Chapter 11 Function Block Diagram 11.2.1 Input Nodes and Output Nodes The devices and the symbols in a function block diagram are represented by nodes. An input node and the corresponding output node must conform to the rules listed below. (a) One node represents an M/S/T/C/HC device, and the other node represents a symbol whose data type is BOOL/STEP/TIMER/COUNTER. (The device assigned to the node which represents a symbol is a bit device.) (b) One node represents a D/L device, and the other node represents a symbol whose data type is not BOOL/STEP/REAL/STRING.
(c) One node represents a T/C device, and the other node represents a D/L device or a symbol whose data type is WORD/INT/TIMER/COUNTER. (d) One node represents a D/L/HC device, or a symbol whose data type is COUNTER, and to which a HC device is assigned. The other node represents a symbol whose data type is DWORD/DINT. (e) One node represents a symbol whose data type is WORD/DWORD/LWORD, and the other node represents a symbol whose data type is INT/DINT/LINT. The data length of the output node must be larger than or equal to the data length of the input node. (f) Both nodes represent symbols whose data types are REAL/LREAL/STRING. The data lengths of the nodes must be the same.
(g) If an input node has multiple output nodes, the output nodes must conform to the rules listed above. 32 output nodes at most form a group. After users add an output node rightward, they can create another group of output nodes. Graphical representation Example Example 1: The state of the contact M0 is sent to M1. Example 2: The data in D0 is sent to D1. 11-7