Chapter 6 Applied Instructions 6.25.2 Explanation of Task Control Instructions Symbol: S 1 ： Name of the SFC POU S 2 ： Function code Word S 3 ： Device address Explanation: 1. The designated SFC program of S 1 will be activated according to the setups of S 2 . 2. When the instruction is executed, the SFC POU designated by S 1 will be activated only when the SFC POU is being scanned. 3. Operand: S 1 defines the name of the SFC POU. When the designated SFC POU of S 1 is executed, the parameters such as SFC/STEP/ACTION/TRANSITION of the SFC program will be cleared when S 2 =0 or 1, and the execution will start according to the value specified in S 2.
S 2 =0, the system will execute the SFC POU from the initial Step. S 2 =1, the system will execute the SFC POU from the designated Step of S 3 . S 2 =2, the status and the parameters such as SFC/STEP/ACTION/TRANSITION of the SFC will NOT be cleared and the system will start executing from where it pauses. S 3 designates the step to be started in the SFC program of S 1 . 4. The range of S 2 is 0 to 2. When it is out of range, it will be seen as 0. 5. When the state of the SFC POU is RUN, executing this instruction is invalid. Example: Set up one LD(ladder) POU and specify its POU name as Main, and 2 SFC POUs with the names of TestSFC1 and TestSFC2. 1.
When the program is executed (RUN), TestSFC1 and TestSFC2 will execute the SFCSTP, and 2 SFC POUs will stop executing. 2. When M0 is set from OFF to ON, TestSFC1/ TestSFC2 POU will execute the SFCRUN* instructions. Refer to the contents of TestSFC1 and TestSFC2 for execution details of the 2 POUs. When S 2 is set to 0, the status and the parameters of the SFC will be cleared and will 6-543 API Instruction code Operand Function 2500 SFCRUN S , S , S 1 2 3 SFC Run Device X Y M S T C HC D L SM SR E K 16# “$” DF S S 2 S 3 Pulse instruction 16-bit instruction (7 steps) 32-bit AH500 -