PWM and Mesa 5i20, question for encoder feedback

[fomaz]

Hello,

Just ordering a 5i20 and a 7i33TA for testing EMC2 for servo speed control, when I realized that my servo drives accept digital (3 to 5V) PWM and also analog 10V.

1) This means that I can directly connect the 5i20 outputs to my drive, not needing any other daughter board for motor control (do not need the 7i33TA that is for analog control)?
2) The encoder feedback, mounted on the servo, for closing the loop on EMC2, that passes trough the servo drive, will also be connected directly to the mesa 5i20? Encoder is incremental differential output 5VDC.

There are any other considerations about this set up that I should be aware of before ordering the mesa hardware? I live quite far away from the supplier and ordering something can be quite a trouble.

Thank you.

[PCW_MESA]

Originally Posted by fomaz Hello, Just ordering a 5i20 and a 7i33TA for testing EMC2 for servo speed control, when I realized that my servo drives accept digital (3 to 5V) PWM and also analog 10V. 1) This means that I can directly connect the 5i20 outputs to my drive, not needing any other daughter board for motor control (do not need the 7i33TA that is for analog control)? 2) The encoder feedback, mounted on the servo, for closing the loop on EMC2, that passes trough the servo drive, will also be connected directly to the mesa 5i20? Encoder is incremental differential output 5VDC. There are any other considerations about this set up that I should be aware of before ordering the mesa hardware? I live quite far away from the supplier and ordering something can be quite a trouble. Thank you.

Yes its possible to use the FPGA inputs (like encoder pins) and outputs
(like PWM or STEP/DIR pins) directly if you wish. There's an obvious cost advantage of doing this but there are a couple of disadvantages:

1. You have only 3.3V signals from the FPGA
2. A connection mistake is costly as you can fry the FPGA
3. RA-422 differential signals are not supported

If you want to use a daughter-card for digital PWM interfaced drives, I would suggest the 7I52S. This daughter-card will give you 6 single ended or differential encoder inputs and 6 5V PWM/DIR or PWM/ENA or STEP/DIR pairs (also differential if your PWM inputs can accept that but useable single ended as well)

[fomaz]

Thank you,

Then is clear that I need a daughter-card.

As drives accept both the analog and digital, my final issue resumes to:

7i33TA or 7I52S

There is more people using the 7i33TA for what I have read. There is a clear advantage in using the 7i52S over the 7i33TA? I am afraid of ending in a non support situation, where more people normally means better result...

Thank you

[PCW_MESA]

Originally Posted by fomaz Thank you, Then is clear that I need a daughter-card. As drives accept both the analog and digital, my final issue resumes to: 7i33TA or 7I52S There is more people using the 7i33TA for what I have read. There is a clear advantage in using the 7i52S over the 7i33TA? I am afraid of ending in a non support situation, where more people normally means better result... Thank you

Yes the 7I33TA has been out for years and there are more than 1K retrofits using it so its more of a known quantity. The advantage of all digital is perhaps a little lower cost and perhaps better noise resistance (though this depends a lot on the analog and digital interface design of the drive)

Using the 7I52S has the disadvantage that you need EMC2.5 to support it
and its fairy new territory especially if your drives use locked-antiphase PWM
instead of PWM/DIR (in locked anti-phase 50% PWM = 0 drive)

[fomaz]

Thank you.
Order was made in your Europe distributor.