Chapter 6 PLC Programming 137
Press the Green Pushbutton (GPB) to turn the Green Pilot Light (G-PLT) on.
Press the GPB again to turn the G-PLT off.
000
001
002
B3:0/0
Previous State
End
I:1/0
GPB
I:1/0
GPB
I:1/0
GPB
I:1/0
GPB
O:2/0
G-PLT
O:2/0
G-PLT
B3:0/0
Previous State
B:0/0
Previous State
O:2/0
G-PLT
Figure 6-42. PLC ladder logic diagram for Example 6-5. Using one input to toggle an output between
on and off.
Example 6-5
Figure 6-42 shows the interlocking contacts arrangement of an output and a bit. Pressing
the green pushbutton (GPB) at address I:1/0 turns on the G-PLT output light at address O:2/0.
Pressing the same button again turns off the light. The B3:0/0 bit retains the previous state of
the G-PLT output at address O:2/0. Therefore, the B3:0/0 bit allows the use of a single input
(GPB at I:1/0) to toggle the output O:2/0 back and forth between on and off states.