ENGINEERING LOGIC DIAGRAMS
Figure 3 Basic Logic Symbols
Figure 4 Conventions for Depicting Multiple Inputs
The AND gate has a common variation called a COINCIDENCE gate. Logic gates are not
limited to two inputs. Theoretically, there is no limit to the number of inputs a gate can have.
But, as the number of inputs increases, the symbol must be altered to accommodate the
increased inputs. There are two basic ways to show multiple inputs. Figure 4 demonstrates
both methods, using an OR gate as an example. The symbols used in Figure 4 are used
extensively in computer logic diagrams. Process control logic diagrams usually use the
symbology shown in Figure 2.