Messages

361

SmoothStepper USB / Re: SmoothStepper and PLC with Modbus

« on: November 21, 2011, 08:51:25 AM »

The motor control is made by Mach3 and all the rest is made by a Fatek PLC. I feel it's more reliable and safe to dedicate a PLC to control limits and estop because it's closer to the energy that way.

My friend you are simply wrong. Your EStop circuit should NOT depend on a PLC, the SS, the PC, etc to run correctly. You have in fact made your system more unsafe by using your PLC to control your EStop.

Also, the limit switches MUST be tied directly to the motion control device. You cannot run them through modbus as there is too long of a delay in the signal reach Mach.

362

General Mach Discussion / Re: It's Alive! (El Cheapo Dyna 2400 Mach III conversion)

« on: November 19, 2011, 04:21:50 PM »

I got an email the other day after somebody read this thread. Just a quick update:

I recently re-updated this machine to a G540. WOW! what a huge difference. The motors and power supply are stock, but I ripped out the old stepper drives and a G540 dropped right in the same location. It is like a whole new machine, running 40IPM rapids even with 101,600 steps/inch (thinks to the SmoothStepper putting out such a nice pulse train.)

I'll post some pictures soon.

363

SmoothStepper USB / Re: Issue with Mach XML And SmoothStepper

« on: October 21, 2011, 11:26:21 AM »

It sounds like your original XML file may have been locked or had its write permissions altered (you created the file with admin credential but now you are logged in as regular user or something similar). When this happens Mach won't be able to write to the file properly so it just creates an all new one without telling you anything about it. Maybe Andrew can send you the profile of yours he changed over to the SmoothStepper?

364

SmoothStepper USB / Re: Smoothstepper - Endless Loop

« on: October 19, 2011, 02:39:03 PM »

The problem is that the SS plug-in perceives loosing communication with the SS as a show stepping error, which in truth it is because there is no good way for the SmoothStepper plug-in to reset itself to Machs current state (a limitation of how mach deal with external motion control devices.) So you have to restart Mach so it and the external motion device can get back in sync.

It would be nice if the error messages were limited though.

365

SmoothStepper USB / Re: "time out error getting data" wtf

« on: October 07, 2011, 02:51:34 PM »

Usually this is because Windows is turning off the USB port. Go to: http://www.soigeneris.com/Documentation-content.aspx and look for the SmoothStepper section and download the installation tips. It will tell you how to disable the automatic power off 'feature' from WinXP.

366

SmoothStepper USB / Re: Help! Servo turns CW only with SS

« on: October 04, 2011, 10:38:28 AM »

You need to measure the voltage at the direction pin on your BOB first. This will tell you where the problem lies.

367

SmoothStepper USB / Re: Help! Servo turns CW only with SS

« on: October 03, 2011, 08:24:18 PM »

Sounds like you are missing the direction signal. Could be a configuration issue in Mach or it could be a wiring issue. Use a volt meter to measure the voltage on the direction signal, it should change from around 0V to around 5V when you change the direction your jogging.

368

General Mach Discussion / Re: limit switch accuracy

« on: September 25, 2011, 12:23:00 PM »

This one with 1um accuracy is about £63.00

You have to be very careful when reading a data sheet, it does not say  '1um accuracy', it says 'switching point sensitivity' (which is what?).

I've attached the mechanical specs of the switch below. Its repeatability is shown as +- 0.001mm with hysteresis of <= 0.002mm. While these are still impressive sounding numbers the typical well adjusted machine might have backlash as low as of 0.01mm, add in less than perfectly clean activating surfaces, temperature changes in teh machine ,etc and the 'real world accuracy' of even a precise switch like this starts becoming less clear.

I'm not wanting to be a negitive nellie but rather want everyone to get the 'whole picture'. There are many factors involved and you can't just fixate on impressive sounding numbers from one sensor/switch and ignore the rest of the system.

369

General Mach Discussion / Re: limit switch accuracy

« on: September 23, 2011, 09:58:13 AM »

I always like questions like this as the accuracy of the system in general is probably more important to know.  

have a repeat accuracy of better than 0.001 mm

Is that really the manufactures specification?  It is quite deceptive of them. Under what conditions would such a rating be true. That is about 4 hundred-thousandths of an inch. If you breath on it your likely to heat it up enough to change the reading not to mention how the reading will change as the machine itself heats and cools. A speck of dust in around 0.00002" so if the sensor or actuator is not perfectly clean then your reading will be an order of magnitude off (gasp only good to 4 ten-thousandths of an inch).

A typical mechanical switch will vary a bit in the exact position it opens and close due to several factors. The spring loaded parts inside will react slightly differently with temperature changes. The contacts also don't instantly change from open to closed (or closed to open) they 'bounce' a little so which of these bounces is Mach likely to see?

Think of the switch contacts as a resistor, when the contacts are closed you have close to zero ohms of resistance, when open the contacts have nearly infinite resistance. As the contacts start to open the resistance starts to rise every so slightly. Witch a good contact design this resistance change is fairly accurate and expensive contact probes look for this change is in resistance which provides a more repeatable indication that the switch is opening.

Back to the job that the OP is trying to do. You may find it is more accurate to move until you contact the switch and then back off of it really slowly.

370

SmoothStepper USB / Re: MACH CAN NOT COMMUMICATE WITH SS

« on: September 08, 2011, 06:57:45 AM »

Since I have no idea how you rewired things I can't really make a suggestion. It could be that your PC and control cabinet have different ground potentials. I have also seen many time when people say they grounded everything they literally run a ground every DC Common to earth ground, or have actual control circuits running through earth ground. Maybe you can post some photos of your control cabinet?