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 MSB LSB 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) 0111000111111000 0111000111111000 Double Word Sign bit Lower 31 bits contain the value 32 – bit signed integer data range: -2,147,483,648 to +2,147,483,647

29. 32-bit Signed Integer (2 of 2) 0111000111111000 0111000111111000 Double Word Word Byte

30. Basic PLC Data Types Data TypeDescriptionSizeRange BoolSingle bitBit1 = ON 0 = OFF Sint8 bitsByte-128 to +127 Int16 bitsWord-32,768 to +32,767 Dint32 bitsDouble Word -2,147,483,648 +2,147,483,647 RealFloating pointReal or floating Point Larger than Dint or with Decimal point

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 Channel 0 Channel 1 0111110101011111 0000001111111000 0000000000000000 1001111111000000 Channel 2 Channel 3 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

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

51. Input Channel Configuration Word

53. What value will you enter into the move instruction’s source?

54. Understanding Binary Coded Decimal (BCD)

55. Single-digit BCD Thumb-wheel Interfaced to a PLC

56. Binary Coded Decimal Number Bit Patterns

57. Binary Coded Decimal

58. Two-digit BCD Thumb-wheel Interface

59. Four-digit BCD Thumb-wheel

60. Output Module Connected to Seven-segment Display

61. Comparison of BCD to Decimal and Binary Numbers

62. BCD Invalid Codes

63. Decimal, Hexadecimal, and BCD Comparisons

64. SLC 500 Conversion from BCD

65. SLC 500 Converting to BCD

66. PLC 5 Converting from BCD

67. PLC 5 Converting to BCD