I have an Ethernet device that works with Microchip's ENC28J60 chip perfectly. So if I want to connect a cable from a switch/controller, to device 1 (that has 2 RJ45 jacks), then have device 1 second port connect to device 2 1st port, then device 2 2nd port to device 3 1st port so communications will be communicated to all 3 devices.

Kind of like a RSTP network with daisy changed devices with their own separate IP addresses.

I found this thread for a 3 port passive HUB.

Also another reason is to not have to run cable from each device back to a central switch in a large warehouse or building. Each device can plug into the next device closest to it and so forth.

Basic diagram:

enter image description here

So if use just ENC28J60 chip... I would need to figure out how to preform the connections from ENC28J60 to a Micrel un-managed mode chip, so not having to add another MCU chip with more overhead.

I found this Application note from Microchip: For using • Configuration Straps for basic/auto configuration without MCU

I also searched here more and found the right topology - simple topology based on link aggregation, up to 200 Mbps of overall system performance is hypothetically reachable High speed data from microcontrollers to pc using daisy chain

  • \$\begingroup\$ buy a cheap 4 port ethernet switch \$\endgroup\$
    – jsotola
    Oct 28, 2020 at 22:26
  • \$\begingroup\$ Thanks, but needs to be embedded into device, and not reasonable to have inexpensive 4 port switches all through out a large building that could consist of 25 devices or so. \$\endgroup\$
    – blackedpi
    Oct 28, 2020 at 22:29
  • 1
    \$\begingroup\$ please draw a network topology diagram of your LAN \$\endgroup\$
    – jsotola
    Oct 28, 2020 at 22:31
  • 1
    \$\begingroup\$ Ethernet is not a bus, so a single segment can only contain two endpoints. Passive passthrough so more than 2 devices communicate over Ethernet using twisted pair is not possible. \$\endgroup\$
    – Justme
    Oct 28, 2020 at 22:41
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    \$\begingroup\$ The funny thing is that old-style Ethernet, pre-twisted pair, used a coax cable as a bus and devices could be add or removed from the bus at will, without disrupting other devices. Unfortunately, this technology is completely obsolete, as well as very speed limited. \$\endgroup\$
    – DoxyLover
    Oct 29, 2020 at 8:31

1 Answer 1


Splitting twisted-pair Ethernet passively cannot be done. Each Ethernet link is a point-to-point connection, where only two devices, one at each end of the cable, can communicate with each other.

  • \$\begingroup\$ Yes it can be. Passive diode hubs still work. \$\endgroup\$
    – Passerby
    Oct 29, 2020 at 21:30
  • \$\begingroup\$ @Passerby I seriously think that passive diode hubs won't work. If so, then please show evidence how it could possibly work, has it ever worked? How the TX and RX lines would be connected? How the devices would even negotiate the link up and running? Wouldn't the signal amplitude suffer from multiple terminations? Wouldn't the signal suffer from stubs and reflections? There is nothing like that in the Ethernet specs. \$\endgroup\$
    – Justme
    Oct 29, 2020 at 21:42

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