Click to open properties box Properties - Tag_Name Parameters Tag Vis I I I I I I I I I O O Name Type Description Enable Input. If false, the instru... Boolean Input to the instruction. Boolean Input to the instruction. Boolean Input to the instruction. Boolean Input to the instruction. Boolean Input to the instruction. Boolean Input to the instruction. Boolean Input to the instruction. Boolean Input to the instruction. Enable Output. The result of ANDing all eight EnableIn In1 In2 In3 In4 In5 In6 In7 In8 EnableOut Out BOOL BOOL BOOL BOOL BOOL BOOL BOOL BOOL BOOL BOOL BOOL Value 1 1 1 1 1 1 1 1 1 0 0 Tag_Name BAND Boolean And ... 1 0 In 1 Out 1 1 1 In 2 In 3 In 4 Figure 15-96 Example of a BAND (Boolean AND) function block. Source: Image Courtesy of Rockwell Automation, Inc. • The names of the inputs and outputs are shown within the block. • The default view of the block has some but not all of the input and output parameters visible when the box is placed into the program. • The properties box, used to set the option of input and output parameters, is displayed by clicking the selection button located at the upper right hand corner of the block. • The 1 and 0 next to the inputs and outputs identify the logical state of the input and output pins for the instruction. • The dots on the input and output pins indicate BOOL type data is required. References represent tags that are linked to values stored in a controller’s memory. The two types of references, input and output, are illustrated in Figure 15-97. An input reference, or IREF, is used to receive a value from an input device or tag. An output reference, or OREF, is IREF Input references IREF IREF Figure 15-97 Input and output references. used to send a value to an output device or tag. When you use an IREF or an OREF you must create a tag or assign an existing tag to the element. You may use any of the data types for an IREF or OREF. Function blocks can be connected to other function blocks by connecting their outputs to the input of another function block using wires and pins (Figure 15-98). Wires map a signal’s path and show the flow of controller execution. Each element in a function block diagram contains pins. Elements are connected by moving wires from input pins to output pins or vice versa. The pins on the left of a function block are input pins, and those on the right are output pins. To wire two elements together, click the output pin of the first element (A) and then click the input pin of the other element (B). A green dot shows a valid connection point. Wire connectors are used to create a path without using a wire. When there are many function blocks on a sheet, or the function blocks are far apart, wire connectors used in place of wires can make the logic easier to read. OREF OREF Output references Function Block Programming Part 6 385
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