I have a drawer full of USB/RS232 adapters... is it possible to attach the Tx/Rx pins on the serial end of this cable to the Tx/Rx GPIO pins on the pi and have console access?
EDIT: Bought this: http://www.amazon.com/gp/product/B00FEAMUOK/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1
No. The Raspberry Pi Tx/Rx GPIO pins are 3.3 volt logic. Standard RS-232 serial can be as high as 12-15 Volts. Connecting a standard RS-232 directly to the GPIO will probably damage the Raspberry Pi.
So you have some computer running a terminal emulator, but that computer only has a USB serial port. You want to plug your converter cable into that USB port and connect the RX, TX and GND pins at the D-shell connector to the corresponding GPIO pin on your PI. ... and the answer is ...maybe. https://elinux.org/RPi_Serial_Connection
Check the voltages at the D-shell. These old converter cables typically output a 5 volt TTL signal at the D-shell. The signals at the D-shell connector are derived from the USB 5 volt power. These serial converters generally do not boost the voltage, but 5 volts is still enough to damage a PI's GPIO. You will need some kind of simple level shifter to interface the converter's 5V logic to the Pi's 3.3 V logic. https://elinux.org/RPi_GPIO_Interface_Circuits#Level_Shifters
If you build a level shifter, your idea can safely work. Of course, there is also the lazy man's method. https://www.adafruit.com/product/954
type lsusb on your terminal you should see the device. Go to this link for details on how to use it.
http://elinux.org/RPi_Serial_Connection#Console_serial_parameters
you may need to install "screen" on the pi.
You could use this to connect RX/TX from GPIO header to USB. http://www.ftdichip.com/Products/Cables/RPi.htm
It does not need any additional drivers, since support for the ftdi chips is already integrated into the kernel.
You may have to install some packages though to access the serialport, depending on your distro. Screen, minicom, microcom should all work.
