GE IC698CRE020 RX7i VME 700Mhz Redundant CPU with Embedded 10/100 Ethernet
The Series 90 –70 PLC Bus Controller (catalog number IC697BEM731) is used to inter face a Genius I/O serial bus to a Series 90–70 PLC.
BUS
CONTROLLER
CPU a42453
COMMUNICATIONS
BUS
HAND–HELD
MONITOR
I/O BLOCKS
A Genius bus may serve:
Genius blocks, which provide interface to a broad range of discrete, analog, and
special–purpose field devices. Genius blocks are self–contained modules with ad vanced diagnostics capabilities and many software–configurable features.
Remote Drops, Series 90–70 I/O racks that are interfaced to the bus via Remote I/O
Scanner Modules. Each remote drop can include any mix of discrete and analog I/O
modules, providing up to 128 bytes of input data and 128 bytes of output data.
The Hand–held Monitor, which can be used as a portable device or permanently–
mounted. An HHM provides a convenient operator interface for block setup, data
monitoring, and diagnostics.
Multiple hosts, for communications using datagrams and Global Data.
A bus may feature I/O control enhanced by communications commands in the program.
Or a bus may be used entirely for I/O control, with many I/O devices and no additional
communications. Or a bus may be dedicated to CPU communications, with multiple
CPUs and no I/O devices. More complex systems can also be developed, with dual CPUs
and one or more additional CPUs for data monitoring.
Number of Bus Controllers
Up to 31 Bus Controllers can be included in a Series 90–70 PLC system with a release 3.0
or later CPU. For earlier CPU versions, the maximum number of Bus Controllers that
can be accommodated is 16. In some redundant system configurations, fewer Bus Con trollers can be used. See chapter 6 for details.

The I/O devices on a bus may be Genius I/O blocks, or standard Series 90–70 I/O mod ules in one or more remote drops.
The total number of I/O circuits that can be served by
one Genius bus depends on the types of I/O devices that are used and the memory
available in the CPU.
Memor y Required for Genius Blocks
Memory requirements for Genius I/O blocks are shown below. For %I and %Q memory,
the sizes shown are in bits. For %AI and %AQ memory, the sizes shown are in words.
Block Type
Maximum Memory Requirements
Block Type %I (bits) %Q (bits) %AI (words) %AQ (words)
115 VAC Grouped I/O blocks 8 8
115 VAC Isolated I/O blocks 8 8
16 Ckt AC Input Block 16
16 Ckt DC Sink/source blocks 16 16
32 Ckt DC Sink/source blocks 32 32
Relay Output blocks 16
4 Input/2 Output Analog Blocks 4 2
Current–source Analog I/O Blocks 4 2
Current–source Analog Output Blocks 6
RTD Input blocks 6
Thermocouple blocks 6
High–speed Counter 16 16 15
PowerTRAC Module 16 16 18
Many Genius I/O blocks have both inputs and outputs on the same block. Blocks config ured in the Logicmaster 90 software as
having both inputs and outputs will occupy iden tical references in both %I and %Q memory, regardless of the block’s
software configu ration. Unused references cannot be assigned to other inputs or outputs, and should not
be used in the application program.
Memor y Required for a Remote Drop
Together, one 90–70 Remote I/O Scanner (IC697BEM733) and the modules it serves
make up a remote drop on the Genius bus.
GENIUS BUS ALL RACKS MUST BE AT THE SAME GROUND POTENTIAL
RACK 7
UP TO 50 FEET Î
REMOTE DROP
RACK 0
The remote drop can include any mix of Series 90–70 discrete and analog input and out
put modules, up to a total of 128 bytes of inputs and 128 bytes of outputs (8 discrete
points represent one byte and 1 analog channel uses 2 bytes).