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Author Topic: dspMC/IP control - General thoughts, compared to other options?  (Read 4527 times)

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dspMC/IP control - General thoughts, compared to other options?
« on: February 21, 2011, 04:40:08 PM »

So I'm wondering what other people's thoughts are on the dspMC/IP system. I currently have an Ajax / Centroid system in my CNC router, and I sort of regret putting it in there, mostly because it's badly supported, look-ahead and constant contouring don't seem to really work right, it's a horrible slow manual process to tune the PID loops, and forget using the auto-tune. In fact, I think I've been running my servos completely out of whack for 2 years now. You have to shut down mach AND the machine and restart the CNC and Mach just to TRY your PID settings. Totally convenient. Just like my Apple II/e. I know they're short handed there, but it's really just been a nightmare. They tell me to buy their Centroid software, but punching in all those unlock codes to even attempt to get autotune going in the Centroid software always ends in getting locked out .... Do I really want to give them another thousand bucks to have a system that still runs like crap? I'm  not really sure. The reason I sort of like the idea of the dspMC/IP is because it runs in MACH and in CNC Linux / EMC and probably some of DSps software too. Is it better supported? Can I do auto-tune ( I have 1KW AC servos with +/- 10V control) Is it stable? Does it have analog spindle control?  What about my MPG - Currently putting out differential quadrature, should work, right? My servos output differential quadrature too. Do I have to restart to try new PID settings? It homes to Index pulses, right? And the MPG connects to the unit directly, right?

What are people's thoughts? I currently have a machine that works and is making money, but isn't without it's fairly major problems, most of which I attribute to the Ajax/Centroid brain in the cabinet.
Re: dspMC/IP control - General thoughts, compared to other options?
« Reply #1 on: February 21, 2011, 07:13:53 PM »
Hello gumby:

That's quite a laundry list on Ajax. I was under the impression the Centroid/Ajax was pretty well debugged since they have been around quite a long time. However, they are a proprietary system, and the first order of business is keep their software locked up tight, and charge what the traffic will stand. That is pretty standard industry/corporate policy.
Regarding your questions about the Vital System, dspMC/IP controller, I have nothing but good things to say. The company is on top of any problems, and work with users to make things work. They are improving the software/firmware and make their updates available via the internet. There are no "special codes" to get things working.

There is no auto-tune, but the PID tuning is now done in a plug-in screen set with tabs for each axis, which is accessed from within the Mach3 program. No shut-down, restart. The tuning has a big graphic screen which shows visually the acceleration/decel curve vs time.  You can keep changing numbers, run an axis back and forth in real time, and play with settings until you get a best fit/feel/sound from the axis, then save your settings to the controller, and to the .XML file. There are more advanced settings on the tuning graphic that I have not used yet. My machine seems to really run fine and smooth with the basic settings that I found by experimentation, and the manual suggestions.

In my situation, the installation is a retrofit for an orphaned system that is now out of business. My motors are DC brushed, approx .7 KW, 100v Westamp amps, and the motors run smoother and faster now, than the original controller.

The controller has analog spindle control, and (3)MPG inputs directly to the I/O board. The higher end dspMC/IP controller has analog I/O, which is a nice option. I do not have that controller.

Quadrature encoder inputs, plus index via Z channel homing. All working a OK.   

There are two types of I/O boards. the 7535 is buffered and optoisolated, 12-30v dc I/O, and each board has 8 outputs, and 16 inputs. Using two boards in the J4,J5 position gives a total of 16 outputs, and 32 inputs. The corresponding Mach3 pin numbers are in a correspondence table, keeping everything pretty simple.

That pretty much sums up my experiences.

There are some very experienced, professional machine builders/users on this forum, who could give more detail regarding PID tuning.