VLANs or multiple ethernet cards?
- nanowhat
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16 Sep 2025 19:48 #335084
by nanowhat
VLANs or multiple ethernet cards? was created by nanowhat
I'm planning a robot retrofit, which will use Ethercat servo drives, a mesa 7i94T (serving a 7i84U and 2x 7i73 boards), and an ethernet link to an existing Fanuc 31i-B5.
Is it practical to use 3 VLANs and a managed switch to connect these sets of devices to a computer with one physical ethernet port, or should I add extra ethernet cards? I want to use COTS gear wherever possible.
- I've read that ethercat can be run through a switch without difficulty, but I couldn't find anything regarding its behavior through a VLAN.
- I can't find any information on what one can actually do with mesa's ethernet links. I plan to connect some limit switches, discrete interfacing with the Fanuc 31i-B5, the user interface system, and some analog measurement through the mesa board set. Thus, it seems that real-time performance isn't critical.
- The link to the Fanuc 31i-B5 is ordinary switchable/routable ethernet with no special requirements. I plan to check the 31i-B5's operating mode and the state of certain R and X registers via FOCAS, but if that is delayed for a few hundred milliseconds I don't anticipate trouble.
Is it practical to use 3 VLANs and a managed switch to connect these sets of devices to a computer with one physical ethernet port, or should I add extra ethernet cards? I want to use COTS gear wherever possible.
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- JacobRush
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16 Sep 2025 20:56 #335087
by JacobRush
Replied by JacobRush on topic VLANs or multiple ethernet cards?
I have not actually tested it but I would think it would work just fine doing tagged on the PC ethernet port with subinterfaces (or however linux does it these days its been a minute) and exposing those segments as untagged to the devices. I don't think there is a way for the devices to even know its a vlan somewhere when hanging on an untagged port.
You'll need not-overlapping subnets on the vlans if you need IP connectivity over and above just ethernet frames.
You'll need not-overlapping subnets on the vlans if you need IP connectivity over and above just ethernet frames.
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- nanowhat
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16 Sep 2025 21:07 #335088
by nanowhat
If I were to run LinuxCNC on a raspberry pi (whatever variant), I could potentially handle the UI (buttons, maybe some LEDs, the MPG) through the GPIO pins, and move the digital/analog I/O to ethercat devices, which would completely eliminate the Mesa hardware. That would still require ethercat on one VLAN and general purpose ethernet on another.
I might try it each way and see what works.
Replied by nanowhat on topic VLANs or multiple ethernet cards?
That's what I figured.tagged on the PC ethernet port with subinterfaces (or however linux does it these days its been a minute) and exposing those segments as untagged to the devices.
If I were to run LinuxCNC on a raspberry pi (whatever variant), I could potentially handle the UI (buttons, maybe some LEDs, the MPG) through the GPIO pins, and move the digital/analog I/O to ethercat devices, which would completely eliminate the Mesa hardware. That would still require ethercat on one VLAN and general purpose ethernet on another.
I might try it each way and see what works.
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- unknown
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16 Sep 2025 22:32 #335092
by unknown
Replied by unknown on topic VLANs or multiple ethernet cards?
As long as network latency isn't impacted theoretically it may work.
The RPi will suffer somewhat if you require the use of a base thread for some input requirement. Personally I think an SPI for simplicity a 7c81, which is simple to replicate using off the shelf Spartan 6 Dev boards, maybe a better option for IO.
The RPi will suffer somewhat if you require the use of a base thread for some input requirement. Personally I think an SPI for simplicity a 7c81, which is simple to replicate using off the shelf Spartan 6 Dev boards, maybe a better option for IO.
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- unknown
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16 Sep 2025 22:37 #335093
by unknown
Replied by unknown on topic VLANs or multiple ethernet cards?
The mesa website has a manual for each and every board, so that should give you enough with what you can do with mesa ethernet, a base card is very easily extended via smart serial cards. The access at register level is documented in each manual.
While obtaining mesa hardware outside of the US due to postage, it can almost double the price for items coming Down Under they are solid and reliable and very well supported
While obtaining mesa hardware outside of the US due to postage, it can almost double the price for items coming Down Under they are solid and reliable and very well supported
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- Hakan
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17 Sep 2025 02:07 #335102
by Hakan
Replied by Hakan on topic VLANs or multiple ethernet cards?
I wasn't able to make the ethercat master use the vlan interface, only the physical.
On the other hand I don't really know what I am doing, so a test is advised.
On the other hand I don't really know what I am doing, so a test is advised.
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- nanowhat
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17 Sep 2025 02:53 #335103
by nanowhat
Replied by nanowhat on topic VLANs or multiple ethernet cards?
That's not my concern. I remember hearing somewhere that the Mesa ethernet link takes over the whole interface, and prevents other traffic from using it too. Wherever I heard that, nothing was said about VLANs, so I assume they were using the physical interface. If the mesa link wants to take over the VLAN that's fine, but if it takes the whole physical interface in spite of VLANs being configured, that would be irritating.that should give you enough with what you can do with mesa ethernet
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- tommylight
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17 Sep 2025 03:20 #335107
by tommylight
Replied by tommylight on topic VLANs or multiple ethernet cards?
Multiple Ethernet cards.
And Mesa always wired directly to the PC, not through HUB or Switch or VLAN.
Now that is out of the way, i have tested Mesa cards through cheap switches (non manageable) and it worked for me without issues for weeks at a time, but i would never run a production machine through it.
I do not know if EtherCAT works through any of those as i never tested this. But i have seen something used for EtherCAT redundancy several years back at a machine show, for some strange reason i did not pay attention.
And Mesa always wired directly to the PC, not through HUB or Switch or VLAN.
Now that is out of the way, i have tested Mesa cards through cheap switches (non manageable) and it worked for me without issues for weeks at a time, but i would never run a production machine through it.
I do not know if EtherCAT works through any of those as i never tested this. But i have seen something used for EtherCAT redundancy several years back at a machine show, for some strange reason i did not pay attention.
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