PROGRAMMABLE LOGIC CONTROLLERS 5TH EDITION PETRUZELLA SOLUTIONS MANUAL

1. To accept signals from the machine or process devices and to convert them into signals that can be used by the controller 2. To convert controller signals into external signals that are used to control the machine or process 3. a) A rack that is located away from the processor module near the field devices b) To minimize the amount of wiring required 4. By its address 5. Type refers to an input or output Slot refers to the physical location of the I/O module Word and bit refers to the actual module terminal connection 6. Bit level addressing specifies a discrete device that is connected to a specific terminal. Word level addressing specifies an analog device connected to a module that uses a word of information. 7. In tag-based addressing you use a tag (alphanumeric name) to address data (variables). In rack/slot-based addressing a fixed numeric format is used to identify the address data. 8. An input/output PC interface card 9. Combination I/O modules 10. Connections for the power supply 11. For ease of wiring and replacing modules 12. The advantage with the high-density module is that it is possible to install up to 64 inputs or outputs in one slot for greater space savings. The disadvantage is that the high-density output modules cannot handle as much current per output. 13. ON/OFF devices such as selector switches, pushbuttons and limit switches 14. ON/OFF devices such as lights, solenoids and motor starters 15. The backplane supplies current and voltage for the modules from the power supply 16. An optical isolator is used to provide electrical isolation between the field wiring and the PLC backplane internal circuitry.  17. Power and Logic sections 18. Senses when a signal is received Converts the input signal to the correct voltage level Isolates the PLC from the input voltage or current Sends a signal to the processor indicating which sensor originated the signal 19. Triac 20. a) 1 amp per point b) A control relay is connected to the output module. The contacts of the control relay are then used to control the larger load. 21. Transistor 22. A discrete relay-type module uses an electromechanical relay element for switching which allow it to work for AC or DC applications. 23. a) Sinking and sourcing are terms used to describe a current signal flow relationship between field input and output devices in a control system and their power supply. b) Sourcing 24. Discrete I/O modules allow only ON/OFF devices to be connected. Analog I/O modules allow analog or varying voltage or current devices to be connected. 25. Used to convert analog signals to an equivalent digital value 26. Used to convert digital signals to an equivalent analog value 27. Voltage sensing and current sensing 28. Temperature, speed, level, flow, weight, pressure, and position 29. A twisted shielded pair cable is used in wiring the circuit to reduce unwanted electrical noise signals that can be induced in the conductors from other wiring 30. Unipolar modules can accept an input signal that varies in the positive direction only. Bipolar signals swing between a maximum negative value and a maximum positive value. 31. The analog input channel is capable of sensing voltages down to 0.3V increments. 32. The loop power may be supplied by the sensor or may be provided by the analog output module 33. Control valves, chart recorder, electronic drives 34. a) Used to count pulses such as motor encoders that occur at very high speeds b) Allows the use of thumbwheel switches for feeding information to a PLC c) Allows the transmitting and receiving of TTL signals for communication with the PLC’s processor d) Used to monitor the output of incremental or absolute encoders e) Allows the transmitting and receiving of ASCII files f) Provides pulse trains to a stepper-motor translator, which enables control of a stepper motor g) Enables a PLC to operate devices that require BCD-coded signals 35. a) Used to maintain a process variable such as temperature, flow, level, or speed within set limits of a specified set point. b) Used in applications involving accurate high-speed machining and packaging operations c) Used to establish point-to-pint connections with other intelligent devices for the