Advanced Search

Yes, I tested this before, but it did not make a difference in the result

besriworld wrote:

This board is not good for high speed step/dir . 
For reliability you need differential signals. 
It is also important to have a nice layout for the input signals.

 

Everything works perfectly! No problems whatsoever!!!

is the serial pin header on the 8i20 isolated? Which header is it, the one on the right side of the PCB i assume?

No it doesn't shutdown the pc only linuxcnc exits i have debian12-xfce
exception not thrown in case of missing gnome-session-quit but this is minnor
The other error message seems more serious.

Ethernet/Ethercat does not have sufficient isolation for line powered devices
so the original 8I20 architecture with serial interface to a torque mode drive
does make some sense.

Another way is to use isolated gate drivers and say a AMC130M02 for current sensing...

PCW wrote:

On card with a ground plane SPI is fine. Between cards in a motor drive
with volts of ground bumping  and clock signals that are susceptible to 10 ns
spikes would likely require isolation. Isolation is a bit fussy for SPI because it needs
3 or 4 pins and skew is important (a good reason to use serial instead)
Its certainly possible but unless you had a good reason to do it, its probably not
worth the trouble.


 

EtherCAT!!!!

Now that I think about it SPI wouldn't do any good anyway. I doubt you could have that PIC do the things it's currently doing and be the EtherCAT application processor as well. ESC would likely have to connect to a dedicated MCU on that PCB then yeah maybe that MCU could just interface the 8i20's PIC over serial.

I haven't put a ton of thought into it, I just saw my 8i20 and said "wow that's a cool idea". Does the current serial protocol/ firmware etc facilitate the purpose of the Unicorn board that may or may not have turned it into a velocity mode drive?

Isn't all of that "User interface" though? That section is obviously dedicated to *Graphical* User Interfaces but if you think about the fact that everything you interact with on anything you consider an "HMI" is either a duplicate, or replacement, or facilitates the graphical user interface....isn't that where HMI and all the other stuff mentioned above really belongs? Maybe split out a sub forum for hardware user interfaces or something

On card with a ground plane SPI is fine. Between cards in a motor drive
with volts of ground bumping  and clock signals that are susceptible to 10 ns
spikes would likely require isolation. Isolation is a bit fussy for SPI because it needs
3 or 4 pins and skew is important (a good reason to use serial instead)
Its certainly possible but unless you had a good reason to do it, its probably not
worth the trouble.

 

PCW wrote:

A single turn absolute encoder will read the correct angular shaft
position at power up.

 

From the DYN4 manual regarding the "Absolute Encoder" equipped Servo

The motor power on position is the default absolute zero position, or it is the position set by using set absolute
zero function (0x00).

That sounds like the behavior of a purely incremental encoder. Now if you stick an ASIC inside the encoder housing that does the actual counting, maybe you can get away with calling that servo encoder "absolute". If you stick a battery on it, power on no longer affects it's so it's semantically the same thing as a physically reading absolute encoder except for the fact that when it woke up the absolute position was not physically predefined.

The only way to reset the drive position on a DYN4 is to hard reset the CPU. I'm guessing that hard reset drops the encoder power and allows it to reset as well. That sort of backs up my theory about it being a mostly incremental encoder with an ASIC processor I think. I'm not really smart enough to get into all that commutation business but I don't see how their standard motor encoder resembles an absolute encoder in the traditional sense.

I make those points because I'm assuming the converter is based on the same ASIC and basically does the same thing.

PCW wrote:

SPI is not a great off board interface to line operated power devices...
 

What's the concern using SPI in a board to board configuration on something like an 8i20 that's powered off a DC bus of the user's making? the 8i20 isn't really scared of isolators so I'll get the obvious out of the way and I assume that motor driver doesn't spray too much EMI all over the transmission lines cuz it looks like a PIC sits right on top of it.

It's a hypothetical question anyway since it doesn't actually exist but what problem couldn't be overcome with a little consideration on either side?

Kind of a moot point but the STMBL has an SPI header on it, for whatever that's worth.
 

Have you tried:

HOME_INDEX_NO_ENCODER_RESET = YES

in your ini file?

Thank you for that adjustment, axis itself allows loading files without activating the machine.

Going back up the stack of things I asked... regarding the reload button you asked if I had a pref file path set

First, I do not, but verbose mode saysThat file does exist and contain the preferences, so I think this should be working fine.

Second, if I set the value without a full path likeqtvcp does not like that and fails to start with
Stack trace   in case you'd like to examine this.

Well, it is not a delay in the quadrature output, but a delay in responding to changes in velocity. Apparently, that upsets servo loops less than just plain position delay,
Jon

Thank you for the explanation it makes sense to me now.