Mesa 5i20 -> 7i42a -> 7i47s -> geko 203v X3

Hello, I am new to all of this linuxcnc (and cnc in general stuff), and so far I am really enjoying my learning project. What I am looking for is a little confermation that my setup will work and help chosing which firmware in pncconf I should use.

I have a 5i20 in the computer which is connected to a 7i42a which is connected to my 7i47s which in turn is connected to my gecko 203v's which power 3, 600oz/in steppers.

So first off, does this setup make sense? it seams reduntant to me, shouldn't I be able to send a step signal right from the 5i20 to the 7i42a and not need the 7i47s?

second what firmware should i chose in pncconf for this setup. One of the firmwares has 7i47 in the name, but its pin options under i/o config do not match up at all with the manual from mesa?


Thanks for any help

Theres no reason to use a 7I42 and a 7I47 together. Each should be used individually,
one per FPGA connector.

There are a couple of 7I47 compatible configurations, one being the SVST2_4_7I47. This has 4 STEP/DIR pairs, 2 PWM/DIR pairs and 4 encoder inputs. I would suggest using the 7I47 rather than the 7I42 because it has 5V buffered outputs.

Thanks, thats really helpful.

I am now trying to make my stepper spin just as a test. In pncconf after I have selected svst2_4_7147 and under i/o connector 2, how do I know which of the functions connects to which pin on the 7i47s?
ie: I can pick which ones I want to be step gens and encoders but they give no indication of what pin they are. or if the Num value is the pin number why are their multiple of the same number? ie 0 , 1 , 0 , 2?

Its a little awkward, You have to look at the 7I47 pinout (in the 7I47 manual)
and the SVST2_4_7I47.PIN file at the same time:

It looks to me like
STEP0 TX4
DIR0 TX5
STEP1 TX6
DIR1 TX7
STEP2 TX8
DIR2 TX9
STEP3 TX10
DIR3 TX11

PWM0 TX0
PWMDIR0 TX1
PWM1 TX2
PWMDIR1 TX3

ENC0A RX0
ENC0B RX1
ENC0Z RX2

ENC1A RX3
ENC1B RX4
ENC1Z RX5

ENC2A RX6
ENC2B RX7
ENC2Z RX8

ENC3A RX9
ENC3B RX10
ENC3Z RX11

Ok, thats making some sense, so IO# 0 is tx4 and /tx4 (the first two pins), IO# 1 is tx5 and /tx5 (the 4th and 5th pin) and so on. Then the Num in the pncconf - I/O connector 2 tab - is the Chan.

Is the X Encoder my direction control?

direction control?

If you are using EMC 2.5, the PIN file print out should be found in the pncconf help page's output tab when on the Mesa page.

What version of Linuxcnc are you using?

I am using 2.5 from buildbot.

For direction control I mean on the gecko 203v's I have 4 control inputs, disable, dir, step, and common.
The manual for the 203v says "TERMINAL 8 Direction Connect the DIRECTION line to this terminal."

But I do not see anything in the mesa manuals to indicate what that would be, so I was guessing it may be x encoder?