Programming a Programmable Controller

1
Chapter 3

• Programming a Programmable Controller

2
Objectives

• Describe the available options for programming a
  PLC.
• Explain what online is in comparison to offline.
• List the advantages of software programming with
  a personal computer over a hand-held programming
  terminal.
• Explain the differences when interfacing a
  notebook personal computer to a PLC.
• Discuss open or soft PLC programming.
• Provide an overview of the IEC 1131-3 standard.

3
PLC Run Mode (1 of 2)

• The PLC can do nothing without someone developing
  a program and loading it into the PLC processors
  memory.
• Once the program has been loaded into PLC memory,
  the processor is put into run mode.
• While in run mode, the processor is solving the
  ladder program.

4
PLC Run Mode (2 of 2)

• While in run mode, the processor reads field
  device input signals and stores them in memory.
• There is one memory location for each input screw
  terminals ON or OFF state.
• Field device status information is stored in the
  input status table.

5
PLC Programming

• The oldest programming method is the hand-held
  programmer.
• Most popular programming method is IBM-compatible
  personal computer using either DOS or Windows
  software.
• Higher-end PLCs can only be programmed using
  software.

6
Allen-Bradley SLC 500 Programming Options
Image courtesy of Allen-Bradley, a Rockwell
Automation business
7
Allen-Bradley SLC 500 Hand-held Terminal (HHT)
Image courtesy of Allen-Bradley, a Rockwell
Automation business
8
Hand-held Programmer and SLC 500 Modular
Processors

• Hand-held are used only on fixed SLC 500, 5/01,
  and 5/02 processors.
• 5/03, 5/04, and 5/05 modular processors allow
  software programming only.
• MicroLogix 1000 PLC has own hand-held programmer.

9
Smart Hand-held Programming Terminal Advantages

• Compact size
• Easy to use and learn, no software required
• Low cost cheaper than notebook computer
• Easy to transport a program to the field
• Easy to transfer PLC program to HHT for editing
  or troubleshooting

10
Smart Hand-held Programming Terminal Disadvantages

• Holds one program at a time
• Newer more complex processors do not support
• Limited capability to display ladder rungs
• Documentation not displayed
• Many keystrokes needed to program or edit ladder
  program
• Dead battery means program lost

11
Software Programming Using PC Advantages

• Newer software Windows-based
• View or monitor multiple ladder rungs
• Documentation displayed
• Easy to scroll through rungs for troubleshooting
• Programs stored on computers hard drive
• Programs transferred to floppy or CD-ROM
• Easy editing and programming, drag and drop, cut
  and paste, etc.

12
Software Programming Disadvantages

• Maintenance personnel must learn Windows
  programming software.
• Notebook computers are expensive.
• Interface cards are expensive.
• Personal computers are not designed for factory
  use.
• There are frequent software upgrades.

13
Allen Bradley 1747-PIC Interface

• 1747-PIC communication box used to communicate
  from a PCs serial port to a SLC 500 family data
  highway 485 PLC
• Connects to any PC with a serial port
• Communicates with fixed SLC 500, and 5/01, 5/02,
  and 5/03 modular processors

14
AB 1747-PIC Interface Converter Interface
Image courtesy of Allen-Bradley, a Rockwell
Automation business
15
Connecting a GE RS-422/RS-485 to a RS-232 to a
PC (1 of 2)
Image courtesy of GE Fanuc Automation
16
Connecting a GE RS-422/RS-485 to a RS-232 to a
PC (2 of 2)

• Easy connection between personal computer and
  Series 90-30 or 90-70 PLC
• Connects to computer serial port
• Connects up to 50 feet away

17
Desktop or Industrial Computer Interface to PLC

• Allen Bradley 1784-KTX interface card
• PC ISA expansion slot card
• Connects to data highway plus or data highway 485
  processors
• Set up RSLinx software drivers to communicate

18
Allen-Bradleys 1784-KTX Interface Card
Image courtesy of Allen-Bradley, a Rockwell
Automation business
19
1784-KTX Card and Network Interface

• Easy network connectivity between personal
  computer and up to 64 data highway plus PLC 5 or
  SLC 5/04 processors (nodes) on DH network
• Up to 32 data highway-485 SLC 500 family
  processors on network

20
Node Addresses

• Each device on the network will require a unique
  identifier called a node or station address.
• Data highway plus network will support up to 64
  nodes, using octal addresses.
• Data highway-485 network will support up to 32
  nodes, using decimal addresses.

