Arduino Leonardo and linears encoders.

Hi everyone, first of all sorry for my english, i´m spanish and you know...

I have retrofit a manual mill using linuxcnc as control, it works great! Now i want to do a Pendant to aproximate the mill and set zeros to the axis. I have been testing with a joypad and it works too. But i want to make my own pendant with an arduino. The thing is that recently is been released a new version of arduino called Leonardo, i have read that this new version works better and have more digital I/O. I´m no informatic and my knowledge about programming is not very impressive, so my question is if i buy a Leonardo will i been able to program it with the same sketchs of the Arduino One?? if i have just to change little things doesn´t mind....

Other thing i want to do is to make a closed loop with linear encoders, actually my system is been done with servos, they have his own closed loop, but i want to read the real position of the tables with linears encoders. The linear encoder chosen by me is the mitutoyo AT 216 T.

pdf.directindustry.com/pdf/mitutoyo/scale/4906-14503-_6.html

In this PDF, in page 6 and page 14 are related its features. Do you know if this linear encoder will fit with linuxcnc??

Thank you very much!!

Thank you for your answer, i´m going to buy a Leonardo and test if i can manage.

The resolution of the encoder is 5um = 0.005 mm.

Mi machine speeds up to 1000 mm/min more or less, it has encoders with 2000 pulses per revolution, and each pulse moves around 0.00035 mm.

Is still being a good choice the mitutoyo AT 216T??

Im using parallel port, but in the future when i put the 3 linear encoders i´m going to need more digital inputs so i think i will have to but a I/O card, can i have usable I/O inputs with an arduino connecting it to the paralel port instead USB, o i need to buy a MESA card or similar??

Thank you very much.

Hi

Other thing i want to do is to make a closed loop with linear encoders, actually my system is been done with servos, they have his own closed loop, but i want to read the real position of the tables with linears encoders

Im using parallel port, but in the future when i put the 3 linear encoders i´m going to need more digital inputs so i think i will have to but a I/O card, can i have usable I/O inputs with an arduino connecting it to the paralel port instead USB, o i need to buy a MESA card or similar??

Whilst I am a fan of Arduino boards you just have to accept their limitations. You are potentially talking about 6 encoders here.

The set up you are talking about would be far better served by using the Mesa cards that are designed to handle encoders, plus all the other inputs required.

The only way you could use an Arduino with a parallel port that I can immediately think of, would take a LOT of wiring and probably most of its IO just to implement, for what purpose - simply to use an Arduino?

regards

Hi! Thanks for the asnwer. At the begining i thought to make and arduino Pendant just for aproximate the mill and preset zeros, but reading posts i started to think about using an arduino as I/O card, just for having more digitals I/O to fit the linear encoders. What i don´t know is if the Mhz of the clock of the arduino will be enough or similar to Parallel Port, or even similar to a MESA card.

My system will have 6 encoders, but just 3 will "talk" to Linuxcnc, the other 3 ones will be part of the closed loop that the Drivers-Servos make. And linuxcnc doesn´t mind about that closed loop.

To make this system ( 3 axis with linear encoders) which MESA card do you recomend me or another brand that works fine with linuxcnc.??

Thank you very much.

Thank you for your answer.

Sorry for the time to response, i´ve been looking the options you have suggested to me.

I explain you what i have and what i want. My system is based in servos, but this servos are digital and they just work with step/direction inputs. Right now i don´t have linear encoders, but my idea is put one for each axis (X, Y, Z). Right now i do my digital outputs with the paralell port of the computer, but the number of digital inputs (for the linear encoders) is low, and i can´t reach the total of digital inputs i need with the paralell port. I want to put too limit switch´s for axis, but i think with one digital input it will be enough ( for the 6 limit switch´s) .

The linear encoders i´ve seen on internet is Mitutoyo 216 T

pdf.directindustry.com/pdf/incat/216-t-4906-14503-_14.html Page 14.

Those linear encoders are incremental digital, they have two digital outputs to read 2 phase cuadrature signals, i think they will fit with linuxcnc but i don ´t really know.

So making a recount what i need is:

Digital outputs -> 6 ( 2 per axis for step/direction)
Digital Inputs -> 7 ( 2 per linear encoder, one per phase and 1 to the switch limit )

I would prefer to have more I/O digitals for if in the future i want to put more things.

Do you think the combo 5i25 + 7i85S it will be suitable or is preferred the 5i25 + 7i85S + 7i75?? The money is not a big issue.

I havent been able to see the pico characterics in the web. My english is very poor. Sorry

A lot of thanks to you. This helps me a lot.

Regards.

I´ve been reading the datasheet of my drivers (for the servos) and i think they have only the digital option to recieve the input signal. They are Smartstep form Omron:

industrial.omron.es/es/products/catalogu...artstep/default.html

Ok, actually my system works with step/direction signal output from linuxcnc to the drivers, and they are who do the closed loop(with the rotary encoder that the servomotor has). Linuxcnc just don´t mind about the closed loop, because it is done by the drivers. Linuxcnc works just as an emitter of pulses, but it doesn´t recieve any information from the movement.

Ok, so now i want Linuxcnc recieve information of the movement with another extras linear encoders, leting linuxcnc to make a closed loop ( Pulses sent to my drivers, and pulses recieved from the linear encoders). I Think doing it like this i will have 0 error (talking in 0.01 mm) in the position. Right now i have more or less 0.02 mm of error due to the mechanichs.

The problem here is i´m going to have 2 closed loops, one from linuxcnc ( linear encoders) and one from Smartstep (rotary encoders). But it should not to be a problem since linuxcnc is only going to manage and have knowledge of one closed loop ( linear encoders). Of course i have to calibrate the accuracy of one pulse in my servos to the accuracy of the linear encoder for not creating a infinite bucle.

Working like this linuxcnc is going to work with a normal configuration of step/dir and linear encoders feedback, isn´t it? Like Step by Step motors.

I´ve been reading and i think the configuration 5i25 + 7i85S + 7i75 is the best choice for me, but i have doubts. In the page of mesa www.mesanet.com they say that the 7i85 card allows linear encoders inputs in TTL o RS-422. Are that inputs suitables for the encoder mitutoyo 216T i put two threads before??

Another thing is you know if mesa works with europe, i have sent them an email with my doubts but they haven ´t response me.

Again, a lot of thanks!!

Regards.