1-12 Field Control™ Genius® Bus Interface Unit User’s Manual – October 1999 GFK-0825F
1
A Bus Interface Unit can be located on a bus stub. A Bus Interface Unit can also be located
on a bus stub, which is a short length of unterminated cable downstream of either a Genius I/O
block/Bus Switching Module combination, or a Remote I/O Scanner connected to a dual bus.
Because the bus stub cable itself is not redundant, this type of installation does not provide as
much protection as connecting directly to a dual bus. The bus switching device to which the
bus stub is connected can be an other Genius block with a Bus Swit ching Module attached, as
shown below, or a Series 90-70 Remote I/O Scanner.
In this example, there ar e two Field Control station s in stalled on a bus stub. Each is
configured as “BSM Presen t” but not configured as a “BSM C on troller”.
Bus A
Bus B
Bus
Switching
Module
Genius Block
Acting as a
BSM Controller Up to 7 Additional Devices on the Bus Stub
46474
Up to seven devi ces (not coun ting the BSM/bl ock or Remote I/ O Scanner to wh i ch the dual bus i s
connected) can be installed on a bus stub. Each device on a bus stub counts toward the total of 32
devices on the Genius bus.
Restricti on s on the number a n d length of bus st ubs that may be us e d on a dual bus ar e explained in
the Genius I/O System and Communications User's Manual.