Chibi Consulting
References to 422 adapter cards

RS-422 and RS-485 computer adapters / Converters

When selecting a computer interface to a broadcast device, the key is that some of the 422/485 adapters do not have SMPTE 9-pin wiring and you may need to make an adapter so that the cables you use are standard straight through pinouts. Your adapters should always reside directly on the 422/485 connection from your device so that all wiring in your facility will be SMPTE standard. This consistency will pay off when troubleshooting later as devices are swapped around.

Below are a few of the companies that supply adapters for use in the broadcast industry. This list is not complete and I am not making any recommendations as to your choice of vendors, this document is only to provide you with the information you might need to make your choices. Let me know if you find others that should be linked. contact 23 at chibiconsulting dot com

SMPTE compatible pinouts

Non-SMPTE pinouts; however, adapter available

Native Pinout (Not SMPTE)
TX+Transmit Data Positive4Output
TX-Transmit Data Negative3Output
RX+Receive Data Positive1Input
RX-Receive Data Negative2Input
5V/12VPower selected by E19Output

Non-SMPTE pinouts

Pinouts (Non SMPTE)
RD(A)-Receive Data AInput1
TD(B)+Transmit Data BOutput2
TD(A)-Transmit Data AOutput3
GNDSignal Ground------5
RD(B)+Receive Data BInput9

Undetermined pinouts

Appendix A SMPTE 207m summary

SMPTE 207m Interconnection summary
SMPTE 207m 422 master on db9
1Frame Ground
2Receive 'A' -
3Transmit 'B' +
4Transmit common Ground
6Receive common Ground
7Receive 'B' +
8Transmit 'A' -
9Frame Ground
SMPTE 207m 422 tributary on db9
1Frame Ground
2Transmit 'A' -
3Receive 'B' +
4Transmit common Ground
6Receive common Ground
7Transmit 'B' +
8Receive 'A' -
9Frame Ground