Gecko G320X - Closed Loop - Mesa 7i76E + 7i85

I am currently running a Porter/Powermatic 3 axis bed mill on Gecko 320X's with a Pico USC+Gecko Drive Interface.

My question is about my new project. I have a Millennium 4200 that I have installed 320X's but this time I'm stepping away from the parport and went with a Mesa 7i76E. Like the Pico setup I want to close the loop at the controller. I am running differential encoders to a 7i85. Do I simply jump the +A and +B for each axis from the 7i85 to the Gecko 320X? is there a "proper" way to appease the requirements of the drive without degrading the signal at the controller?

Thank You

Hi
why dident you go for 7i92 and a 7i77 in first place to get a real servo system the gecko suport this setup

dont forget the GND to be bridged to the controller THIS woudtent be nessesary at the 7i77 and EMI is off the system

DID you ask here about the items to use or simply get some infos around

bbsr_5a wrote: why dident you go for 7i92 and a 7i77 in first place to get a real servo system the gecko suport this setup

Gecko 320x are step/dir drives, so will not work with 7i77.

hoffb77 wrote: I am running differential encoders to a 7i85. Do I simply jump the +A and +B for each axis from the 7i85 to the Gecko 320X? is there a "proper" way to appease the requirements of the drive without degrading the signal at the controller?

The best solution would be to wire A+ and B+ to the 7i85, A- and B- to the Gecko, set the 7i85 for single ended encoders.
Jumping the same encoder output to two inputs usually works, but might be to much for some encoders, so the risk of missing the counts is present.

the amptzru port accept +-10V if you setup the drives to VEL mode

I will split them off like that and report my findings.

I have the encoders already ran to the 7i85. I will set the jumpers to ttl. Would there be an issue using the - terminal to jump the signal to the gecko from there?

Leave it as is, jump the wires to the gecko, do NOT jump the +5V, just gnd and AB.
Check if gecko AND Linuxcnc can count properly, if they do, leave it at that, if they do not, then some splitting is in order.
In the latter case, the answer to your question would be: YES.

In general I would have reservations about doing this, that is, connecting to a drives
encoder that was intended for local feedback only. One reason is that I think its likely
that the Gecko encoder ground is the same as the motor power ground, so will have
a lot of common mode noise. This coupled with the fact that the encoder signals
are single ended (TTL levels) is like to compromise the controller and drive signal
integrity

You are correct. On my other setup I can pull +5 on a DVM using the drive power ground and probing the enc+ and the common +5 on the Pico.

Do you have any insight on encoder signal conditioners? Automation Direct sells an affordable one. There are several top end manufacturers making them at top end prices. Allen Bradley makes one at $100 per output, unfortunately it has 8 outputs. :dry: BB-845

I'd go with different drives and I may down the road but the G320X and the Machdrives seem to be the only ready available and affordable drives with 20 amp capacity. They both require feedback to the drive. My current setup runs well. The Gecko's push big iron around without overheating for hours on end. I am upgrading to the Mesa setup to add more functionality and reliability. My major concern is the encoder signal integrity to the 7i85.

Automation Direct modules

I plan to purchase 3 of the FC-ISO-D modules. Would there be any benefit using the -C mod(open collector)?