GE Industrial Solutions Entellisys System User Manual - Manual (Page 161)

FlexLogic example 161
11
In the example below, it is assumed that logic has already been programmed to produce Virtual
Outputs 1 and 2, and is only a part of the full set of equations used. When using FlexLogic, it is
important to make a note of each virtual output used—a virtual output designation (1 to 128)
can only be properly assigned once.
Figure 11-1 Example logic scheme
1. Inspect the logic diagram to determine if the required logic can be implemented with the
FlexLogic operators. If this is not possible, the logic must be altered until this condition is
satisfied.
a. Count the inputs to each gate to verify that the number of inputs does not exceed the
FlexLogic limits, which is unlikely but possible. If the number of inputs is too high,
subdivide the inputs into multiple gates to produce an equivalent. For example, if 25
inputs to an AND gate are required: connect Inputs 1 through 16 to AND (16); 17 through
25 to AND (9); and the outputs from these two gates to AND (2).
b. Inspect each operator between the initial operands and final virtual outputs to determine
if the output from the operator is used as an input to more than one subsequent
operator. If so, the operator output must be assigned as a virtual output.
For example, in Figure 11-1, the output of the AND gate is used as an input to both OR#1
and Timer 1, and must therefore be made a virtual output and assigned the next
available number (i.e., Virtual Output 3). The final output must also be assigned to a
virtual output (Virtual Output 4), which will be programmed in the contact output section
to operate relay H1 (i.e., Output Contact H1).
Therefore, the required logic can be implemented with two FlexLogic equations with
outputs of Virtual Output 3 and Virtual Output 4 as shown below in Figure 11-2.
Figure 11-2 Logic example with Virtual Outputs