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Thanks! I think i will dive into the deep and order a 7i76EU. I don't need that much I/O now, but not sure in the future. I like to play with the idea of having more axis and sensors like endstops to the machine. Also i have coolant pump and airlines for blowing chips away. Its manually controlled at this moment, but automating this is on my list . One last question:

eusurplus.com/index.php?route=product/product&product_id=50

Is referring to a 'daughter' card. Would that imply that i need something extra?

Is this a plasma?

Thank you, that makes it more clear. I will measure all the cabling and ground connections.

I wouldn’t mind rewiring everything — my setup is quite simple, and the CNC machine is fairly small. For me, building and tweaking the CNC is part of the fun of the hobby.

I’ve read that many of you use various Mesa cards. I was hoping the 7i76EU alone would be a good starting point to learn how to work with Mesa hardware. Do you know if that’s the case? I saw some brutal shipment costs (like 200 dollar plus, so i will have to search for an European supplier, i'm in the Netherlands)

If the 7i76EU would allow me to completely move away from the parallel port, that would be a big plus — especially since I’m currently limited by base-thread latency.

[EDIT]

I see a seller with reasonable shipping costs, not sure if its a trusted compane EUSurplus?I think i am planning to switch to a Mesa board and wanted to check if the 7i76EU is the right fit for my setup. This is what I’m working with:

• 3x DM542A stepper drivers (they use step/dir signals)
• 3x LJ12A3-4-Z/BY inductive proximity sensors (used for homing)
• 1x Huanyang VFD (spindle, controllable via 0–10V or RS-485 Modbus (I think because i now use it over USB)

From what I’ve researched, the Mesa 7i76EU seems like the best option. Here’s why:

• It supports up to 5 stepper/servo axes via step/dir signals (perfect for my DM542A drivers)
• It has 32 opto-isolated inputs which should work well with the 24V NPN homing sensors
• It has 16 outputs, which are configurable (sourcing/sinking)
• It includes an analog spindle output (0–10V) for VFD speed control
• It supports RS-485 communication if I decide to use Modbus for the Huanyang VFD
• It isolates field I/O power from logic power, which helps protect the system

Important to note:

• The sensors might need a pull-down resistor to give clean logic signals when connected to 24V. I already solderd a pc to convert the 30V signal back to a 5V system with opto's
• I will need to supply 24V field power to the board 
• I understand the 7i76EU requires a second Ethernet interface on my PC (either a second NIC or a USB↔Ethernet adapter)
• I still need a PREEMPT-RT kernel, but I won't have to worry about tight base-thread latency anymore

Does this sound correct to those of you with experience using this board?Thanks in advance!

 

You would need a stiffer pullup so you get more than 12V at the 7I76E input

I would suggest 2.2K 1/2W

You could also use two separate inputs and an OR or MUX component
(the MUX component has the advantage of ignoring the other input
when not in use, but requires a signal to select which input shouls be active)

Hello again!
My next problem to get my machine running (it's running but not as precise as I want it) has to do with two switches.
My tool length sensor is a quite normal mechanical switch, that is NC and put +24V into input-08-not. That's working perfectly.
If I put my 3d Sensor (NPN-NO) into the line as the picture shows, nothing works. The 10k resistor (R1) before the Tool length switch puts the voltage down to 12.xVolts, the Input-08-not is set to "probing" permanently.
The 3D Sensor does nothing at all, not even the LEDs are active (the output is an open collector, I presume). What about diodes?
 

So, my next thought is to disconnect the two sensors from each other and use another Input of my MEsa 7i76e just for the 3D Sensor. This input should not be inverted for correct funktion. How can I do this with or without using an OR2 funktion?
My lines for the tool length are as follows

#---PROBE-IN ---
net probe-in     <=  hm2_7i76e.0.7i76.0.0.input-08-not    
net probe-in     =>  motion.probe-input

AFAIK, I cannot just net another input to motion.probe-input. But how could a OR2 look like?

Thanks for your help, again!
Hanno
 

If Step/Dir resistor networks or driver chips are being damaged
it means a voltage considerably outside the 0 to 5V range is being
applied to the Step/Dir pins.

First thing I would check is drive grounding and Step/Dir wiring
Routing step/dir lines parallel to servo motor wiring might also
cause enough EMI to damage the drivers.

An intermittent short to 24V wiring is another possibility.

A while ago, my MESA 7i76E broke; one channel just stopped working. I wrote about that here . I then found someone who repaired the card, after which the machine ran fine for half a year. He said he "replaced the resistor network" of the channel.

