Ladder Diagram to control light as emergency signal with hooter
Program Description
File; #N7:0 and File length is 2, hence output sequence is varied from N7:0 and N7:1 with each input.
Destination is set to O:2 hence with each transition, N7:0 and N7:1 are moved to O:2 with masking.
O:2/0 and O:2/1 are used as the output address to Emergency Light and a Hooter, hence Mask has value
0003h which means data flow of N7:0/0, N7:0/1, N7:1/0 and N7:1/1 are passed to O:2/0 and O:2/1, and
remaining bits are blocked.
Control parameters are assigned to register R6:0.
Sequence of Light and Hooter to be operated are stored in the registers N7:0 and N7:1 as following.
Time base is set to 1sec, hence after every 1sec, output sequence is changed to its next register pattern
output which is then transferred to O:2 and O:2/0-O:2/1 are energized accordingly.
As we can see, N7:1 and N7:2 have the exact opposite bit pattern. So, these bits are set to 1 for 1 cycle and
reset for the next cycle. These bits are used to operate Hooter and a Light.
So when I:1/0 is pressed, during position 0, outputs and remain in OFF condition and are energized when
SQO is at position 1.
When Stop PB with address I:1/1 is pressed, Position is reset to 0 and all the outputs are de-energized.
Runtime Test Cases
PLC Program to Measure Time Taken by an Event
This is a PLC Program to Measure Time Taken by an Event.
Problem Description
There are certain objects moving on conveyor belt. Time of an object to reach from one end to another
end of the conveyor is to be measured. Implement this in PLC using Ladder Diagram programming
language.
Problem Diagram
Problem Solution
Install two proximity switches, one at the head end and another at the tail end.
When first proximity detects an object, it latches and output starting timer.
When another proximity placed at the tail end detects the same object, timer is stopped.
Move preset value to any register or output displays.
This shows time taken by an event.
Similar phenomena can be applied to measure time taken to fill an empty tank.
PLC Program
Here is PLC program to Measure Time Taken by an Event, along with program explanation and run time
test cases.
List of Inputs and Outputs
I:1/0
= Start Measurement
(Input)
I:1/1
= Stop Measurement
(Input)
I:1/2
= Head proximity
(Input)
I:1/3
= Tail Proximity
(Input)
T4:0
= Retentive Timer to measure time (Timer)
N7:0
= Register to store measured time (Register)
O:6
= (Display) To display measured time
(Output)
-(RES)- = Reset Retentive timer
(Reset)
|
