Note: I previously sent this message to the emc-users list but was told this one was for BDI4 specific questions. The other list was for EMC2 issues. I'm currently running BDI 4.38 on a Pentium2-400Mhz PC. I recently installed a new 276oz-in stepper motor on my X-axis and trying to tune EMC for higher rapid speed. The fastest reliable speed I can get is 25IPM (500RPM, 20TPI leadscrew, 13333 pulse/second) with my 8microstep driver. Anymore than 30IPM, you can hear the stepper motor getting rough sounding (jitter??) and motor stops spinning. The period is set at 0.000007. I have tested it set at 0.000005 (any lower PC locks up and resets) but I still can't get any faster or more reliable pulse out of the parallel port. I played around with the P setting but just makes it worse if set over 1000. I currently set the MAX_VELOCITY = .41 (25IPM) since that seems to be the most reliable speed I can get for now. Anyone out there running a similiar speed PC and what is your fastest pulse output? 13,000 steps/sec seems rather slow to me. For comparison, I unplugged the parallel cable and hooked it up to my lowly pentium233 laptop running Turbocnc. I was able to get the same motor/driver to spin at 1200RPM with no problems. At 25IPM (500rpm) the motor sound so much smoother then EMC. Actually a little bit scary watching the table move back and forth at 60IPM since I only have 12" of X travel. I've been running bdi-2xx for the last 3 years or so and have just recently upgraded to 4.38 due to hard drive update. I also went through the archives and saw the reference to Quickstep. I'll do a apt-get and test it out however I do use backlash compensation on my mill. Regards, Jim # Task controller section ----------------------------------------------------- [TASK] # Name of task controller program, e.g., bridgeporttask TASK = bridgeporttask #TASK = minimilltask # Cycle time, in seconds, that task controller will sleep between polls CYCLE_TIME = 0.010 # Part program interpreter section -------------------------------------------- [RS274NGC] # File containing interpreter variables PARAMETER_FILE = emc.var # Motion control section ------------------------------------------------------ [EMCMOT] # Name of motion control program # Don't use an extension with the module name - The script works it out. EMCMOT = freqmod # EMCMOT = smdromod # EMCMOT = vitalmod # Key for real OS shared memory, e.g., for simulated motion SHMEM_KEY = 100 # Base address the DRO card when using smdromod.o # DRO_BASE_ADDRESS = 0x200 # Address for parallel port used for steppers IO_BASE_ADDRESS = 0x278 # Timeout for comm to emcmot, in seconds COMM_TIMEOUT = 1.0 # Interval between tries to emcmot, in seconds COMM_WAIT = 0.010 # Base task period, in seconds PERIOD = 0.000007 # Trajectory planner section -------------------------------------------------- [TRAJ] AXES = 3 # COORDINATES = X Y Z R P W COORDINATES = X Y Z HOME = 0 0 0 LINEAR_UNITS = 0.03937007874016 ANGULAR_UNITS = 1.0 CYCLE_TIME = 0.010 DEFAULT_VELOCITY = 0.02 MAX_VELOCITY = .6 DEFAULT_ACCELERATION = .7 MAX_ACCELERATION = 2 PROBE_INDEX = 0 PROBE_POLARITY = 1 # Axes sections --------------------------------------------------------------- # First axis [AXIS_0] TYPE = LINEAR UNITS = 0.03937007874016 HOME = 0.000 MAX_VELOCITY = .41 MAX_ACCELERATION = 2 P = 100.000 I = 0.000 D = 0.000 FF0 = 0.000 FF1 = 0.000 FF2 = 0.000 BACKLASH = 0.0015 BIAS = 0.000 MAX_ERROR = 0.000 DEADBAND = 0.00025 CYCLE_TIME = 0.001000 INPUT_SCALE = -32000 0 OUTPUT_SCALE = -32000.000 0.000 MIN_LIMIT = -20.0 MAX_LIMIT = 20.0 MIN_OUTPUT = -20 MAX_OUTPUT = 20 FERROR = 1.000 MIN_FERROR = 0.100 HOMING_VEL = 0.1 SETUP_TIME = 1 HOLD_TIME = 2 HOME_OFFSET = 0.0 ENABLE_INDEX = x ENABLE_POLARITY = 0 MIN_LIMIT_SWITCH_INDEX = 1 MIN_LIMIT_SWITCH_POLARITY = 0 MAX_LIMIT_SWITCH_INDEX = 0 MAX_LIMIT_SWITCH_POLARITY = 0 HOME_SWITCH_INDEX = 2 HOME_SWITCH_POLARITY = 1 HOMING_POLARITY = 1 JOGGING_POLARITY = 1 FAULT_INDEX = x FAULT_POLARITY = 1 DIR_INDEX = 0 STEP_INDEX = 1
Hi Jim On Friday 03 March 2006 15:50, Jim Fong wrote:
I'm currently running BDI 4.38 on a Pentium2-400Mhz PC. I recently installed a new 276oz-in stepper motor on my X-axis and trying to tune EMC for higher rapid speed. The fastest reliable speed I can get is 25IPM (500RPM, 20TPI leadscrew, 13333 pulse/second) with my 8microstep driver. Anymore than 30IPM, you can hear the stepper motor getting rough sounding (jitter??) and motor stops spinning. The period is set at 0.000007. I have tested it set at 0.000005 (any lower PC locks up and resets) but I still can't get any faster or more reliable pulse out of the parallel port. I played around with the P setting but just makes it worse if set over 1000.