Today, the exact same issue appeared again. Joint 2 stopped working and after a restart it worked for a minute and went away again. This is exactly the behavior I saw last time.

This time though I was better prepared and had a spare 7i76E ready to replace the other one. After replacing it the machine ran fine - but after an hour the new card displays the same behavior, too! Clearly something is going on that breaks this channel... sometimes.

What would you do to diagnose this? Replace the JMC servo (with the built in controller) and hope for the best?

Hi Todd,

Thanks for your response — I’ll definitely give that a try, as it feels like my last resort with this current setup.

I've already disabled everything I possibly could in the BIOS. The only things I haven't touched yet are the memory timings and voltages. If this doesn’t work either, I’m honestly not sure what else is left to tweak.

I'm also considering switching to a Mesa card, possibly the 7i76EU, but I have zero experience with Mesa hardware. I’ll need to figure out whether it will work with my three DM542A stepper drivers, and also with my VFD, which is currently controlled over USB using: `loadusr -Wn vfd hy_vfd -n vfd -d /dev/ttyUSB0 -p none -r 9600`

Things i disabled next to the obvious, like settings for fixed clock speeds (fclock 1066, bclock 1000) disabling power management and disabling hardware that is not being used (BT, Wireless, serial, audio, fancontrol (disabled fixed on 100%)):

BIOS Settings (set to Disabled):

SMT / Hyperthreading
→ Disables logical cores to reduce cache sharing and latency spikes

C1E, C6, and other C-States
→ Prevents the CPU from entering sleep states, ensuring consistent timing

Streaming Stores Control
→ Avoids aggressive memory write optimizations that can disrupt real-time behavior

DRAM Scrub Time
→ Turns off background memory error checking to avoid unexpected memory bus usage

GMI Encryption Control
→ Disables inter-chiplet encryption on Infinity Fabric to reduce overhead and latency

XGMI TXEQ Mode
→ Prevents signal equalization tuning that could introduce instability or variability

DRAM Map Intervention
→ Disables memory remapping logic that can introduce unpredictable latency

DF Sync Flood Propagation
→ Prevents error broadcasts across chiplets, reducing the chance of system-wide stalls

Good day,
Adding a voice here as I think I saw another user having this issue: RPI5 with a 7i96, and after some time I get a solid red INIT light on the mesa card, and obviously at that point have to reset the card to continue. I cant make heads or tails of this just yet, but it might be related to idle. It may be specific to the 7i96 given the other poster also commented on that. I have 7i76EU on its way so will be able to test this and post back whether I experience anything similar. Currently the Mesa is on a 5v3A wall plug, and the RPI5 uses a somewhat official USBC RPI wall plug.

Working like a charm.
Thank you very much Peter!

P.S.
Damn self-made DB25 cables. Firmware initially didn't make any difference. Apparently cables on P1 and P2 were backward. Reversed both DB25 connectors and now I see both 7I76 and 7I89 and encoders are working. These Mesa cards seem to be very robust, even all wrong signals on all the wrong pins didn't make them go dead.

7I76EU firmware with 7I76 on P1 and 7I89 on P2

 

Each connector is independent, though module channels may differ between firmwares
Note on the 7I89, you may need to turn on Encoder power (depending on jumpering) and it
also requires  both cable  _and_ external 5V supply to P1.

PCW wrote:

Wrong firmware, 7i76eu_7i76x1_7i88_7i89d.bin is for a 7I76EU +7I88 (P1) + 7I89 (P2)

I'll take a look at making a config for a 7I76 (P1) and 7I89 (P2), but probably tommorow...
 

Would it be 7I76U (with sink/source I/O option and spindle/encoder interface) on P1 and 7I89 on P2?
Also, 7i76eu_7i76x1_7i88_7i89d.bin has 7I89 on P2. Should 7I89 on P2 work even if 7I76 on P1 doesn't? Or P1 and P2 handling is interdependent?

Wrong firmware, 7i76eu_7i76x1_7i88_7i89d.bin is for a 7I76EU +7I88 (P1) + 7I89 (P2)

I'll take a look at making a config for a 7I76 (P1) and 7I89 (P2), but probably tommorow...
 

That may be, but I have 7I76U and its manual says (www.mesanet.com/pdf/parallel/7i76uman.pdf page 5) that sserial should be on DB25 pins 7-10 (two of them in fact), while 7i76eu_7i76x1_7i88_7i89d.pin file has just one sserial on pins 11-13 and no spindle encoder. It instead has 2 additional stepgens which my 7I76U doesn't have.