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This cable works with the serial port pinouts on all Asus motherboards. No modification of header connector needed. Simply plug the connector onto the 2x5 pin-outs in such that line 1 (red) is connected to pin 1. For othet motherboards, please check the manual for pin assignments, and follow the connection guides on this page.


serial internal


FRONTX Serial 9 Pin Internal


One small bay

Serial d-sub 9 pin male
2x5 header connector female

Flat cable (UL 2651)
Length - 2.5 feet (762 mm)


wire assignments

Line 1: CD - carrier detect
Line 2: RXD - receive data
Line 3: TXD - transmit data
Line 4: DTR - data terminal ready
Line 5: GND - system ground
Line 6: DSR - data set ready
Line 7: RTS - request to send
Line 8: CTS - clear to send
Line 9: RI - ring indicator

Note - line 1 of ribbon cable is marked red.


Most motherboards provide 2 internal serial ports, commonly named as COM1 and COM2, which means you can connect up to 2 FRONTX serial ports.

connection guides

Diagram 1: Each serial port header (COM 1 or COM 2) usually consists of 10 pins arranged in 2 parallel rows, i.e. 5 pins on each row. The pin no. 10 is a "dummy" pin (no connection required).

Diagram 2: Common pin assignments of serial port header are shown in the diagram above.

Diagram 3: Simply plug the connector onto the header, and please take note of the orientation of line 1 in relation to the header's layout, i.e. line 1 must be connected to CD pin.... line 3 to TXD pin, etc.

If the pin assignments of your serial port header are different from the example shown above, no problem, simply rearrange the wires within the header connector so that all wires are correctly connected to the appropriate pins (i.e. wire assignments and pin assignments are matched).


For some old motherboards, the pin assigments are not shown in the manual. It simply indicates pin 1 only. This is because the serial port cable was bundled with the motherboard. So, the manufacturer assumed that you do not need to know the pin assignments.

If that's the case, one easy way to check; is to open up the serial port cable that was bundled with your motherboard, and see how the wires are soldered.

cable connection 1

If line 2 is connected to 2nd pin, line 3 to 3rd pin as shown in diagram a, then the pin assignments of your serial port header is similar to the example shown in diagram 2 above.

cable connection 2

If line 3 is connected to 2nd pin, line 5 to 3rd pin as shown in diagram b, then the pin assignments of your serial port header is shown in diagram c below.

pin assignments

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