I currently set the MAX_VELOCITY = .41 (25IPM) since that seems to be the most reliable speed I can get for now.
Anyone out there running a similiar speed PC and what is your fastest pulse output? 13,000 steps/sec seems rather slow to me.
Dug out my little Sherline and ran a few tests this morning. The computer is a Celeron 433 with a 440BX chipset, and a C&T 69000 graphics controller (2MB memory running at 800x600), currently with 256M of memory installed. Probably close enough in specifications to do a reasonable comparison of EMC's performance.. The stepper motors on the Sherline are fairly wimpy little NEMA23 rated at 134oz-in running from a unipolar driver - Not the best combination for maximum performance.. About the best I can achieve is 25ipm with a 7.5uSec base period before the motors start squawking and I loose steps (some 6.7KHz). Reducing period to 15uSec, and the maximum speed increases to 30ipm. [Sherline uses 16000 steps per inch when using their driver box]. Hooking up a scope, I see a pulse train right up to 240ipm or 64KHz with a 7.5uSec period. There is a fair bit of jitter which could explain the lower max speed. At 15uSec, the pulse train is much smoother with little noticable jitter, but maximum frequency is limited to 33.3KHz. I would suggest hooking up a scope if you can get your hands on one, quantifying the jitter and selecting a period to suit - I can run at 7.5uSec, but jitter is a problem, the same at 10uSec. 15uSec produces the better results when using quickstep, but your milage may vary. Regards, Paul. -- From the Klingon book of C: Klingon function calls do not have 'parameters' - they have 'arguments' - and they ALWAYS WIN THEM.
Paul, Thanks for doing some testing on your mill. It never occurred to me that increasing the Period would produce a smoother pulse train. I had reduced it a few days ago to 7usec to get rid of following errors. I did play around with it set at 10usec this morning but I didn't see any improvement, it seemed like I could hear more jitter coming from the motor. I have a big old HP digital scope upstairs I have to try to bring downstairs to test the setup. I'll be happy if I can get smooth 25,000 steps/second. Is there written instructions somewhere and the proper steps to download/install latest emc packages using apt-get? Regards, Jim
Dug out my little Sherline and ran a few tests this morning. The computer is a Celeron 433 with a 440BX chipset, and a C&T 69000 graphics controller (2MB memory running at 800x600), currently with 256M of memory installed. Probably close enough in specifications to do a reasonable comparison of EMC's performance..
The stepper motors on the Sherline are fairly wimpy little NEMA23 rated at 134oz-in running from a unipolar driver - Not the best combination for maximum performance.. About the best I can achieve is 25ipm with a 7.5uSec base period before the motors start squawking and I loose steps (some 6.7KHz). Reducing period to 15uSec, and the maximum speed increases to 30ipm. [Sherline uses 16000 steps per inch when using their driver box].
Hooking up a scope, I see a pulse train right up to 240ipm or 64KHz with a 7.5uSec period. There is a fair bit of jitter which could explain the lower max speed. At 15uSec, the pulse train is much smoother with little noticable jitter, but maximum frequency is limited to 33.3KHz.
I would suggest hooking up a scope if you can get your hands on one, quantifying the jitter and selecting a period to suit - I can run at 7.5uSec, but jitter is a problem, the same at 10uSec. 15uSec produces the better results when using quickstep, but your milage may vary.
Regards, Paul.
--
From the Klingon book of C: Klingon function calls do not have 'parameters' - they have 'arguments' - and they ALWAYS WIN THEM.
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Hi Jim On Saturday 04 March 2006 18:31, Jim Fong wrote:
Is there written instructions somewhere and the proper steps to download/install latest emc packages using apt-get?
You have a BDI-4.38 install - The repository entries in /etc/apt/sources.list will have most of the current URLs.. You might want to add: deb http://bdi4emc.ourproject.org/debian sarge extras non-free This will usually get any updates several hours before the other two repositories that host the EMC packages. Updating from the command line is a simple:: sudo apt-get update sudo apt-get install emc emc-modules-2.6.12.6-rtai Alternatively you can use Synaptic and get it to show upgradeable packages and use the point'n'click interface. Regards, Paul. -- From the Klingon book of C: Klingon function calls do not have 'parameters' - they have 'arguments' - and they ALWAYS WIN THEM.
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