I would go with analog. It is much easier to tune using Halscope than trying to tune the drives by ear or relying on auto tuning which in my experience doesn't work very well. Additionally if you get drive faults due to following errors it is much harder to figure out what is going on. With LinuxCNC handling the PID loop you can use Halscope to see exactly what is going on. Being able to actually see what is going on is so useful when trying to track down problems.

About a year ago I retrofitted a router with pulse controlled brushless servos, using Eding CNC instead of LinuxCNC. I spent ages on that machine tracking down intermittent following error trips. As it turned out the problem was actually a bug in Eding CNC but even then, if I had access to tools like Halscope I would have found the problem within hours rather than weeks. Unfortunately the customer did not want anything to do with Linux.

That is sad. Linux is not a dark art anymore. I looked at the data sheet carefully and I agree with you about using the analog system. The machine does not have a Z axis so I have to fit one. Getting servos over here is not that easy so I initially thought to go the pulse route. I suppose a small servo and drive would not be to hard to find on eBay.


Les

Hi

I have to upgrade and convert an old machine that was used to cut with
gas. It uses some Panasonic MCDHT3520 servo drives.
These drives has a pulsed input for position and an analog +- 10v input
for velocity mode.
The question is what mode is better to use with LCNC and Mesa cards,
velocity or position?

I will use one of the Ethernet solutions from Mesa with a panel PC.

-----------------------------
Regards / Groete

Marius D. Liebenberg
+27 82 698 3251
+27 12 743 6064




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