Page 295 - Programmable Logic Controllers, Fifth Edition - Mobile version

L1 Inputs Ladder logic program Outputs L2
Data_Stack_Load
<Local:1:I.Data.0> LED display
FFL Data_Stack_Output[0]
Data_Stack_Load FIFO Load EN <Local:6:O.Data> 0000
Source Data_Stack_Input
FIFO Data_Stack_Array[0] DN
Data_Stack_Unload Control Data_Stack_Status EM
Length 5
Data_Stack_Input Position 0
0 0 2 3 <Local:5:I.Data> Data_Stack_Unload
Thumbwheel switch <Local:1:I.Data.1>
FFU
FIFO Unload EN
FIFO Data_Stack_Array[0] DN
Dest Data_Stack_Output
Control Data_Stack_Status EM
Length 5
Position 0
Figure 12-39 ControlLogix FIFO instruction pair.

• The data stack is capable of containing 5 words. • The Data_Stack_Load input pushbutton is used to
• It takes values from the input thumbwheel switch load the decimal numbers into the array.
and stores them in the data stack array. • The output module is used to display the decimal
• The values can be pulled from the stack in numbers and represents the destination address.
a FIFO order and sent to the stack output • The Data_Stack_Unload input pushbutton is used to
location. trigger the FIFO unload operation.

276 Chapter 12 Sequencer and Shift Register Instructions

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