GE GFK-0787B Noise Reduction Machine User Manual


 
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1-7GFK-0787B Chapter 1 Introduction
PLC Subsystem: Providing Output Data
Running the same application program, each PLC (referred to here by Genius Bus
Controller (GBC) serial bus addresses: 31, 30, and 29) processes the voted input data and
produces appropriate outputs. Because each of the three PLCs is running the same
program, they produce three copies of the same output data.
Each PLC then sends this triplicated output data on the bus.
output 1
output 1 output 1
GBC 31
GBC 31
GBC 31
GBC 30
GBC 30
GBC 30
GBC 29
GBC 29
GBC 29
PLC A PLC CPLC B
Output Subsystem
The basic element of an output subsystem is the output group. Each block in the group
has the same reference address in the application program, so each block receives the
same output data.
The output group votes on the three outputs and uses the result as the physical output.
In this example, communications are lost on bus C. Upon losing communications, the
block on bus C follows its configuration instructions, which are to default its outputs to 0.
However, the remaining blocks in the group continue to receive valid output data from
all three PLCs over busses A and B, and the actual state of the output load is controlled
properly. The loss of block or loss of bus diagnostic would be recorded, providing an aid
to troubleshooting and annunciating the problem.
C
output 31
1
1
1
voted
output
1
output 30
output 29
output 31
1
1
1
1
output 30
output 29
voted
output
output 31
1
1
1
1 output 30
output 29
voted
output
Load
AB
0
default
output
AB
CD
In a 4-block output group, each field output is supported by two Genius source outputs
connected in parallel on one side of the actuator and two Genius sink outputs connected
in parallel on the other. Each block in the group receives outputs from each of the three
separate processors.
Automatic System Test
Optional autotest routines test the complete system from input modules through to
output modules, including failures in the I/O wiring. Autotesting does not affect the
normal state of field devices.