snap ethernet-based i/o units protocols and programming guide

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CHAPTER 2: OVERVIEW OF PROGRAMMING For example, most digital bank data is in this form. To read the state of digital points, you would read the eight bytes starting at FFFFF0400000. Here’s how the data would be returned: At address: FFFFF0400000 FFFFF0400007 These bit numbers: 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 Show data for these points: 63 62 61 60 59 58 57 56 7 6 5 4 3 2 1 0 On modules in these positions in the rack: 15 14 1 0 Therefore, at this address: FFFFF0400000 This hex data: B 1 Equals this binary data: 1 0 1 1 0 0 0 1 Showing the states: On Off On On Off Off Off On Of these points: 63 62 61 60 59 58 57 56 Data from other addresses marked as masks is formatted in a similar way. Unsigned 32-bit Integer Data Much of the data in the memory map is in the form of unsigned integers, either one byte, two bytes, or four bytes. With multiple bytes, since the brain uses a Big Endian architecture, the high order byte is in the low order address. For example, digital bank counter data is in 4-byte unsigned integers. It takes four bytes to contain the data for one point. To read digital bank counter data for point 0, you would start with address FFFFF0400100. The following table shows the pattern of bank counter data for the first few points: Bytes at these addresses: Show data for this point: On the module in this position on the rack: FFFFF0400100 FFFFF0400101 FFFFF0400102 FFFFF0400103 FFFFF0400104 FFFFF0400105 FFFFF0400106 FFFFF0400107 FFFFF0400108 FFFFF0400109 FFFFF040010A FFFFF040010B FFFFF040010C FFFFF040010D FFFFF040010E FFFFF040010F The most significant byte is at the lowest address. For point 0, for example, you might receive the following data: 42 SNAP Ethernet-Based I/O Units Protocols and Programming Guide FFFFF0400110 FFFFF0400111 FFFFF0400112 FFFFF0400113 FFFFF0400114 FFFFF0400115 FFFFF0400116 FFFFF0400117 0 1 2 3 4 5 0 1 At this address This binary data Equals this hex data 16 BB 18 87 FFFF F040 0100 0001 0110 16 FFFF F040 0101 1011 1011 BB FFFF F040 0102 0001 1000 18 FFFF F040 0103 1000 0111 87
CHAPTER 2: OVERVIEW OF PROGRAMMING The 32-bit integer for this reading would be 16 BB 18 87 (most significant byte at lowest address). This hex figure correlates to the decimal value 381,360,263. Remember that if you are processing this data using a Little Endian computer (such as an Intel ® -based PC), you must convert the data from the Big Endian format in order to use it. Little Endian format is the opposite of Big Endian; Little Endian places the most significant byte at the highest address. Digital Point Data For consistency in starting addresses, data for individual digital points has a length of four bytes. However, only the least significant bit contains the data you’re looking for. For example, to read the state of point 0, you would start with address FFFFF0800000. Data would be returned as follows: To read this information: Point 0: Point State Use these addresses: FFFFF0800000 FFFFF0800001 FFFFF0800002 FFFFF0800003 These bits: 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 Contain this data (binary): 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 (hex): 0 0 0 0 0 0 0 1 IEEE Float Data For individual analog points, values, counts, and minimum and maximum values for one point are located next to each other in the memory map. All are four bytes and are IEEE 754 floats. For example, individual analog point data for points 0 and 1 appears in these addresses: Beginning Address Ending Address Module Point Data FFFF F0A0 0000 FFFF F0A0 0003 Scaled units FFFF F0A0 0004 FFFF F0A0 0008 FFFF F0A0 0007 FFFF F0A0 000B 0 Counts Minimum value (E.U.*) FFFF F0A0 000C FFFF F0A0 0040 FFFF F0A0 000F FFFF F0A0 0043 0 Maximum value (E.U.*) Scaled units FFFF F0A0 0044 FFFF F0A0 0048 FFFF F0A0 0047 FFFF F0A0 004B 1 Counts Minimum value (E.U.*) FFFF F0A0 004C * Engineering Units. FFFF F0A0 004F Maximum value (E.U.*) IEEE 754 float format is as follows: 1 bit 8 bits 23 bits x xxxxxxxx xxxxxxxxxxxxxxxxxxxxxxx Sign Exponent Significand Ignore these bits. Point state is ON. SNAP Ethernet-Based I/O Units Protocols and Programming Guide 43
Page 1 and 2: SNAP ETHERNET-BASED I/O UNITS PROTO
Page 3 and 4: Table of Contents Chapter 1: Introd
Page 5 and 6: Non-velocity Algorithms............
