VXC-114U/144U/144iU User’s Manual (Ver. 1.2, Mar.11, 2009) -----16
2.3.4. VXC-144U/VXC-144iU 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!