21
Communicating to Multiple SLC 500s
Image courtesy of Allen-Bradley, a Rockwell
Automation business
22
Notebook PC Interface to PLC

• Direct serial connection
• Hardware interface device such as 1747-PIC
• PCMCIA card

23
PCMCIA Interface Card

• Notebook PCs do not have expansion slots for
  installation of KTX card.
• PCMCIA card is a credit-card sized plug-in
  interface card.
• Allen-Bradleys PCMCIA card is called the 1784
  PCMK card.
• 1784 PCMK card serves as an interface between a
  PLC and a PC used as a programming terminal.

24
1784 PCMK Card Installation

• Interface between notebook PC and either DH or
  DH-485
• Interface PLC 5 or SLC 500 family processors
• Insert card into notebook computer PCMCIA slot

25
PCMK Card Insertion into a PCs PCMCIA Slot
Image courtesy of Allen-Bradley, a Rockwell
Automation business
26
Interface Cable Attachment to PCMK Card (1 of 2)
Image courtesy of Allen-Bradley, a Rockwell
Automation business
27
Interface Cable Attachment to PCMK Card (2 of 2)

• One cable to communicate to SLC 500, DH-485
  processors
• One cable to communicate to SLC 5/04,
  DHprocessor
• Same DH cable will communicate to PLC 5
  processors

28
Interface Cable from PCMK Card to PLC Processors
Image courtesy of Allen-Bradley, a Rockwell
Automation business
29
Industrial Computers

• Notebook and desktop personal computers were not
  designed for continuous use in the manufacturing
  environment.

30
Industrial Computers Are Designed to Withstand

• Dirt
• Shock
• Vibration
• High temperatures
• Wash downs

31
Industrial Computer Features

• Shock-mounted hard drives
• Air filters with air intake fans
• Hazardous environment rating
• NEMA 12, 4, and 4X ratings
• Integrated mouse on front panel
• Air-conditioned enclosure not required
• Modular for easy repair

32
Two Styles of Industrial Computers

• Panel-mount
• Computer and monitor built into one integrated
  unit
• Rack-mount
• Computer either separate component mounted in
  standard 19-inch rack or embedded inside
  enclosure
• Separate monitor or touchscreen display

33
Rockwell Automations RAC 6181 Computer
Connections
Image courtesy of Allen-Bradley, a Rockwell
Automation business
34
Connecting Industrial Mouse and Keyboard to the
RAC 6181
Image courtesy of Allen-Bradley, a Rockwell
Automation business
35
What Is the IEC 1131-3?

• Standardize PLC programming
• A program developed on one system could be used
  on other PLC platforms with minimum modification.
• Programming languages, Part 3 of the 1131-3
  standard, have attracted the most attention
  internationally.

36
IEC 1131-3 Programming Standard

• Defines a consistent set of programming languages
  for PLCs
• Ladder diagram
• Function block diagram
• Instruction list
• Structured text
• Sequential function block

37
Sequential Function Chart (1 of 2)

• It is similar to flowchart programming.
• It consists of steps and transitions.
• Each step is represented by a box that contains
  one or more major actions.
• When actions in the box are satisfied, the box is
  exited.
• Transition step must be true before next step.

38
Sequential Function Chart (2 of 2)
39
Sequential Function Chart OR Logic
40
Sequential Function Chart Illustrating a
Simultaneous Branch