VXC-112(i)(A)U/142(i)AU/182i(A)U/114(iA)U/144(i)U, VEX-114(i)/144(i) , VEX-112(i)/142(i) User’s Manual (Ver. 1.5
Aug.10 2012) -----18
2.3.4. VXC-144(i)U/VEX-144(i) Pin Assignment
DB-37 to 4-port DB-9 (CA-9-3715D)
Warning:
The RS-485 bus is a differential (balanced)
signal, thus
you cannot wire the Data+ with
Data- directly for a single port loop-back
test.
It will not work at all!