GE IC697PWR710 Power Supply, 120/240 VAC, 125 VDC, 50 Watts
References for Inputs–only or Outputs–only Blocks: An Inputs–only block uses one
reference in %I or %AI memory for each circuit on the block. Similarly, a block with out puts only requires one reference in %Q or %AQ memory only.
References for Blocks with both Inputs and Outputs: A block which has both inputs
and outputs uses the same number of input and output references, regardless of the
block’s actual I/O mix.
An analog block with 4 inputs and 2 outputs requires four words of analog input
memory and four words of analog output memory. The block only uses the first two
output words; however, the second two output words cannot be used for outputs be cause they cannot be assigned by the configuration software. However, they can be
used for internal registers in the application program.
References for Redundancy: The Series 90–70 PLC handles I/O data the same way for
redundant and non–redundant systems. For any redundant Bus Controller pair in the
PLC, each CPU sweep the CPU receives a one set of bus inputs and sends one set of bus
outputs. The Series 90–70 PLC does not maintain two sets of references for devices that
are set up for redundancy.
Reference Address Configuration Example
As the following examples show, it is not necessary to configure blocks in Device Num ber sequence. Device Numbers are unrelated to the assignment of Reference Addresses.
If outputs are disabled, the Bus Controller will not send output data from the CPU to the
designated device(s). Output Disable is not selectable for inputs–only devices. Inputs–only
blocks are ALWAYS sent a dummy message to turn on their I/O Enabled LEDs.
It is possible for outputs to be disabled or re–enabled using Communication Request
instructions in the application program. If this capability will be needed, then outputs
should be enabled during I/O configuration.
Ordinarily, the configuration software would be used to disable outputs that were to
remain disabled. To re–enable such inputs, it would be necessary to change the configu ration and re–store the new configuration to the PLC.
Outputs might be disabled in a system where multiple CPUs are used for distributed
control, or a system using the Series 90 PLC as an assigned monitoring device. Examples
are shown below.
Example
Selectively Disabling Outputs for Distributed Control of I/O Blocks: Some systems use
two or more CPUs on the same bus for distributed control of I/O blocks. In a distrib uted control system, each CPU sends outputs to (and receives fault reports from)
certain blocks on the bus and not others. This is accomplished by selectively enab ling or disabling outputs to the blocks.

If a block will be used in dual bus or dual controller mode, or both, set the entry for Re dundancy to YES.
If Redundancy is set ot YES for any block on a bus, the Bus Controller must also be con figured for a form of redundancy: dual bus, redundant control, or dual bus/redundant
control.
The configuration software will automatically attempt to supply a correct configuration
when you set device Redundancy to YES:
If the Bus Controller is configured for a Redundancy Mode of NONE, and you set
the Redundancy of any device on the bus to YES, the Bus Controller’s configuration
is automatically changed to Redundancy: DUAL BUS and Paired GBC: EXTERNAL.
If the Bus Controller is configured for a Redundancy Mode of either DUAL BUS or
Redundant Control (Red Ctrl), and Paired GBC is INTERNAL, each device on the
bus is automatically configured at the same bus address (Device Number) on the
redundant bus, and given the same reference addresses.
If Paired GBC is set to EXTERNAL, the block is not automatically configured on the
other bus of the pair.
If the Bus Controller is configured for a Redundancy Mode of DB/RC (dual bus/re dundant control) each device on the bus is automatically configured at the same bus
address (Device Number) on the redundant bus, and given the same reference ad dress.
Redundancy
The redundancy mode of I/O blocks is automatically matched to the Redundancy Mode
configuration of the Bus Controller;