I am developing a product which is to drive a Sony or similar VTR.
I have the DB9 connector pinouts1 GND 2 RXA 3 TXB 4 GND 5 GND 6 GND 7 RXB 8 TXA 9 GND
and it's working OK.
However, for an unrelated purpose I need to know whether the RS422 product being controlled actually connects to *all* the pins marked GND.
I believe the straight-through DB9-DB9 cable normally used in these applications does have all nine pins connected through, but is it normal for the device itself to have GND on all of them?