Topics

21

Modbus / Does MACH have Modbus monitoring . . i.e. a way to see if Modus is running OK?

« on: May 07, 2012, 06:56:49 AM »

Trying to find a way to notify user if modbus connection dies for any reason.

Docs on MACH's modbus implementation are sparse and I don't find any way to query MACH for Modbus status.

The application is to be able to E-stop MACH from an external source if the Modbus com stops for any reason.

If it is not possible to query MACH, then what methods are people using to monitor the connection?

A character could be sent and retrieved by the slave and a hardwired signal used to notify the user of a problem, but it seems there should be a way to query MACH.

22

General Mach Discussion / Mach BUG in xx.50 skip line after sub is back.

« on: October 21, 2011, 05:49:03 PM »

Old bug has returned.

Also check the thread on Cutter comp for description of another bug in that function.

23

General Mach Discussion / Differential Signal Converter board DIY freebee G-code included

« on: February 12, 2011, 04:07:25 AM »

By request here is a freebee for anyone who needs a differential signal converter board or just wants to mess around with routing a PCB for the fun of it. Traces are best cut with a 30 degree engraving bit at a DOC of only a few thou. then .032" drill and .047" drill. Componets are listed on the drawing. Rev1 does not use terminal blocks. It is meant to have the wires soldered to the board andthen have the whole thing encased in tape or heat shrink and become more or less part of the cable.

No warranty express or implied. Use at your own risk. Routing PC boards is fun and can be addictive. Links to G-code set is at end of post. Setting up a little mill to do engraving is as easy as mounting a die grinder on the head like this:

http://www.youtube.com/watch?v=r9Zf_5yHB1I



www.thecubestudio.com/DifferentialPCB/DifferentialTracesRev1.tap
www.thecubestudio.com/DifferentialPCB/DifferentialDrill032Rev1.tap
www.thecubestudio.com/DifferentialPCB/DifferentialDrill047Rev1.tap

24

General Mach Discussion / Question on using DC chokes on SCR drives

« on: August 28, 2010, 06:25:06 AM »

In anticipation of using a larger spindle motor, have switched from a PWM drive with separate relay reversing to a big 4 quadrant regen SCR drive that has reversing built in.

Being spoiled by the smooth PWM power, I am not satisfied with the much coarser SCR performance and have been doing some research on adding a driver or choke to the output and perhaps also a filter on the AC input. I have been able to find only references to using two legs of a very expensive 3 phase reactor filter as a choke between the drive and the motor, but I can get a plain 10A choke for 1/10 the price of the reactor.

Question: with a reversing drive, do I need a choke on each DC wire to the motor or will one choke suffice?

Question: is there any tangible benefit to adding a line filter on the A/C input to the drive relative to motor low speed smoothness?

25

General Mach Discussion / RPM readout showing negative numbers . . suddenly . . . WTF??

« on: August 18, 2010, 05:08:48 AM »

I did a search on this and have not found and answer, but I am sure it must be something simple.

Currently I am  installing Mistubishi industrial AC servo drives and therefor have beed tinkering around in the control box and reconfiguring Mach, but I did not change the BOBs  nor any of the sensors or wiring related to the spindle speed. I don't know when the RPM readout went south so I can't say exactly what I was messing with that affected it.

The signal from the sensor shows strong and clean on a scope and the BOB has indicator LEDs  that are flashing regularly as the spindle rotates. The readout is not only negative, but the readings are low  . . no pun intended . . for example it reads -750 when the spindle is actually running about 2,000 RPM. The readout does change and follows the spindle speed, albeit inaccurately.

26

General Mach Discussion / Servo Drive Review - Granite VXD-XE added. New TOP CHOICE drive.

« on: June 24, 2010, 08:27:06 AM »

Since the original review was done, the granite Devices VSD drives have undergone significant upgrades which brought the product into competition with the Dugong drive. Additionally, new firmware allows the Granite drive to control two motors (DC brush) which also makes the product price competitive with the lower powered drives.

