The RS-I is normally wired DCE. This allows it to connect directly to a PC (or similar device) with a straight cable. If you need to connect to a DCE device, you can get inexpensive "NULL MODEM" adapters or you can cut traces on the PC board and connect wires to cross pins 2 and 3 of the DB9 and, if used, pins 7 and 8. The latest PCB has holes specifically designed to help you make this modification.