Convert from Anilam Crusader M to EMC 2

cmorley wrote: Ahh yes the red one. This is definitely square wave TTL output. I have some of these. I just can't remember the resolution.
IIRC the color is a clue of the resolution (red orange and green I have)

While TTL output means it's easy to connect to, it also means you can't improve the resolution - aside from replacing them.

Chris M

Chris, the info I found shows that this is a 10 micron (.0004") encoder. From reading through other threads, it sounds like some have had difficulty tuning EMC with this "coarse" of an encoder. I do like the fact that it is measuring true position, and thus reducing the impact of backlash somewhat. Any advice regarding the likelihood of success with this resolution?

Ryan

Well I don't have a lot of practical experience. I did some testing with a linear encoder only but it was a much higher resolution.
It was a heidenhain analog sine wave output that could be interpolated ( 5 fold in my case )

From what I have read a rough rule of thumb is minimum 5 times finer then what resolution you want.
Bottom line is You have it so try it. You always add encoders to the motor or ball screw later.
Hopefully you have very minimal backlash. Backlash will be more of a problem with the linear encoder then the resolution I think.

Other with more experience will surely advise you soon....

Chris M

cmorley wrote: From what I have read a rough rule of thumb is minimum 5 times finer then what resolution you want.

Do the motors have tachometers?
The LinuxCNC PID component has in input from a separately-derived velocity pin. It ought to be possible to drive that via an analogue-to-digital stage.
The 7i77 has the option to use some pins as low-resolution analogue inputs.
You might have to do something excessively cunning such as derive high-speed data from encoder count delta and low-speed velocity data from tachs and A to D, with HAL arbitrating the switchover. (simple addition it probably fine, with the scales correctly set)

andypugh wrote:

cmorley wrote: From what I have read a rough rule of thumb is minimum 5 times finer then what resolution you want.

Do the motors have tachometers?)

Yes

I do like the fact that it is measuring true position, and thus reducing the impact of backlash somewhat

Good point, however it was my understanding that using linear scales with an axis that does have too much backlash would make the servo tunning difficult, which was the reason to add encoders.
Perhaps Andy is onto something with the tach signal.

Rick G

andypugh wrote: The 5i25 / 7i77 combo might work better for that conversion now, though the 5i23 / 7i33 setup used there is still good and potentially more adaptable.
(I have a 5i23 in my milling machine, and I am using a wierd mix of hardware, resolvers, encoders, smart-serial)

Guys, I will address this question to the Mesa guys, unless you have this information readily available, but why is 5i23 / 7i33 more adaptable?

Why the 5i25 / 7i77 if I will never use 6 axis, why not 5i25 / 7i33?