ETS-Lindgren HI-6100 Field Monitor - Manual (Page 49)

Remote Operation | 49
 Signifies output from the HI-6100
 Signifies input to the HI-6100
HI-6100
Pin #
Signal
Data
Direction
Description
1 DCD 
Device Carrier
Detect
2 RD  Receive Data
3 TD  Transmit Data
4 DTR 
Data Terminal
Ready
5 GND N/A Ground
6 NC N/A No Connection
7 RTS  Ready to Send
8 CTS  Clear to Send
9 NC N/A No Connection
Figure 35: HI-6100 Pin # Designations Table
A null modem cable or adapter (supplied by the user) is required for
interfacing the HI-6100 to a standard serial port on a computer.