relay ladder logic control systems - university of alabama
TRANSCRIPT
![Page 1: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/1.jpg)
Relay Ladder Logic Control Systems
![Page 2: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/2.jpg)
Ladder Logic Control
► Logic control is used with relatively simple ON/OFF systems - like pneumatics
PB-1 CR-1
CR-1A
CR-1B
LS-1
SOL-A
LS-1
Sol. A
120 VAC
Pneumatic System Relay Ladder Logic(RLL) Control
![Page 3: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/3.jpg)
Logic Control Components
PB-1 CR-1
CR-1A
CR-1B
LS-1
SOL-A
120 VAC
![Page 4: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/4.jpg)
Control Relay - Not Activated
Common
NC contact
NO contact
no current throughcoil
"control relay" not activated
Vpower
![Page 5: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/5.jpg)
Control Relay - Activated
Common
NC contact
NO contact
current flowingin coil
"control relay" activated
Vpower
![Page 6: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/6.jpg)
Normally Open Schematics
y p ( )
Limit Switch
MomentaryContactPushbutton
PressureSwitch
ManualSwitch
Contacts
![Page 7: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/7.jpg)
Normally Closed Schematics
PressureSwitch
Limit Switch
MomentaryContactPushbutton
ManualSwitch
Contacts
![Page 8: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/8.jpg)
Output Schematics
ControlRelay Coil
SolenoidCoil
Annunciator(Horn)
Lamp
![Page 9: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/9.jpg)
Why is it called “Logic Control?”
IF _______________ AND _______________THEN ____________________
PB-1 LS-2 SOL-2
IF there is continuity acrossthe inputs
![Page 10: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/10.jpg)
“OR” Example
IF __________________ OR ______________THEN ___________________
PB-1CR-6
LS-1
![Page 11: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/11.jpg)
Write the Logic for this Rung
IF { _______________ AND _______________ }OR { _______________ AND _______________ }THEN ____________________
SOL-5
CR-7 LS-4
PB-2PB-1
![Page 12: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/12.jpg)
“One Shot” - Single Stroke
►Pressing the pushbutton PB-1 will cause the cylinder to extend and retract one time
Pneumatic System “Ladder” Logic Control
Sol. A LS-1
120 VAC
PB-1 CR-1
CR-1A LS-1
CR-1B SOL-A
![Page 13: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/13.jpg)
“One Shot” - Step #1
► Pressing the momentary contact pushbutton PB-1 energizes the control relay CR-1
Sol. A LS-1
120 VAC
PB-1 CR-1
CR-1A LS-1
CR-1B SOL-A
![Page 14: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/14.jpg)
“One Shot” - Step #2
► After control relay CR-1 energizes, normally open contacts CR-1A and CR-1B activate
Sol. A LS-1
PB-1 CR-1
120 VAC
CR-1A LS-1
CR-1B SOL-A
![Page 15: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/15.jpg)
“One Shot” - Step #3
► Control relay CR-1 is now energized by a 2nd path, solenoid SOL-A also activates
Sol. A LS-1
PB-1 CR-1
120 VAC
CR-1A LS-1
CR-1B SOL-A
![Page 16: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/16.jpg)
“One Shot” - Step #4
► PB-1 is released, but control relay CR-1 is still energized by the 2nd path (“hold” circuit)
Sol. A LS-1
120 VAC
PB-1 CR-1
CR-1A LS-1
CR-1B SOL-A
![Page 17: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/17.jpg)
“One Shot” - Step #5
► Solenoid A shifts the valve spool to the right, and the cylinder begins to extend
LS-1Sol. A
120 VAC
PB-1 CR-1
CR-1A LS-1
CR-1B SOL-A
![Page 18: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/18.jpg)
“One Shot” - Step #6
► Cylinder activates the normally closed limit switch LS-1, which “kills” the hold circuit for control relay CR-1 120 VAC
LS-1Sol. A
PB-1 CR-1
CR-1A LS-1
CR-1B SOL-A
![Page 19: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/19.jpg)
“One Shot” - Step #7
►With control relay CR-1 de-activated, the contacts CR-1A and CR-1B return to their normally open state 120 VAC
LS-1Sol. A
PB-1 CR-1
CR-1A LS-1
CR-1B SOL-A
![Page 20: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/20.jpg)
“One Shot” - Step #8
► CR-1B is now open, SOL-A is de-activated, spring returns valve to default state
Sol. A LS-1
120 VAC
PB-1 CR-1
CR-1A LS-1
CR-1B SOL-A
![Page 21: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/21.jpg)
“One Shot” - Step #9
► Cylinder begins to retract, and “rolls off” of LS-1, which returns to its N.C. state
Sol. A LS-1
120 VAC
PB-1 CR-1
CR-1A LS-1
CR-1B SOL-A
![Page 22: Relay Ladder Logic Control Systems - University of Alabama](https://reader031.vdocuments.us/reader031/viewer/2022021207/620626768c2f7b173004e593/html5/thumbnails/22.jpg)
“One Shot” - Step #10
► Cylinder fully retracts and system has returned to the start-up configuration
Sol. A LS-1
120 VAC
PB-1 CR-1
CR-1A LS-1
CR-1B SOL-A