Questions: Mesa 7I92 Leadshine MX4660 4-Axis Step

sakumar wrote: Looks like the MX3660 bitfile supports upto 3 steppers, but the MX4660 supports up to 4. So although the pins match for the first three steppers,
there is no support for the fourth.

I was confused for a while by the presence of a step pin for channel 3. But that is set up for a charge-pump.

Is this something I can fix via configuration or do I need to get a new bit file from Mesa?

If you are feeling adventurous it is possible to make your own bitfiles.
wiki.linuxcnc.org/cgi-bin/wiki.pl?Editing_MESA_Bitfiles

Here is a test bitfile for the MX4660 (and the changed source file)
freeby.mesanet.com/7i92_mx4660.zip

Update: The new bitfile for the Leadshine MX4660 (after download and reload), shows 4 steppers on P2. Also, I used the .ini and .hal files as-is (except for changing the IP address of the 7i92 back to 192.168.1.121) and linuxcnc basically comes up.

Thanks for all the help.

On to the next phase. Can I test the stepper outputs of the 7i92 (watching the step/dir pins on a logic analyser, for example) without actually connecting the MX4660? Say if I use the jog controls I should be able to see the corresponding activity on the 7i92's output parallel port, correct?

Sure, normal step/dir systems are open loop so step/dir signals can be watched on P2 pins
Also the sample config has no limit switch or or estop logic so does not depend
on any input states to run.

PCW wrote: freeby.mesanet.com/7i92step.zip
is a basic example hal/ini file set for the 7I92

You cal also run pncconf for a 5i25/probrfx2 setup and edit the resulting files
(changing the card name to 7i92 and the hostmot2 config line to include the 7I92s ip address)

I'm taking a stab at generating a .ini file because I want to add the 4th rotary axis to my configuration. Of course, I'll then edit it to use hm2_eth etc.

Here's what my latency histogram looks like. The numbers are a bit high but I'm assuming that's because linuxcnc is in user space. In any case, that's why I'm using the Mesa 7i92.

The Servo time stays at around 105 micro-seconds. So is it OK for me to set the SERVO_PERIOD to 120,000? Is there an advantage to doing this over leaving it at the default 1,000,000?

image missing http://i.imgur.com/8d6G1V6.jpg

sakumar wrote: The Servo time stays at around 105 micro-seconds. So is it OK for me to set the SERVO_PERIOD to 120,000? Is there an advantage to doing this over leaving it at the default 1,000,000?

1000 uS (the default) should be perfectly OK with a latency of 105uS.

You don't need a base thread, by the way.