Chapter 4 - Programming Terminals

Question 1

Dedicated Programming and Display Terminals?

Answer 1

• Used primarily to enter programs and monitor PLC’s
• Built on Windows Platforms
• Consists of: CRT or LCD, keypad, electronic circuitry for creating programs and changing the monitoring terminal
• Display terminals have extensive alarm capabilities
• Can be microprocessor based with memory and software for uploading, downloading and altering programs.
• Can be as small as a palm-pilot

Question 2

Hand-Held Programmers?

Answer 2

• Inexpensive and portable means of programming small PLC’s
• The size of a calculator, has LED or LCD displays, a keyboard with numeric keys, programming instruction keys and special function keys
• Suited for installations with constant circuit changes or accessing remote PLC’s not networked
• Newer ones have microprocessors capable of system diagnostics and message display and wifi connection

Question 3

Computer Based Programming Terminals and Software?

Answer 3

• Capable of ancillary activities (word processing etc.)
• Massive memory capacity/ scalable to add more I/O points
• Faster than dedicated terminals, can execute 1000 lines of logic in 1 ms
• Can use custom commands in C, Visual Basic and ActiveX with softlogix software
• Can use programming software to create contacts and coils and special mnemonic functions

Question 4

Downloading and Uploading?

Answer 4

When a programmable terminal transfers a program into a PLC its called downloading. When the program is retrieved its called uploading.

Question 5

Types of Programming Software?

Answer 5

• Documentation: customizing coils and contacts and adding comments to logic layer
• Data collection and analysis: based on spreadsheet format. Collects data from single or multiple PLC CPU’s.
• Real Time Operator: allows supervisory control to be established to advise the operator on process conditions and failure warnings.
• Simulation: Used to simulate the operation of a process control program before designing the PLC system

Question 6

Host-Computer Based Systems?

Answer 6

Centralized control: multi-user system centrally located in a facility that controls I/O connections, PLC’s and motion control.
Distributed control systems (DCS): PLC’s are interconnected to transfer data between one another by a small communications cable, considered more fail-safe.
Supervisory, Control and Data Acquisition System (SCADA): A system that performs both monitoring and control of a process or facility

Question 7

Baud Rate?

Answer 7

The transmission speed of binary data measured in bits per second.

Question 8

Peripheral Devices?

Answer 8

Devices connected to PLC’s that are not essential to their function.

• Programming Terminals
• Printers
• Thumbwheel switches
• USB, Removable Storage, Compact Flash Memory