Codan NGT 2010 RF Technical & Service Manual page 658

NRI—Technical description
NRI User Connect PCB
The main function of the NRI User Connect PCB is to physically support the connectors.
The NRI has two power connectors, two CIB connectors, a standard serial port
(providing the modem interface) and a test port, which provides a connection point for
factory testing and future use. The NRI User Connect PCB also provides some
input/output filtering, power switching, and level translation for the RS232 serial
interfaces.
264 NGT Transceiver System Technical Service Manual