3 . I ns t r uc ti on Se t3- 9 9API Mnemonic Operands Function ControllersES2/EX2 SS2 SA2SE SX238 SFWR P Shift Register WriteTypeOPBit Devices Word devices Program StepsX Y M S K H KnX KnY KnM KnS T C D E F SFWR, SFWRP: 7 stepsS * * * * * * * * * * *D * * * * * *n * *PULSE 16-bit 32-bitES2/EX2 SS2 SA2SE SX2 ES2/EX2 SS2 SA2SE SX2 ES2/EX2 SS2 SA2SE SX2Operands:S: Source device D: Head address of data stack n: Length of data stackExplanations:1. This instruction defines the data stack of n words starting from D as a “first-in, first out (FIFO)”data stack and specifies the first device as the pointer (D). When SFWRP is executed, contentin pointer pluses 1, and the content in S will be written into the device designated by thepointer. When the content in pointer exceeds n-1, the instruction stops and carry flag M1022=ON.2. This instruction is generally used in pulse execution mode (SFWRP).3. Valid range of operand n: 2≤ n ≤512Program Example:1. First, reset the content of D0. When X0 goes from OFF to ON, the content of D0 (pointer)becomes 1, and D20 is written into D1. If the content of D20 is changed and X0 is triggeredagain, pointer D0 becomes 2, and the content of D20 is then written into D2.2. P The figure below illustrates the shift and writing process of the instruction. The content of D0 becomes 1.. The content of D20 is written into D1.X20RST D0D9 D8 D7 D6 D5 D4 D3 D2 D1 D0D20X0SFWRP D20 K10D0Reset the content of D0 to 0 (zero) previouslyPointern = 10 pointsD0 = 3 2 1Points to note:This instruction can be used together with API 39 SFRD for the reading/writing of “first-in, first-out”stack data.
