SMAR DC302, Owner'S Operation And Maintenance Manual

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Section 2
2.1
OPERATION
The
DC302 accepts up to 16 optically isolated inputs and up to 8 open collector outputs. It is
therefore ideal for interfacing exisisting discrete points to a Fieldbus system.
An extensive Function Blocks library enables the DC302 to execute logic and functions of
regulatory and descrete control integrated via H1 Bus. Function Blocks provide great flexibility to
control strategies.
The conventional discrete I/Os work together with Fieldbus devices integrated in the same network
and in the same control loop.
Output function blocks include standard Foundation safety mechanism in case of failures.
Inputs and Outputs are isolated from each other and are accessed via communication network
through the function blocks channel. The leds are used to indicae the I/Os status. The use of
Foundation
TM
Functional Blocks make the system homogeneous in a way that the device with
convencional discrete and analog I/Os can be available in order to make the control strategies
configuration easy.
Functional Description
– Electronics
Refer to the block diagram (See Figure 2.1
–
DC302 Block Diagram ). The function of each block is
described below.
(CPU) Central Processing Unit, FRAM
The CPU is the intelligent part of the DC302 , being responsible for the management and operation
of the execution block, self-diagnosis and communication. The program and the temporary data are
stored in a FRAM memory. In the absence of energy, the data stored in the FRAM is not lost. The
FRAM memory also stores the non-volatile data that will be used later. Examples of such data are:
calibration, configuration and identification data.
Communication Controller
It monitors line activity, modulates and demodulates the signal from network line.
Power Supply
Takes power of the loop-line to power the Discrete Controller circuitry.
Factory Reset
The factory reset inscription can be found on the superior left side of the DC302 housing. In order
to accomplish this operation, simply short-circuit the contacts on the circuit board, turn-on the
DC302 in this short-circuit condition, and keep the key until the saving led goes to on state.
They are two mechanical contacts to perform the factory reset.
Input Latches
They are latches to hold the condition of inputs.
Otput Latches
They are latches to hold the condition of outputs.
Optical Isolation
Optical isolation for inputs and outputs.