Wiring a db9 conn to G540

I'm using 4 wire with a ground wire what pin does this fit. Best I can tell The bottom 4 pins are used for  a and b wires. but the grounding shield wire I'm not sure . what pin I found a old drawing of the G540 showing pin 5 a rev 4 manual shows 2,3,4 as ground. this is the connector end to the G540. I'm using terminal block for the motor splicing. I just need to know what pin the grounding shield wire go's on and which end the g540 end or the motor end. I believe the grounding should be only on the G540 end but what pin#

Thanks