Chapter 7 Function Block and Library The programming languages which support the calling of function blocks include ladder diagrams, instruction lists, structured texts, function block diagrams and continuous function charts. Users can also use function blocks in the actions in sequential function charts. Users can modify function block definitions, but they can not modify function block instances.
(Please refer to section 7.3.4.) If the modification of a function block definition in the online mode results in the abnormal representation of the function block in the superior POU, users have to disable the online editing function, delete the abnormal representation of the function block, and add the normal representation of the function block. After the normal representation of the function block is added, the program can be compiled and downloaded.
(Please refer to section 7.3.4 for more information.) If a jump instruction is used in a function block, the jump destination must be in the same function block, and can not be outside the function block or in the inferior function block. Users can not declare symbols whose data types are TIMER and symbols whose data types are COUNTER in the function blocks in a project for an AH/AS series CPU module, but they can declare symbols whose data types are POINTER, symbols whose data types are T_POINTER, symbols whose data types are C_POINTER, and symbols whose data types are HC_POINTER.
Pulse instructions such as MOVP and CML can not be used in the function blocks in a project for an AH/AS series CPU module. LDP/ANDP/ORP, LDF/ANDF/ORF, PLS, PLF, NP, PN, MC, MCR, and GOEND can not be used. AH/AS series CPU modules provide special pulse instructions which can be used in function blocks. Please refer to the following section for more information. *1. Please refer to section 5.4.1 for more information about creating a POU of the function block type, and section 6.2.2 for more information about declaring a function block instance. *2. Please refer to chapter 10~chapter 15 for more information about calling function blocks. 7-33