310203fB Intro To PLC's Part B

Question 1

When using a PC to program a PLC, which four folders are typically part of the system file? What information do they store?

Answer 1

1. Tag database - stores information on all variables
2. Program - stores the user program
3. Communication - stores information on how to connect to the PLC processor
4. Configuration - stores information on the modules that make up the PLC

Question 2

_______ tags refer to memory locations defined by another existing tag

Answer 2

Alias tags refer to memory locations defined by another existing tag

Question 3

________ tags are accessible to any program within the controller

Answer 3

Global tags are accessible to any program within the controller

Question 4

What occurs when uploading and downloading PLC programming with a PC?

Answer 4

Uploading is the process of taking the PLC’s current programming and writing it to the PC
Downloading is the process of taking a program that exists on a PC and writing it to the PLC’s processor memory

Question 5

Name three graphic PLC programming languages

Answer 5

1. Ladder diagrams (LD)
2. Function block diagrams (FBD)
3. Sequential functions chart (FSC)

Question 6

Name two text-based PLC programming languages

Answer 6

1. Structured text (ST)
2. Instruction list (IL)

Question 7

Typically the source of a PLC fault can be narrowed down to which four areas?

Answer 7

1. Processor
2. Input module
3. Output module
4. Programming

Question 8

Typically a major PLC fault causes the processor to go into fault mode where it does which three things?

Answer 8

1. Turns on the appropriate status lights
2. De-energizes all its outputs or freezes them in their present state
3. Saves a fault code to memory

Question 9

List the five steps that are involved in a systematic approach to troubleshooting

Answer 9

1. Identify the problem
2. Isolate the cause
3. Correct the problem
4. Verify the correction
5. Document the problem and the solution