DESCRIPTION AND OPERATION
CONTROL CONFIGURATION
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I-E96-207A
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Another source of inputs is the slave module (analog or digital).
The slaves output on the expander bus to their respective mas-
ter modules. The controller module can request these inputs
from the master modules via a module bus transaction.
Valid analog ranges are 1 to 5 VDC or 4 to 20 mA. Values below
0.75 VDC cannot be digitized by the A/D circuits and must be
externally conditioned before the controller module can pro-
cess them.
Both the digital inputs and outputs use optical isolation to sep-
arate the module supplies from the field supply, thereby elimi-
nating potential ground loops in the power system.
Analog Control Station Interfacing
Analog Control Stations (IISAC01/NDCS03) allow the user to
adjust set point and control output, transfer levels of control
and select digital readout. The MANUAL/AUTO transfer station
block (function codes 21, 22, and 23) configured in the control-
ler module provides the interface for the SAC.
In the AUTO BYPASS mode, the SAC provides direct manual
control of analog outputs in the event of controller failure. In
the MANUAL BYPASS mode, the user overrides a normally
operating Controller. The controller module is able to support
up to eight daisy chained SAC (four from each station port).
Only the first SAC in a daisy chain can be used in the MANUAL
BYPASS mode. The other SACs in the daisy chain can be used
for monitoring outputs.
Module Bus Interfacing
The controller module communicates with other master mod-
ules in the processor controller unit (PCU) via the module bus.
Each master must have a unique address which is set by a
dipswitch on the module. Up to 32 modules can communicate
within one PCU. The module bus is physically located on the
multibus module unit (MMU) backplane which the modules
connect to through the P1 connector on the module.
CONTROL CONFIGURATION
Control configuration is accomplished by assigning function
codes to function blocks. The function codes are operations
such as multiply, divide, read, compare, etc. The function
blocks are addressable memory locations saved in the NVRAM
and copied to RAM for execution. Refer to the configuration
section for more information on configuring the controller
module.
