Copyright Goodheart-Willcox Co., Inc. Chapter 9 PLC Counter Instructions 203 L AB ACTIVIT Y 9A PLC Counter Instructions This lab activity can be found in the Lab Manual as Lab Activity 9-1. Objective In this activity, you will use counter instructions to create PLC ladder logic diagrams. Then, you will verify the operation of the PLC ladder logic diagrams on your PLC lab station. Equipment • Allen-Bradley SLC 500 series PLC trainer • Single-pole, single-throw (SPST) switch • Normally open pushbuttons (2) • Red, green, and white pilot lights Procedure Activity 1 In this activity, you will create a PLC ladder logic diagram that carries out the following operations. • A fan is to be turned on when counter zero (C5:0) counts down from 7 to 0 and when either counter one (C5:1) goes up to 14 or counter two (C5:2) counts down from 14 to 0. • One switch resets the entire process. Step 1. Draw the relay logic diagram for this circuit. Step 2. Assign PLC input/output ports to the devices. Then, complete the PLC I/O connections on your PLC lab station. Step 3. Use the Rockwell RSLogix 500 software to create the PLC ladder logic diagram. Step 4. Download the PLC ladder logic diagram into the PLC station. Place the PLC in the run/monitor mode. Step 5. Demonstrate your working PLC system for your instructor. Activity 2 In this activity, you will create a PLC ladder logic diagram that uses counters and retentive timer ON-delay instructions to carry out the following operations. • If the red pushbutton (PBR) is pressed six times, the red pilot light (Red_ PLT) turns on. • If the green pushbutton (PBG) is pressed three times, the green pilot light (Green_PLT) turns on.