I have successfully set up a link to my guruplug from a macbook pro using a USB-Serial adaptor, with a 3.3V setting.
I have GND--GND, TX--RX, RX--TX connected. I have double checked the connections for continuity as far as I can i.e. that my micro connector has continuity with where the cable plugs into the header of the adaptor (it is an exposed PCB type).
On booting the plug, the boot sequence is received into the terminal program all OK.
I cannot however transmit anything to the plug; it does not receive anything when keys are pressed to interrupt the boot. Once booted, and the message that the network adaptor has started, the login prompt is not appearing.
Am i missing something obvious, or is my serial comms broken somehow? I have heard a lot of these serial cables are counterfeit?