This document provides installation instructions for an IU-9100 interface unit and RP-9100 repeater. It contains warnings about safety and authorized personnel. It describes wiring the units according to codes, using ferrules on stranded wire. The IU-9100 converts RS-232 to RS-485 and the RP-9100 repeats the RS-485 signal for lines with more than 31 instruments. Connection diagrams show setting jumpers and adding line termination resistors for different configurations up to 32 units.