Siemens Simatic S7-200 System Manual page 263

First-In-First-Out
L
A
EN
D
TABLE
S
T FIFO TABLE, DATA
L
212 214
First-In-First-Out Example
I4.1
VW200
Before execution of FIFO
VW200
VW202
VW204
VW206
VW208
VW210
VW212
VW214
Figure 10-28
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02
The First-In-First-Out instruction removes the first entry in the
table (TABLE), and outputs the value to a specified location
FIFO
(DATA). All other entries of the table are shifted up one location.
The entry count in the table is decremented for each instruction
OUT
execution.
DATA
Operands:
215 216
This instruction affects the following Special Memory bits:
SM1.5 is set to 1 if you try to remove an entry from an empty
table.
LAD
FIFO
EN
TABLE
DATA VW400
Application
0006 TL (max. no. of entries)
0003 EC (entry count)
5431 d0 (data 0)
8942 d1 (data 1)
1234 d2 (data 2)
xxxx
xxxx
xxxx
Example of First-In-First-Out Instruction
TABLE: VW, T, C, IW, QW, MW, SMW, *VD,
*AC, SW
DATA: VW, T, C, IW, QW, MW, SMW, AC,
AQW, *VD, *AC, SW
STL
LD I4.1
FIFO VW200, VW400
After execution of FIFO
VW400
5431
VW200 0006 TL (max. no. of entries)
VW202 0002 EC (entry count)
VW204 8942 d0 (data 0)
VW206 1234 d1 (data 1)
VW208 xxxx
VW210 xxxx
VW212 xxxx
VW214 xxxx
Instruction Set
10-75