Page 7 and 8: Disconnecting......................
Page 9 and 10: Data Logging Configuration—Read/W
Page 11 and 12: Chapter 1 Introduction CHAPTER 1 We
Page 13 and 14: About this Guide CHAPTER 1: INTRODU
Page 15 and 16: For Help CHAPTER 1: INTRODUCTION If
Page 17 and 18: FEATURE CHAPTER 1: INTRODUCTION Ema
Page 19 and 20: CHAPTER 1: INTRODUCTION This task C
Page 21 and 22: CHAPTER 2 Chapter 2 Overview of Pro
Page 23 and 24: Referencing SNAP I/O Points CHAPTER
Page 25 and 26: Analog and Digital Systems (N Brain
Page 27 and 28: Digital-Only Systems The following
Page 29 and 30: I/O Point Types CHAPTER 2: OVERVIEW
Page 31 and 32: CHAPTER 2: OVERVIEW OF PROGRAMMING
Page 33 and 34: Watchdog (Digital and Analog Points
Page 45 and 46: Streaming Data CHAPTER 2: OVERVIEW
Page 47 and 48: Logging Data Area Number of Bytes I
Page 49 and 50: Using PID Loops What is a PID? CHAP
Page 51: Equations Common to All Algorithms
Page 55 and 56: CHAPTER 3 Chapter 3 Using the SNAP
Page 57 and 58: CHAPTER 3: USING THE SNAP ETHERNET
Page 63 and 64: Environment Visual Basic 6 Internet
Page 65 and 66: MemMap Example Code CHAPTER 3: USIN
Page 71 and 72: Return Values CHAPTER 3: USING THE
Page 73 and 74: IsOpenDone V Close V Return Values
Page 75 and 76: Digital Point Methods CHAPTER 3: US
Page 77 and 78: SetDigBankOnMask V [in] long nPts63
Page 79 and 80: Analog Bank Methods CHAPTER 3: USIN
Page 81 and 82: GetStatusWatchdogTime [out] long pn
Page 87 and 88: GetLastStreamStandardBlock (ActiveX
Page 89 and 90: CHAPTER 4 Chapter 4 Using the IEEE
Page 91 and 92: CHAPTER 4: USING THE IEEE 1394-BASE
Page 93 and 94: Bytes 0-3 Bytes 4-7 Bytes 8-11 Byte
Page 95 and 96: Bytes 0-3 Bytes 4-7 Bytes 8-11 The
Page 97 and 98: Bytes 0-3 Bytes 4-7 Bytes 8-11 Byte
Page 99 and 100: Read and clear latches for individu
Page 101 and 102: Scaling CHAPTER 4: USING THE IEEE 1
Page 103 and 104:
Read and Write Packet Structure Par
Page 105 and 106:
CHAPTER 4: USING THE IEEE 1394-BASE
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CHAPTER 4: USING THE IEEE 1394-BASE
Page 109 and 110:
CHAPTER 5 Chapter 5 Advanced Modbus
Page 111 and 112:
CHAPTER 5: ADVANCED MODBUS PROGRAMM
Page 113 and 114:
APPENDIX A Appendix A SNAP Ethernet
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Status Area Read—Read Only This i
Page 117 and 118:
Date and Time Configuration—Read/
Page 119 and 120:
Security Configuration—Read/Write
Page 121 and 122:
Serial Module Configuration—Read/
Page 123 and 124:
Wiegand Serial Module Configuration
Page 125 and 126:
SNMP Configuration—Read/Write (Do
Page 127 and 128:
Starting Address Length Type Descri
Page 129 and 130:
Page 131 and 132:
Digital Point Read—Read Only NOTE
Page 133 and 134:
Analog Point Read—Read Only See
Page 135 and 136:
Analog and Digital Point Configurat
Page 137 and 138:
Digital Events and Reactions—Read
Page 139 and 140:
Page 141 and 142:
Analog Point Calculation and Set—
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Analog Read and Clear/Restart—Rea
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Page 147 and 148:
Page 149 and 150:
Serial Event Configuration—Read/W
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Page 155 and 156:
Page 157 and 158:
Data Log—Read/Write (Does not app
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Appendix B Table of Offsets Introdu
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Module Point (Decimal) Point (Hex)
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Index A access, setting up SNMP sec
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error codes IEEE 1394-based protoco
Page 167 and 168:
O off-latch, 20 offset, 24 IEEE 139
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