Required Parts and Tools
Wire Crimpers (Optional)
1 - RJ-45 connector (Optional)
9-Pin Serial Cable
4-Wire Splice Connectors
Step 1: Strip the Serial Cable
2) Using the strippers, remove roughly 2 inches of the cable covering on the cut end to expose the inner wires.
Step 2: Map the 9 Pin Holes to Inner Cables Using Multimeter
2) Insert either multimeter rod (red or black) into first pin hole of serial cable.
3) Make contact with inner wires (inside inner shield) with other rod one at a time.
4) When the multimeter picks up a reading, then the pin hole being used is connected to the wire being touched.
5) Repeat steps 2-4 until all inner wires are mapped to their pin holes.
Step 3: Remove Unnecessary Inner Wires
c) Ground (there may be multiple, pick only one)
2) Set aside the inner wires corresponding to the designated pins along with the bare wire (also ground).
3) Cut off the unnecessary inner wires.
Step 4: Strip the Ethernet cable
2) Remove roughly 2 inches of the cable covering on the cut end using the wire strippers to expose the inner wires (there should be 4 twisted pairs).
Step 5: Determine Designated Inner Wires for Ethernet Cable
2) Determine which inner wires are connected to pins 3, 6, 7 and 8 counting from left to right (usually green and brown pair).
3) (Optional) Use RJ-45 end and wire crimpers to recrimp the Ethernet cable if it's not standardized.
Step 6: Remove Unnecessary Inner Wires from Ethernet
2) Cut off the other wires, along with the inner plastic piece, if there is one (on most new cables).
3) Untwist both pairs.
Step 7: Connect Inner Wires of Serial and Ethernet
Caution: Make sure to push wires as far back as they will go into the 4-pin wire splicers to ensure a proper signal flow and avoid malfunctioning cables.
2) Clamp down the used side of the 4-wire splice connector using the end of the wire strippers.
3) Repeat steps 1 and 2 for the inner wires corresponding to pins 7 and 8 of the Ethernet cable using the other 4-wire splice connectors.
4) Push the inner wire of the serial cable corresponding to the receive pin into the opposing slot of the 4-pin wire splicer containing the inner wire corresponding to pin 3 of the Ethernet cable.
5) Repeat step 4 for the remaining inner wires corresponding to the following pins:
a) Transmit pin of serial cable to pin 6 of Ethernet cable (clamp down completed side).
b) Ground pin of serial cable to pin 7 or Ethernet cable.
c) Bare inner wires of serial cable to pin 8 of Ethernet cable (clamp down completed side).
Step 8: Cover Connections Using Electrical Tape and Clean Up
2) Clean up the mess and put away the tools; it's time to test the new cable.
Congratulations! You now have a (hopefully working) 9-pin serial to Ethernet cable. If there is a problem, it usually has something to do with mapping designated pins with correct inner cables. First, try to re-crimp the 4-wire splice connectors to ensure a solid connection. Then go back and check your cable mappings. Think of all the other cables you can cross with an Ethernet cable!