7176E Inputs noise immunity and enable circuitry

HI,

Very interested in the MESA Combo Ethernet Comms/BreakOutBoard.

Wondering if the inputs of the 7176E are Opto Isolated and if that is a silver bullet against EMF/RMF.

Often I get random noise issues (on mach3 machines with cnc4pc bob (5v inputs)) and I am quite sure most of the time the problem arrives from the 2phase electricity from the building. I dunno.. is it a transformer on the street that creates electrical noise, or some factory on the vicinity, or solar powered inverters someone installed nearby?
The symptoms are generally the same..
-homing doesn't search properly and/or the bounce off the switch is very short.
-On usb controllers I used the comms is lost quite easily. Its a pain.

I could probably state that 1 out of 4 machine installs will have something like that happening.

I don't believe that my wiring is the problem. I try to follow the proper segregation while looming in the cables, install the vfd far from the 5volt lines, use line filters properly.. Most of the time I get not problems.. nice homming/bouce off and nice solid comms no dropouts. But on some buildings the noise issues are there and the control box/machine wiring is the same.

I read that the 7176E has Isolated inputs and that the Outputs can be wired with differential mode.

A couple of things cross my mind..
-What if I use 24v on the homing switches, will I have a clearer signal? (but I also read that the board takes 5-24v as inputs.. so if I have a 5v spike I have a trigger no?)
-What if the noise comes indeed from the 240v in? The line filter seems to fail.

On a second note, I would like to know if the 7176E has a way disable the outputs upon an estop. The bob I use at the moment has an enable pair of inputs(0 and 5V) which I use in the Estop circuit. The moment the 5v enable signal turns low, all my outputs are switched off. So, the machine comes to a controlled stop. If I switch the power off of the motor drives for an Estop, they momentarily move, specially Z axis.. drops due to its weight.

Big thanks

use the 24v to supply the homing and limits instead of grounding them , this should stop your problems
( the same supply as the vfield ) you may need to invert the input pins .
also use if it's really serious shielded cables on any low voltage carrying cables . home limits etc

the inputs are not opto isolated , however they are protected and run as a multiplexed fast serial over a seperate channel ,
so not quite the same as a basic bob .

mesa products are used in industrial applications and are built as such ,
you mention if the 7i76e has a way to disable outputs , this depends on what outputs you are talking about , the spindle outputs are independently controlled , the 7i76e can't disable any other outputs directly , however linuxcnc can and does .
mesa cards also have a watchdog integral to the communications back to linuxcnc .

stepper connections have an enable just the same as mach3 ,
you'll find the 7i76E is in a total different league to a basic breakout board ,
you wont have any of the problems you associate , due to the way everything works .

Thanks again for the reply @cncbasher.

Just recently I read the manual for the 7176E and I really like to read this paragraph in there... this makes things quite clear in regards to noise immunity/homing and inputs signals "robustness".

"FIELD INPUT CHARACTERISTICS
The 7I76E field inputs have a nominal input resistance of 10K Ohms to field power
ground. 7I76E inputs sense positive input voltages above a preset threshold. For best
general purpose use, default input threshold is 50% of the field power supply voltage with
10% hysteresis. That is with a 24V field voltage an input must be brought to 60% of 24V
= 14.4V to be sensed as high and then brought to 40% of 24V = 9.6V to be sensed as low.
These accurate thresholds and hysteresis allow high speed field signal detection while
maintaining excellent noise immunity."

Still a bit early for me to wire up my 7i76E but I've only got a couple of parts left to make to have a plasma Z axis!

This diagram shows a suggested method of wiring in Estop to a Mesa card
robotech.lt/wp-content/uploads/2015/04/7...mple_connections.pdf

I think ditching 5 volts and moving to 24 volts will go a long to solving noise problems.

A friend recently bought a Smooth Stepper for Mach 3 and I bought Mesa from Big John T. I can say there is no comparison to it and the 7i76E (which is twice the size of the Smooth Stepper.)