Unfortunately, there is only one 9 pin serial port on the back of the 500.  I have always used this for NEMA outputs to my agleader YM2000, but now my RTK antenna is using the spot.  I tried putting a serial splitter in the port, but when I hook up the yield monitor and the RTK, I lose the signal on both.  There has to be a way to go in to a EZ-500 with RTK and output the signal to a Yield monitor, but I can't figure it out.

TIA 

Lanky