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Author Topic: Error Download Encoder Polarity. Download Aborted.  (Read 3970 times)

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Error Download Encoder Polarity. Download Aborted.
« on: February 17, 2011, 12:37:36 AM »
Hey Guys,

Just recieved my DSPMC with firmware Rev7762/6.25 and Plugin M3dspMC.dll.
I have set-up the Mach 3 interface and integrated the DSPMC by copying the .dll file into the Mach 3 plugin folder. I have attached the DSPMC to Mach 3 via the ethernet port and router and it is showing that it is connected. No equipment is attached to the inputs/ouputs however i thought it best to test the analogue signals +/- 10V before doing so. I have followed the instuctions outlined in the set-up manual to a tee, however an error message keeps popping up that states; Error Download Encoder Polarity. Download aborted. & Error downloading config data. Retry?  ???
This error comes up intermetantly every 10 seconds and triggers an emergency stop, thus ceasing functionality of Mach 3. Will these error messages cease once encoders are attached? Or is there something I've possibly overlooked.
Also, we have a total of 7 encoders on our machine. 4 from the servo drivers and 3 for axis. Mach 3 only supports 4 encoders. Will i have to write brains to integrate the other encoders as inputs on the digital I/O board? Mach 3 also only supports 2 channel encoders whereas the servo driver encoders have 3 channels.
A similar problem was experienced by member "dresda" however a solution to the errors was never discussed.
Any help that anyone could offer would be greatly appriciated.

Thank-you in advance to everyone.  :)
Re: Error Download Encoder Polarity. Download Aborted.
« Reply #1 on: February 18, 2011, 11:41:38 PM »
Greetings Neyland:

The Mach3 program does act strangely when nothing is connected. Once you get the encoders connected, and the analog signal going to the servo amps, things will settle down. It is tempting to make something happen you can see visually, before all the various components are hooked up. I did the same thing.

Make sure your units are set correctly. Inches or millimeters. There are several places where this is referenced. Motor Tuning, Home Limits etc.

Set-up the encoder counts/rev in the Motor Tuning section of General Config…. , and then the parameters for the PID numbers are set in the screens when you click the plug-in section.  Config; Config Plugins; Config (Plugin name: M3dspMC-dspMC-Plugins-3.12-Vital-) Click the yellow box, and the Plug-in screen configuration will come up. Each axis will have it's own screen under a tab.  PID settings are saved to the dspmc, as well as to the Mach3 XML for that particular named setup.  This is where all the motor tuning happens.
 If an axis is not enabled under Ports and Pins, it will be dimmed out in the Motor Tuning.  Enable the axis motors in Ports and Pins, set to active LOW.  There are boxes for accel and such, but the only ones that matter are the encoder counts/unit, and the velocity  in/min to make things move.
May I suggest doing one axis at a time. Connect the power to only one axis, and get that one moving, start/stop under the plug-in screen for that axis.  Get all the tuning, encoder counts, and various  parameters OK. There are lots of little settings, but once one is working smoothly, you can copy the settings to the others one at a time.

Regarding you question about encoders, the dspmc can read (6) encoders, 3 channels each. Look at the Vital System manual regarding J6, J7 Pin Assignments. For J6; Channel 0 = X, Ch 1 = Y, Ch 2 = Z. For J7; Ch 3 = A, Ch 4 = B, Ch 5 = C.  The (6) encoder count does not include the inputs for MPG's, on J4, J5, which are a separate kind of device.

For example, on J6, The X axis is called Ch 0, and it has connections for A+, A-, B+, B-, Z+, Z-, 5v., and ground. A and B are the two counting channels, and Z is a once per rev index channel. There should be 5 wires per encoder. Use quality shielded wire for connecting the encoders, and analog signals, and keep the colors uniform for the channels.

 On my machine, which was a factory built 4-axis CNC which I am retrofitting with the dspmc, Channel A+ is green, channel B+ is red, channel Z+ is white, +5v is blue, and ground is black. They also had a separate ground wire for each axis, A-, B-, Z-, which was set up as a pair for each channel; A+ and A-(ground) twisted together, and was encased in it’s own foil wrap, etc.  At the business end, I connected all the grounds to 1 wire.  This might seem like overdoing things, but I never had a glitch due to noise. I am not sure you can even get wire of this quality anymore.  If a motor goes the opposite direction you want, it can be reversed in the Homing Limits tab. Don’t start switching A & B around.

You can make the axis motors move without completing the home /limit switches. However, once an axis is tuned, and moves good, work on the home switches, and Z channel index home feature working properly. 

It takes some patience and time, when starting to tune an axis. The starting PID numbers are a ballpark in the Vital Systems manual, but should get something moving. In the plug-in screen, you can move a specific distance, and see the encoder count, and the motor acceleration curve on the graphic screen. It is a really slick way to tune your motor settings. Once things begin to get moving, you will feel a lot more positive about the process.  It is all very logical and well defined, and a lot of engineering has gone into the dspmc controller.

Don't confuse some of the references in the Mach3 manual, and the dspmc manual.  It takes several readings of it all to make sense, and sink in. The dspmc manual makes clear the specific Mach3 input pin numbers relative to the dspmc I/O boards.

One last warning. Be careful with the I/O boards.  The 7535 is fully opto-isolated, and can take up to 30v dc., but the 7711 is not. I accidently put over 5v to the wrong terminal on a 7711 board, and damaged my dspmc when first wiring things up.   

Hope this is of some help.
Regards, John