I recently got caught out by not having a functioning Null Modem cable with Hardware Flow Control pins connected. A bit of a niche one, but I did have several hundred HP switch console cables. I did a bit of reverse engineering thanks to Google, and managed to get a pinout. I used two HP console cables, snipping off the RJ45 plug, and connecting the wires. The pins in the RJ45 connector correspond to the COM/RS232 connector at the other end thus:
|RJ45 Pin||Cable Colour||COM Pin|
You’ll need to connect the cables in the following manner to build the cable:
RJ45 Pins 2-3 need to be connected (Red+Green)
RJ45 Pins 4-6 need to be connected (Blue+Brown)
RJ45 Pins 5 need to be connected to eachother (i.e. Orange+Orange)
RJ45 Pins 8-7 need to be connected (Purple+Black).
Of course, there will be two of each colour – ensure they all follow the above.
You should now have a working Null Modem cable with Hardware Flow Control pins connected.