Ladder program elements to deal with active high and/or active low input devices This presentation is partially animated. Only use the control panel at the bottom of screen to review what you have seen. When using your mouse, make sure you click only when it is within the light blue frame that surrounds each slide.

Integrating the field devices with a programmable controller and then creating the program that operates the field devices is a critical task. “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts Simple Programmable Controller that has two input modules and two output modules Note the different voltage rating for the modules. Other modules with different voltage rating are available. Input ModulesOutput Modules

Motor Starter To FCE motor 120 volts N.O. Simple Programmable Controller that has two input modules and two output modules Note the different voltage rating for the modules. Other modules with different voltage rating are available. Input devices Output device “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts Input ModulesOutput Modules N.O.

Input devices If this were a Temperature Sense High alarm device would it have an active high or active low output? The challenge is not in attaching the wires to an assigned address (terminal) at the appropriate module. 24 volts N.O. TSH (active low) The important thing is to know if the devices are wired to be active high or active low so you can pick the proper programming element for your ladder program. N.O. “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts Input ModulesOutput Modules Motor Starter To FCE motor 120 volts Output device

The challenge is not in attaching the wires to an assigned address (terminal) at the appropriate module. 120 volts What about this Start push button? N.O. “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts Input ModulesOutput Modules If this were a Temperature Sense High alarm device would it have an active high or active low output? 24 volts N.O. TSH (active low) Motor Starter To FCE motor 120 volts Output device

The challenge is not in attaching the wires to an assigned address (terminal) at the appropriate module. 120 volts N.O. “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts Input ModulesOutput Modules 24 volts N.O. TSH (active low) Motor Starter To FCE motor 120 volts Output device Start P.B.

The challenge is not in attaching the wires to an assigned address (terminal) at the appropriate module. Motor Starter To FCE motor 120 volts Output device 120 volts N.O. “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts Input ModulesOutput Modules 24 volts N.O. TSH (active low) Start P.B. Now lets attach the output device

The challenge is not in attaching the wires to an assigned address (terminal) at the appropriate module. Motor Starter To FCE motor 120 volts Output device 120 volts N.O. “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts Input ModulesOutput Modules 24 volts N.O. TSH (active low) Start P.B. Now lets attach the output device

Ladder Program O-0,1 I-0,0I-1,3 TSH Start P.B. Motor Starter To FCE motor 120 volts Output device 120 volts N.O. “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts Input ModulesOutput Modules 24 volts N.O. TSH (active low) Start P.B. Rule of Thumb for programmable logic controllers “When the computer inside a programmable logic controller senses that an input address is at “logic 1” the computer changes the symbol you put into your program and then executes the ladder program rung.” Next, we write a ladder program to control this motor.

Ladder Program Motor Starter To FCE motor 120 volts Output device 120 volts N.O. “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts Input ModulesOutput Modules 24 volts N.O. TSH (active low) Start P.B. “When the computer inside a programmable logic controller senses that an input address is at “logic 1” the computer changes the symbol you put into your program and then executes the ladder program rung.” If the input device attached at input address I-0,0 is passive, (a) Will the programmable control change the symbol that is associated with input address I-0,0 ? YES ! O-0,1 I-0,0I-1,3 TSH Start P.B.

Ladder Program Motor Starter To FCE motor 120 volts Output device 120 volts N.O. “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts Input ModulesOutput Modules 24 volts N.O. TSH (active low) Start P.B. “When the computer inside a programmable logic controller senses that an input address is at “logic 1” the computer changes the symbol you put into your program and then executes the ladder program rung.” If the input device attached at input address I-1,3 is passive, (a) Will the programmable control change the symbol that is associated with input address I-1,3 ? YES ! O-0,1 I-0,0I-1,3 TSH Start P.B.

“We-build-them” Programmable Controllers I-0,3 O-0,3 WBT-4 I-1,3 O-1,3 24 volts120 volts 48 volts 24 volts TSH N.O. motor Starter To motor and FCE 120 volts N.O. (active high) (active low) Notice how this wiring of the temperature alarm input device is different than the previous example. Start P.B.

“We-build-them” Programmable Controllers I-0,3 O-0,3 WBT-4 I-1,3 O-1,3 24 volts120 volts 48 volts TSH N.O. motor Starter To motor and FCE 120 volts N.O. (active high) (active low) Notice how the program symbol for the TSH is also different as well. Program for previous active low wired temperature sense high alarm device. Start P.B. Old New You put this symbol into your program so the computer can change it to the other symbol when the terminal I-0,0 changes from logic “0” to logic “1”. O-0,1 I-0,0I-1,3 TSH Start P.B. O-0,1 I-0,0I-1,3 TSH Start P.B. 24 volts TSH

“We-build-them” Programmable Controllers O-0,3 WBT-4 I-1,3O-1,3 120 volts 48 volts motor Starter To motor and FCE I-0,3 24 volts TSH N.O. 120 volts N.O. (active high) (active low) “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts120 volts 48 volts motor Starter To motor and FCE Start P.B. 24 volts TSH N.O. 120 volts N.O. (active low) Notice how the wiring of the TSH input devices are different. Notice how the program elements are different as well. Start P.B. O-0,1 I-0,0I-1,3 TSH Start P.B. O-0,1 Ladder Program I-0,0I-1,3 TSH Start P.B.

O-0,1 Ladder Program I-0,0I-1,3 TSH Start P.B. “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts motor Starter To motor and FCE 120 volts 24 volts TSH N.O. 120 volts N.C. (active high) Study this example and write the program before you go on. Start P.B.

Ladder Program “We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts motor Starter To motor and FCE 120 volts TSH N.O. (active high) Now try this one. 24 volts 120 volts N.C. (active low) Start P.B. O-0,1 I-0,0I-1,3 TSH Start P.B.

“We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 motor Starter To motor and FCE 24 volts TSH N.O. 120 volts Start P.B. N.C. (active high) (active low) Notice the difference.

O-0,1 Ladder Program I-0,0I-1,3 TSH Start P.B. Notice the difference. 24 volts TSH N.O. 120 volts Start P.B. N.C. (active high) 24 volts TSH N.O. 120 volts Start P.B. N.C. (active high) (active low) O-0,1 Ladder Program I-0,0I-1,3 TSH Start P.B.

“We-build-them” Programmable Controllers I-0,3O-0,3 WBT-4 I-1,3O-1,3 24 volts 120 volts 48 volts 24 volts TSH N.C. motor Starter To motor and FCE 120 volts Start P.B. N.C. O-0,1 Ladder Program I-0,0I-1,3 TSH Start P.B. (active high) (active Low) Self assessment tool Write the program for this input device configuration. Check your answer, if it doesn’t agree run this presentation again.