking. Is there any conflict between using 5i25&7i77 along with another 5i25&7i76? I wasn't sure if you can set specific axis to be analog or step/Dir in linuxcnc and haven't found any information on it.

The 5i25 can support 2 daughter boards, but you need to buy a cable to convert from the DIN connector to a parallel port connector for the second one.

So with one 5i25,you could have two 7i77s or one 7i77 and one 7i76 or all the other combinations.

And yes you can have two 5i25's if you wanted.

linuxcnc can have each axis use different interfaces (eg servo or step)

Chris M

Unless you need the extra io a 7i78 might be a better choice than a 7i76 for adding step/dir to a 7i77 5i25 combo.