Chapter 3: Configuration 3.6 Setting the Configuration
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• If an available block has no valid outputs, no outputs of that block are made
available for connection.
• If a valid output belongs to a block which is not available, it is not made
available for connection.
• The same signal can be shared between several function blocks.
• Blocks may be combined to produce more complex logic functions.
If an output of an Output Function block (OF) is referenced and then the Type
parameter setting of the (OF) block is changed, references to outputs of that block
will become invalid. The input referencing the invalid output will show the
following connection information:
Example
Suppose a connection has been made between an output of block A and an input
of block B. Then suppose block A is switched OFF. Now this B input is connected
to an output whose value is undefined.
In this situation, when block B is executed and the input above requests a value
from the A output, the controller will continue to execute, and the following will
happen:
1 The A output signals to the error handling system that it has been
erroneously referenced
2 The A output returns a predefined value to the B input enabling the B block
to complete its calculations. All analog outputs have the “off value” 0.0, and
all digital outputs have the “off value” False.
If the input to a block is OFF, it represents a value to this block that is neutral to
the function of that block.
Notes:
• Any analog input of any block type can be connected to any analog output of
any block type.
AO1: Ana Out 1
Signal
OF1[Analog.Invalid]
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