MAC Address of Controllino

[tomas.kracmar]

Hi Controllino fans, where can I find MAC address of my Controllino?

Thank you for response.

[Lukas]

Hi Tomas,

WIZnet chipset W5100 has no fixed, or assigned MAC address, so the CONTROLLINO is sold without a MAC address.

Until the CONTROLLINO is not online and operated just in the LAN, it is not necessary to have a unique MAC address.

If you really need a unique MAC address for your CONTROLLINO, please contact us at info@controllino.com.

Thanks,

Lukas

[w-mets]

Hi Lukas,

I am facing some troubles in running DhcpAdressPrinter, I constantly get back “Ethernet shield was not found. Sorry, can’t run without hardware. :(“

Ethernet seems to be correctly connected in IPv4. As I reccon, I don’t have to fill in any MAC adress in the code, and I am using “Ethernet.init(10);”

Could you help me solve this?

Best regards,

Wouter Mets

[Flo]

It is the other way around if you put a device on the Internet (behind a router) the MAC address doesn’t matter. In a local switched network every device should have a unique MAC address.

I have accidentally assigned two PLCs the same MAC Address. It is very important to have an unique MAC Address. If you put the PLC online it doesn’t matter at all. MAC Addresses are for Layer 2 in the OSI Model. The Layer 2 only matters for switches in you local Network. A router takes the Ethernet frame takes out the packet (that is inside one or multiple frames) and puts in a new Ethernet Frame (with its own MAC as a source address in the frame) This Networking stuff is like an onion. Sometimes a router can even split a packet in multiple frames. Home routers also modify the IP addresses before sending it out to the internet. But usually routers in the Internet and you local network don’t touch the IPs from packets. Only when you use non unique IPs (like private ones in the IPv4 world) you have to mess with the IP Header of a packet before sending it out to the internet. In the IPv6 world you don’t need that anymore at all.

Switching is a technique to reduce the traffic on each network cable back in the day (before switches where so cheap) every computer got all the Ethernet frames (which results in a slower network with more and more devices). Now days a switch reads the MAC from the the ethernet frame. it has a list of mac addresses on which port is which mac connected and sends out the frame only on that specific physical port (connector). That list is called ARP Table. If you want to intercept the traffic of others in the network you have to attack the switch first. ARP Spoofing, or flooding the switches table memory for example. If you have multiple devices with the same MAC the switch behaves weird. Maybe it sends out the frame to both links or just one. In my case the PLC had to communicate with each other which didn’t work. The switch sent the frame only out one link.

<div>Also important is that when you connect two switches don’t build loops without any link aggregation protocol and/or STP (Spanning Tree Protocol). It can happen that a frame is send round and round between switches. Especially if you have a redundant and robust network with mutiple connections between switches.
</div>

x2:xx:xx:xx:xx:xx
x6:xx:xx:xx:xx:xx
xA:xx:xx:xx:xx:xx
xE:xx:xx:xx:xx:xx

Are reserved and not used by any vendor. Like public and private IPs there are reserved ranges of MAC addresses. These can be used in virtual machines or linux containers or custom stuff you build, like PLCs, electronic devices …

[Bri-Guy]

Lukas,

I am ALSO having the identical problem that w-mets has described above ==> I run the DHCPAddressPrinter verbatim as you described in the Tutorial and I get the same replay w-mets did: “Ethernet shield was not found. Sorry can’t run without hardware.”

However, I did NOT uncomment ANY of the “Ethernet.init(?)” lines at all.

respectfully,

Bri-Guy

[Bri-Guy]

Never mind Lukas I think I figured it out.

The DhcpAddressPrinter sketch requires that the Controllino have an physical ethernet cable connection to a router or a device that has a DHCP server that can SUPPLY an IP address to the Controllino and then you can see what address is assigned by the router to the Controllino in the Serial Monitor.

I hope this helps you w-mat in figuring out why the program was giving you that message.

Bri-Guy