no network, meaning no dhcp server to give an address i hope, use fixed ip address on each, with network hub ok, no hub then you need a network cable with crossed wires. or each rpi might have a 169.254.x.x. address, so no need for a fixed ip address, already auto configured, and/or see raspi-config
192.168.x.x with network mask 255.255.255.0 (24 bit) is not needed, 255.255.0.0 also works (16 bit), router/hub does not care if your range is different from other devices, it just isolates the rpi from internet probably.
![Serial Communication between Raspberry Pi and Arduino [1H Complete Tutorial]](http://i.ytimg.com/vi/jU_b8WBTUew/mqdefault.jpg)
does this work if both Pi’s are offline? I need to send pings over an Ethernet cable to each other with no network
no network, meaning no dhcp server to give an address i hope, use fixed ip address on each, with network hub ok, no hub then you need a network cable with crossed wires.
or each rpi might have a 169.254.x.x. address, so no need for a fixed ip address, already auto configured, and/or see raspi-config
192.168.x.x with network mask 255.255.255.0 (24 bit) is not needed, 255.255.0.0 also works (16 bit), router/hub does not care if your range is different from other devices,
it just isolates the rpi from internet probably.
Good video o/