I have had a continuous stream of requests to look at the Granite Devices product, but until the drive was further developed, it was not suitable for my application, and was too expensive to just purchase and review as a 'favor' to people.

Two issues have converged to make the Granite drive not only attractive, but necessary for my application. First was a very significant upgrade in the drives specs to 160V 40A. Second was CNCdrive's inability to add the needed features to the Dugong.

My 4th axis project has been at a standstill for months now waiting on promissed new Dugong features. With the Granite drive already having the feature set I need and now with the higher power that I also need, the higher cost of the Granite drive was more palatable.

Here is the link to the review: http://www.thecubestudio.com/ServoDriveReview.htm

As it turns out, while I was mostly interested in the feature set of the Granite drive, the exceptional performance alone would easily justify the higher cost in some applications. The same features that make the VSD suitable for the 4th axis also make it suitable for a servo powered spindle, either for a mill or a lathe. On balance, below are two excerpts from the updated review which summarize my findings:

UPDATE: 06/24/2010: the Whale3 remains the ”BEST CHOICE” among the smaller (100V/20A or less) drives in this lineup, but after adding and reviewing the recently upgraded Granite VSD-XE, it is now the TOP CHOICE .

While the Ganite VSD-XE is my TOP CHOICE for this review, that choice is weighted heavily with performance and features of the VSD-XE that the competing products simply cannot match in their current configurations. However, users requiring a 100+V/35A drive who do not need the features of the Granite product, and are not gong to use step multipliers, would most likely be happy with the less expensive previous winner, the Dugong from CNCdrives in Hungary.

27

General Mach Discussion / Combining grounds of 12VDC logic and linear unregulated HV

« on: May 17, 2010, 05:06:20 PM »

I'm sure this has been asked before and I have done searches and read what I could find, but still I am confused a bit by the options.

I my setup, 5VDC and 12VDC are supplied by a standard PC power supply which is grounded to the control box chassis.

HV is a toridal linear unregulated PS with 72VDC output which is not grounded to the chassis.

Voltmeter says no continuity and no voltage between 72V + or 72V- and chassis.

I now need to supply a drive with 12V and HV that have a common ground.

What are the options and what is the best way to do this?

28

General Mach Discussion / Need Guru input on an idea: Using Mach as dynamic balancer

« on: May 13, 2010, 12:10:49 PM »

I am looking at acquiring the capability to do some simple dynamic balancing, and I need some help from the electron guys who are also familiar with Mach scripting.

A very simple form of dynamic balance is simply a sensor (accelerometer) that triggers a strobe light. The light is pointed at the spinning object and similar to a timing light, the strobe freezes the part at a specific point. You throw on some weight and go thru "worst/better" iterations until the balance is close enough. Not efficient, but it does work if you have the time and patience.

A new USB based balancer that runs on a laptop is over $6,000 and has capabilities far in excess of what I need, so I am looking at DIY (read cheap) alternatives. Basically, all that is needed is to fire a strobe based on movement (vibration) of the part.

First, are there any oscilloscopes or other off-the-shelf devices that can do this?
Second, how difficult would it be to design a circuit to do this?

Third, it occurs to me that Mach can take an input (tachometer) and of course can generate outputs. I think I can figure out how to fire a strobe from a 5v output pin. How would one go about connecting a digital or analogue accelerometer to Mach as if it were an index? And can the index input signal be detected by script?

29

General Mach Discussion / Question for anyone with 'enable/disable' capable servo drives

« on: March 18, 2010, 03:44:35 AM »

A couple of guys on here said they have servo drives with an 'enable' pin that kills the power side of the drive and yet keeps on tracking the encoder.

My question is; what does the drive do when it is re-enabled after a disable if the axis was moved during the disable?

If the axis was moved, does the drive consider the new position to be OK, or does it try to immediately return the axis to the pre-disable position?

30

General Mach Discussion / What is a good probe to use with Mach?

« on: January 19, 2010, 03:06:45 AM »

Now that I have an accurate machine, I am considering taking the plunge to probing/digitizing.

Wondering what people are using and how they like it.