1. What operations are performed by the processor during the program scan? 2. With a ControlLogix processor, I/O updates occur asynchronously. Explain what this means. 3. In ladder logic programming into what two broad categories can instruction types be classified? 4. A field input switch is examined using an XIC instruction. a. What is the value (0 or 1) stored in its memory bit when the switch is opened and closed? b. What is the state of the instruction (true or false) when the switch is opened and closed? 5. A field input switch is examined using an XIO instruction. a. What is the value (0 or 1) stored in its memory bit when the switch is opened and closed? b. What is the state of the instruction (true or false) when the switch is opened and closed? PART 2 PROBLEMS 356 Part 2 Bit-Level Programming 6. The value of an OTE instruction as it appears in the Monitor Tags window is 1. Explain what this means as far as the status of a real-world field output and programmed XIC and XIO instructions associated with this tag are concerned. 7. Define a tag in the ControlLogix system. 8. What advantage do tag-based addressing systems have over rack/slot types? 9. How is an internal relay programmed in the ControlLogix system? 10. The output latch instruction is a retentive output instruction. Explain what retentive means. 11. The ControlLogix ONS instruction is a one-shot instruction. Explain what this means. PART 2 REVIEW QUESTIONS 1. Modify the original ControlLogix start/stop motor control program (Figure 15-34) with a second start and stop button added to the program. The additional start button is to be connected to pin 1 and the stop button to pin 2 of the digital input module. 2. Extend control of the original ControlLogix internal relay program (Figure 15-38) used to control a room light from 3 entrances to 4. The additional singlepole switch is to be connected to pin 4 of the digital input module. 3. Implement the hardwired latching relay alarm circuit of Figure 15-47 in Logix format. The alarm will be latched on anytime: • The normally open temperature switch closes. • Both normally open float switches 1 and 2 close. • Either normally open sensor switch 1 or 2 closes while the normally closed pressure switch is closed. 4. Implement the hardwired tank filling and emptying operation shown in Figure 15-48 in Logix format. 120 VAC Relay contact Latch coil Temp Sw Float Sw 1 Sensor Sw 1 Sensor Sw 2 Reset button 24 VDC Float Sw 2 Pressure Sw Alarm L Unlatch coil U Figure 15-47 Hardwired latching relay alarm circuit for Problem 3.
Petruzella_ProgrammableLogicControllers__5e
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