1 / 67

Storing and Organizing Data

Storing and Organizing Data. Why Do I Need to Understand How Data Is Represented?. In order to install, program,maintain, and troubleshoot today’s PLCs, you must understand the different methods by which internal data is represented. Objectives.

dabbs
Download Presentation

Storing and Organizing Data

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Storing and Organizing Data

  2. Why Do I Need to Understand How Data Is Represented? • In order to install, program,maintain, and troubleshoot today’s PLCs, you must understand the different methods by which internal data is represented.

  3. Objectives • Identify the commonly used number systems used in PLCs. • Convert binary data to decimal. • Examine how data is stored in PLC data tables. • Describe how BCD field devices interface.

  4. PLC Words • One measure of a computer’s capabilities is the length of the data words on which it can operate. • Many current PLCs use 16-bit words. • Many newer PLCs use 32-bit words. • SLC 500 and PLC 5 family PLCs are 16-bit computers. • Control Logix is a 32-bit computer.

  5. Number Systems Typically Used with PLCs

  6. We Use Words to Represent Information • Our words are groups of characters grouped together to represent something. • The words we use are of different lengths. • Controller • The • Monday

  7. We Use Symbols Called Numbers to Represent Data • Everyday numbers are decimal. 12,345

  8. Computers Do Not Understand • Computers do not understand the words and numbers humans use. • Computers have their own language called binary.

  9. Binary Concept • Two-state devices are described as either discrete or digital devices. • Discrete or digital devices are simply either on or off. • Binary is based on two states, on or off.

  10. Binary Language • Binary information is also represented in groups of characters. • A group of binary digits called bits can be organized into words. • Binary bits consist of only two characters • 1 and 0

  11. Binary Words • 16 bits grouped together is called a word. • A binary word might look like: 1010 1010 1010 1010 1010

  12. Information Represented as Combinations of Bits

  13. Decimal Numbers • Ten digits • 0,1,2,3,4,5,6,7,8,9 • Base or radix • 10 • Weights • 1, 10, 100, 1000

  14. Decimal Number System

  15. The Binary Number System Has the Following Characteristics • Two digits • 0 or 1 • Base or radix • 2 • Weights • 1, 2, 4, 8, 16, 32, 64…

  16. 16-bit Binary Word Bit Weighting MSBLSB • LSB = least significant bit • MSB = most significant bit

  17. Binary Numbers Place Values

  18. Binary Number Weighting

  19. Decimal 0 through 7 Represented with Binary Bits

  20. Comparison of Decimal to Binary Numbers

  21. Parts of a 16-bit Word

  22. Bytes, Nibbles, and Bits

  23. PLC Data Formats • Two 8-bit unsigned bytes of data • 16-bit unsigned integer • 16-bit signed integer • 32-bit signed integer • Binary coded decimal • Hexadecimal

  24. Two 8-bit Unsigned Bytes of Data

  25. Hexadecimal

  26. 16-bit Signed Integer

  27. 16-bit Unsigned Integer

  28. 32-bit Signed Integer (1 of 2) Double Word Lower 31 bits contain the value Sign bit 32 – bit signed integer data range: -2,147,483,648 to +2,147,483,647

  29. 32-bit Signed Integer (2 of 2) DoubleWord Byte Byte Byte Byte Word Word

  30. Basic PLC Data Types

  31. Data Table Format • Words are 16 bits. • Bits 0 through bit 15 • First word or bit is always 0. • SLC 500 data tables can contain up to 256 words (0 to 255). • PLC 5 data tables can contain up to 1,000 words (0 to 999).

  32. Words Arranged in a Data Table

  33. Status Table Words Assigned by Module Requirements • The number of status table words assigned depend on what a specific module needs. • 16-point module equals 16 bits. • 32-point module equals 32 bits. • Four-channel analog equals four words. • Eight-channel analog needs eight.

  34. SLC 500 I/O Configuration

  35. 16-point Module’s I/O Points Represented in a Word

  36. Physical Input Conditions and the Corresponding Input Data Word

  37. 8-Point Input Module Represented in a Word

  38. SLC 500 Input Status Table

  39. 24-point I/O Module Represented in Two Words

  40. Two Words Representing Inputs for a 32-bit Module

  41. Output Status File Correlation to Module

  42. SLC 500 Digital Outputs

  43. Four Words Representing a Four-channel Analog Module 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Channel 0 Channel 1 Channel 2 Channel 3

  44. SLC 500 Analog Input Channels

  45. SLC 500 Output Analog Channels

  46. So, What’s in It for ME?? • I need to be able to work with different number systems. • PLC configuration • PLC troubleshooting • Program interpretation • Error code interpretation • Data conversion to different hardware

  47. SLC 500 Analog Input Module Configuration • You need to configure a 1747sc-INI4i analog input module. • Module configuration specifications are listed below.

  48. Channel Configuration Word Channel Data Word SLC 500 Processor Analog Input Module Channel Status Word Analog Input Signal Channel Configuration

  49. Specifications • Enable the input channel • 4- to 20-mA input range • Work in engineering units • Pump to run maximum if open input • 60-Hz input filter • Auto calibration disabled

  50. What Do You Need to Do? • Determine the 16-bit data word for the configuration. • Convert the binary word into decimal. • Program a move instruction on your SLC 500 ladder to move the configuration data to each analog channel.

More Related