New 7i95t Open Loop Stepper Driver Issues

I’m trying to test run my new Mesa 7i95t. I am completely new to LinuxCNC but have lots of CNC (and programming/linux experience FWIW). Before I start touching anything in my DIY machine (currently running on FluidNC) I just want to get a single stepper driver to run a single stepper motor so that I can complete the flow end to end. As a sanity check I’ve hooked up a DM556 stepper driver to the card’s stepgen 03 connector (tried both a differential connection and also just connecting PUL- and DIR- on the driver to stepgen’s ground). The stepper driver is powered by a 24v PSU and works perfectly if I just connect its PUL to a pulse generator. The ENA is left unconnected, enabling the driver. I’ve setup the Mesa config with pncconf using 7i76 as the card and then later switched to hm2_7i95.0 in the INI as per the instructions. Assigned stepgen 03 to the X axis. LinuxCNC starts fine, I can unlock the machine and jog, and see the DRO changes values - but the stepper doesn’t move. Looking into the generated HAL file, I see control type set to 1 (velocity and not position? does this make sense for a stepper driver like this)? Also, I see a bunch of pid initialization, and again it’s confusing to me why PID is needed for an open loop stepper driver that provides no encoder feedback to LinuxCNC. What am I missing here? Is there a sample HAL file that works with the 7i95t and a simple open loop stepper driver that I can test? Thanks!

forum.linuxcnc.org/show-your-stuff/47357...hines?start=0#256463
Attached Messer_big is for 7i95 (not T) and uses encoder feedback and is for plasma, so just take it as a reference to compare to.

The most common issue with lack of motion ins step/dir systems is too short
pulse width settings. I would always start with at least 5 usec (5000 ns)
for the step pulse length.

Another common issue is insufficient drive, which is why its suggested to wire 
opto-isolated step/dir drives in single ended format as this reduces the drivers
source resistance by 1/2.

Single ended:

7I95        DRIVE

STEP+    PUL+
DIR+       DIR+
GND       PUL-,DIR-

The PID setup is intentional.

Note that the latest pncconf ( in LinuxCNC master ) has direct 7I95/7I95T support

 

thanks, will test that.

btw - I have installed the latest release of the linuxcnc debian - 2.9.4 - and there is no 7i95 option, is the version on master newer but not released?

Master is 2.10

So you would need to build from source or get a snapshot from the buildbot
to update to master.

BUT... you should be able to just replace the current pncconf pieces with these:

forum.linuxcnc.org/39-pncconf/56464-mesa...thcad-pncconf-screen

( Thanks kworm )


Another option is MesaCT which has had 7I95/7I95T support for a long time.

 

pulse width was already 100,000 ns so that wasn’t the issue.

i downloaded mesact, chose 7i95t and when i switched to the firmware tab got a message that no firmware was found, prompting me to download it which i did.

then built the config, and it worked perfectly right off the bat so firstly thanks so much for the help here!

i’m curious what this missing firmware was - since no flashing happened im to understand this isn’t the board’s firmware, so i’m assuming then its firmware on my desktop for communication with the 7i95t?

before, i was using hm2_7i95 which was available to the HAL (not 7i95t which the HAL complained about being missing once I ran LinuxCNC with it initially). so this is just hm2 “driver” firmware for 7i95t which was missing on my debian?