PLC Test for CH. 1

What is the memory capacity, expressed in bits, for a PLC that uses 16-bit words and has a 8 K word capacity?

131,072

What are the two most common type of PLC programming devices?

A PC and a portable Programming Device

What is a PLC?

An industrial grade computer that is capable of being programmed to perform control functions.

State two ways in which I/O is incorporated into the PLC.

Fixed and Modular

Explain the difference between open and proprietary PLC architecture.

Open means that one manufacture's components will work with another manufacture's components, while proprietary is a little stricter.

List six distinct advantages that PLCs offer over conventional relay-based control systems.

Reliability, flexibility, lower cost, communications capability, faster response time, and it is easier to troubleshoot.

Identify four tasks in addition to relay switching operations that PLCs are capable or performing.

Timing, Counting, Calculating and Comparing

The programmable controller operates in real time. What does this mean?

You get the information when it happens.

Explain the main function of each of the following major components. a.) CPU b.) I/O c.) Programming device d.) Power Supply

a. Processes Information b.Your input and output module used for making contact. c.What you use to tell the system what to do. d.Supplies power to the PLC.

Compare the PLC and PC with regard to: a.) Physical hardware differences b.) Operating environment c.) Method of programming d.) Execution of program

a.) In PLC there are really only 3 important hardware components: CPU, power supply, and I/O modules. In a PC there are a few more. b.) PCs are meant for temp. controlled rooms and personal use. PLCs are meant for an industrial environment and excessive temps. c.) PLCs use ladder logic, PCs use a more complex method. d.) PCs can run several program and several action. PLCs run one program in a nice, sequential order.

List four criteria by which PLCs are categorized.

functionality, number of inputs and outputs, cost, and physical size

Explain the terms program an programming-language as they apply to a PLC.

program- a series of instructions; programming language- relay ladder logic, based on electromagnetic relay control.

What is the standard programming language used with PLCs?

relay ladder logic

Compare the single-ended, multitask, and control management types of PLC applications.

• A single ended application involves one PLC controlling one process. • A multitask PLC application involves one PLC controlling several processes. • A control management PLC application involves one PLC controlling several others.

List five factors affecting the memory size needed for a particular PLC installation.

• Number of I/O points used • Size of control program • Data-collecting requirements • Supervisory functions required • Future expansion

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What two categories of software written and run on PCs are used in conjunction with PLCs?

• PLC software that allows the user to program and document gives the user the tools to write a PLC program—using ladder logic or another programming language—and document or explain the program in as much detail as is necessary. • PLC software that allows the user to monitor and control the process is also called a human machine interface (HMI).

What is a programmable automation controller (PAC)?

Combines PLC ruggedness with PC functionality. Using PACs, you can build advanced systems incorporating software capabilities such as advanced control, communication, data logging, and signal processing with rugged hardware performing logic, motion, process control, and vision.

Compare the method by which the process control operation is changed in a relay-based system to the method used for a PLC-based system.

In a relay-based all the components are hardwired together and operate how you wire it to operate. In a PLC-based system all the components are hardwired to the I/O modules and operate according to how it is programmed to operate.

Describe how the I/O modules connect to the processor in a modular-type PLC configuration.

They both have contact to the back-pane.

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What does the instruction set for a particular PLC refer to?

The type of instructions supported.