Appendix F: PlusBus Installation
Note:
The PlusBus is obsolete, and only required for older PlusBus Integrated Input Units and Integrated
Command Relay Units with existing installations. New systems use Plus-X Ethernet I/O.
Installing the IIU & ICRU
The Integrated Input Unit (IIU) and Integrated Command Relay (ICRU) are used to connect site
equipment to the ARC Plus. Each IIU connects up to 16 metering and 16 status channels, and each ICRU
connects 8 pairs of raise/lower relay outputs. Units are connected to the ARC Plus in daisy-chain fashion
and communicate over a digital bus using CAT5 cable. Each of four PLUSBUS ports on the ARC Plus can
connect to up 32 IIU/ICRUs, as long as there are no more than 16 IIUs or 32 ICRUs in use among all four
PLUSBUS ports. Burk Technology recommends distributing the IIUs and ICRUs across all four ports. The
maximum cable run is 50’ per port.
The IIU accepts 16 metering channels (left side of panel) and 16 status channels (right side of panel).
The ICRU accepts 8 raise and 8 lower channels.
Unit Identification
Prior to operation, each IIU and ICRU must be assigned a binary unit identifier using the rear panel dip
switches, shown below. The dip switch settings determine the assigned channel range to each IIU and
ICRU. Refer to page 109 for the settings used for each channel range. No two IIUs can have the same
identifier, and no two ICRUs can have the same identifier.
Rear panel dip switches are used to assign a binary identifier to each IIU and ICRU.
After configuring the unit identifiers, set the TERM dip switch to ON for the final unit in each PLUSBUS
chain. (If all four PLUSBUS ports are used, the TERM switch on four units will be set). It makes no
difference whether the final unit is an IIU or an ICRU. When the units are powered, the TERM LED will
illuminate for each unit identified as a terminator.
