Chapter 13 PLC Logic and Bit Shift Instructions 287
and moving of the bit creates a rotate bit left function. The re-entry
process of file #B3 is displayed in the binary table in Figure 13-14.
Pressing the pushbutton at address I:1/3 resets the control register
R6:0 and sets the bit pointer to the beginning location B3:0/0.
Lost bit re-entered
Bit Shift Left (BSL); Bits are shifted to the left starting from B3:0/0 to B3:0/7.
000
End
I:1/0
T4:0/DN
Manual-Shift Pushbutton
005
EN
DN
BSL
Bit Shift Left
File #B3:0
Control R6:0
Bit Address B3:0/0
Length 8
Close input I:1/1 to create an automatic BSL.
001
I:1/1
Auto-Shift Mode
T4:0/DN
R6:0/UL
EN
DN
TON
Timer On Delay
Timer T4:0
Time Base 0:1
Preset 10
Accum 5
The bit on the far left-hand side (B3:0/7) controls the light (O:2/0).
002
B3:0/7 O:2/0
Y-LT
**Close input I:1/2 to re-enter the lost bit that comes out of the left
side (in this case B3:0/8). Therefore, creating Rotate Left.
003
I:1/2
Rotate Mode
Reset
B3:0/0
Rotate Entry Location
004
I:1/3 R6:0
RES
Figure 13-14. PLC ladder logic diagram and binary table for Example 13-4. Programming the bit shift
left (BSL) function in the LogixPro simulator.