Campbell Scientific NL100 Network Link Interface - Manual (Page 37)

Appendix D. RS-485 Connector, 3-Pin
Terminal Block
The RS-485 port is for connecting an MD485 multidrop interface to the
NL100. The MD485 attaches to the NL100 via a twisted pair cable such as the
#9720. The following table shows the pin-out information for the RS-485 port.
PIN I/O FUNCTION
1 GND Signal Ground
2 I/O 485_IO- (A)
3 I/O 485_IO+ (B)
I = Signal Into the NL100, O = Signal Out of the NL100
D-1