LAB REPORT NO.5
INTRODUCTION TO JUMPING
Upon completion of this lab, one will be able to
Understand jumping instruction and how it work in plc ladder diagram.
Use status bits of counters, timers to control other instructions.
Design example in Online PLC Simulator.
2- PLC Control Instructions
Control instructions are used to enable or to disable a block of the ladder logic program or to
move the execution of a ladder logic program from one place to another place. The control
instructions discussed in this module include the following:
Jump To Label (JMP), instruction format:
Label (LBL), instruction format:
2-1. Jump and Label Instructions
Normally, a PLC executes a ladder logic program in a rung by rung sequence. Jump instruction
is a controlled output instruction that allow a PLC to break this sequence and to move the
program execution to another rung.
Fig.1 Jump instruction
The Jump to Label instruction and the Label instruction are used in combination to redirect the
execution of a ladder logic program. The Jump to Label instruction is a controlled instruction;
when its rung is false, the PLC scans the next rung. When the rung of a Jump to Label instruction
is true, the PLC breaks its sequence execution and moves to the rung with a Label instruction
that has the same label number as the Jump to Label instruction. When a Label instruction is
used, it is always the first (most left) instruction in a rung. It does not cause its rung to be true or
false; it only shows the location of the label.
jump forward or backward.
use multiple jump to the same label.
Jumps within jumps are possible.
2-2. Advantages of Jump:
Allows the PLC to hold more than one program.
Sections of a program can be jumped when production fault occurs.
Reduces processor scan time, allowing more scans to take place within a given period of
Program information is updated more frequently.
2-3. In Online PLC Simulator:
Jump Instruction JMP:
Label Instruction LBL:
Task . 1
To design such a system, we will require switches, counters, timers and output coils.
Fig.2 Parking system.
Ladder logic allows this function to be represented this way. Fig.2 shows the actual way in which
the process takes place.
To implement this using ladder logic, we needed NO and NC contacts, timer on-delay instruction
TON, timer off-delay instruction TOFF, UP counters CTU and output coils.
Press the master switch and control system will start operating.
Initially green signal of road-1 is ON and remain ON for 20 seconds, meanwhile the
road-2 has red signal.
After 20sec, road-1 green signal turns off, and red signal gets ON, at the same time road-
2 red signal turns off, and green signal turns ON.
When the green led of any of road gets on, pressing the "Door-1 Open ", car will enter
into parking and the counter value is incremented on the entry of each new car.
After entering the park, pressing the "Door-1 Close” from inside will close the door.
When the parking capacity is maximum i.e. 10, "Parking-1 Full" light will turn on.
Now no more cars will enter the parking lot, and the door will not open for any new car.
Similarly for Parking-2, above 4 steps will repeat.
Setting the timer:
Set Accumulator value equal to zero. Find the preset value and time base value for given time-
delay. If and
Setting the counters:
Set Accumulator value equal to zero. Also set the preset value required.
Login plcsimulator.net and form the ladder logic as:
Addressing the components
I/O Switches Addresses
Master Switch I/0
Parking-1 Full O/3
Parking-2 Full O/4
Timer-ON Used T/1
Timer_OFF Used T/0
Door-1 Open I/2
Door-1 Opening Motor O/5
Door-1 Closing Motor O/6
Door-1 Close I/3
Counter for cars in Parking-1 C/1
Door-2 Open I/4
Door-2 Close I/5
Counter for cars in Parking-2 C/0
Door-2 Opening Motor O/7
Door-2 Closing Motor O/8
Fig.3: I/O panel
To start the simulation, click on RUN. As program starts running, verify the conditions:
Master switch is pressed green signal of road-1 turns on meanwhile signal of road-2 turns
red and T/1 starts and gives a delay of 20 sec.
During 20 sec delay of Green On, Open button is pressed, opening motor will open the
door and car starts entering.
When parking lot reaches its maximum capacity, Door will not open.
Desired system is achieved.
Above simulation & ladder diagram show the logic is correct.