Delta Electronics Programmable Logic Controller DVP-PLC - Manual (Page 267)

6 Application Instructions API 00-49
DVP-PLC Application Manual 6-55
API Mnemonic Operands Function
38 SFWR P Shift Register Write
Controllers
ES/EX/SS SA/SX/SC EH/SV
Bit Devices Word Devices Program Steps Type
OP X Y M S K H KnX KnY KnM KnS T C D E F
S * * * * * * * * * * *
D * * * * * *
n * *
SFWR, SFWRP: 7 steps
PULSE 16-bit 32-bit
ES EX SS SA SX SC EH SV ES EX SS SA SX SC EH SV ES EX SS SA SX SC EH SV
Operands:
S : Device of stack data written in D: Start No. of stack data n: Length of stack data
Explanations:
1. Range of n : 2 ~ 512
2. See the specifications of each model for their range of use.
3. Flag: M1022 (carry flag)
4. The stack data of n words starting from D are defined as “first-in, first-out” stack data and designate the first
device as the pointer. When the instruction is executed, the content in the pointer pluses 1, and the content in
the device designated by S will be written into the designated location in the “first-in, first-out” stack data
designated by the pointer. When the content in the pointer exceeds n - 1, this instruction will not process any
new value written in and the carry flag M1022 = On.
5. This instruction adopts pulse execution instructions (SFWRP)
Program Example:
1. Pointer D0 is reset as 0. When X0 = Off→On, the content in D20 will be sent to D1 and the content in pointer D0
becomes 1. After the content in D20 is changed, make X0 = Off→On again, and the content in D2 will be sent to
D2 and the content in D0 becomes 2.
2. The figure below illustrates the shift and writing in 1~2 execution of the instruction.
n The content in D20 is sent to D1.
o The content in pointer D0 becomes 1.
X10
RST D0
D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 D20
X0
SFWRP D20 K10 D0
pointer
n = 10 points
D0 = 3 2 1
Reset the content of D0 as 0 in advance
Remarks:
This instruction can be used together with API 39 SFRD for the reading/writing of “first-in, first-out” stack data.