ISPSoft User Manual 7.3 Using a Function Block 7.3.1 Basic Specifications for Function Blocks The specifications for the function blocks in ISPSoft are shown below. When users use function blocks, they have to make sure that the operation conforms to the specifications in the table. Otherwise, an error occurs when the program is compiled or executed. Specifications for the function blocks Note The pins of a function block must be assigned operands. The operands can be device addresses or symbols. If the class of a symbol is VAR_INPUT, the operand assigned to the symbol can be a constant.
An inferior function block can not call the superior function block, and a function block can not call itself. If a function block is exported, the definition of the function block is exported, but the definitions of the inferior function blocks and the global symbols used are not exported. and instruction lists must be connected to contacts. However, the En pins of the function blocks in structured The En pins of the function blocks in ladder diagrams, sequential function charts, function block diagrams, texts do not have to be connected to contacts.
The programming languages which support the creation of function blocks include ladder diagrams, instruction lists, structured texts, function block diagrams and continuous function charts. Sequential function charts do not support the creation of function blocks. 7-32 Number of function All series: no limitation block definitions Number of function block instances AH5X1/ AH560 Redundancy System / AHxxEMC/AS: Depends on the controller devices available. AH5X0: The maximum number of memory block instances varies according to the series (Please refer to appendix B).Depends on the controller devices available. DVP: Depends on the controller devices available.
Size of a function block AH5X1/ AH560 Redundancy System/AS: Without limit, until the internal memory is used up. AH5X0: The size of a memory block instance is 4096 words. DVP: Depends on the devices assigned to the function block. Number of layers For AH series, the nest structure of function block calling function block, maximum layer is 32 ; AS/DVP series, maximum layer is 16; DVPxxMC/ AS5xx series does not have limit.