6 pin MMJ female connector at the devices.
6 pin MMJ male connector at the cables.
|1||DTR||Data Terminal Ready|
|2||TXD+||Transmit Data +|
|3||TXD-||Transmit Data -|
|4||RXD-||Receive Data -|
|5||RXD+||Receive Data +|
|6||DSR||Data Set Ready|
A common task is to build an adaptor to RS-232 using the DB-25 or DE-9 plug on the one side (to be connected to a PC) and the MMJ connector on the other. Though serial transmission is done with differential voltage, it’s actually quite easy. Simply connect MMJ pins 3 and 4 to the DB-25 / DE-9 GND pin, then use MMJ pins 2 and 5 as regular TX/RX pins (to be connected to pins 2 and 3 on the DB-25 / DE-9 side, depending on whether to build a direct crossed console cable or just an adaptor. You can also connect pins 1 and 6, but I’m not exactly sure where. For a plain console cable, they are not necessarily needed.