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

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CHAPTER 2: OVERVIEW OF PROGRAMMING Minimum and Maximum Values (Analog Points) All SNAP Ethernet-based I/O units with analog capability automatically keep track of minimum and maximum values on analog points. You can read these values at any time, for example, to record minimum and maximum temperatures. You can also reset min/max values. For example, if you want to record the maximum temperature at point 2 in each 24-hour period, you must reset the values after they are read each day. Offset and Gain (Analog Points) All SNAP Ethernet-based I/O units with analog capability can calculate offset and gain for analog input points. If a -50 mV to +50 mV input receives signals that are slightly off (not exactly -50 mV at the lowest point, for example), the offset and gain can be calculated so that values will appear accurately when read. Calculate offset first, and then calculate gain. The offset must be calculated at the point’s low scale, and the gain must be calculated at the point’s high scale. See the ioManager User’s Guide for instructions. NOTE: If you are using Modbus/TCP, you will need to calculate the offset and gain yourself. Then you can write offset and gain values to the brain. See the ioManager User’s Guide for more information. Clamping (Analog Points) SNAP Ethernet-based I/O units with analog capability can clamp values sent to analog output points so they do not go above or below a specific limit. For example, if you are using a 0–10 VDC output module, but the device attached to one of its points can only handle a maximum of 5 VDC, you can set an upper clamp of 5 VDC for that point. The values for upper and lower clamp are set in engineering units. Average Filter Weight (Analog Points) The I/O unit can use a filter weight to smooth analog input signals that are erratic or change suddenly. The formula used for filtering is Y = ( X - Y )/W + Y, where Y is the filtered value, X is 24 SNAP Ethernet-Based I/O Units Protocols and Programming Guide
CHAPTER 2: OVERVIEW OF PROGRAMMING the new unfiltered value, and W is the filter weight. The following graph shows the effect of filter weights (W) 2, 5, and 10 on a step input signal: 4 3 2 1 0 -1 -2 -3 -4 Y = (X-Y)/W + Y Filter Response for Different values of 'W' 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 A filter weight of zero turns off the calculation. Values less than or equal to 0.5 are changed to zero, since those values would cause an unstable signal. Set filter weight when configuring the analog point. SNAP Ethernet-Based I/O Units Protocols and Programming Guide 25 Input 2 5 10 As this graph shows, the larger the filter weight (W) you use, the smoother the analog signal.
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: 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 and 52: 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
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CHAPTER 3: USING THE SNAP ETHERNET
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GetLastStreamStandardBlock (ActiveX
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CHAPTER 4 Chapter 4 Using the IEEE
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CHAPTER 4: USING THE IEEE 1394-BASE
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Bytes 0-3 Bytes 4-7 Bytes 8-11 Byte
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Bytes 0-3 Bytes 4-7 Bytes 8-11 The
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Bytes 0-3 Bytes 4-7 Bytes 8-11 Byte
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Read and clear latches for individu
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Scaling CHAPTER 4: USING THE IEEE 1
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Read and Write Packet Structure Par
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CHAPTER 5 Chapter 5 Advanced Modbus
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CHAPTER 5: ADVANCED MODBUS PROGRAMM
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APPENDIX A Appendix A SNAP Ethernet
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Status Area Read—Read Only This i
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Date and Time Configuration—Read/
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Security Configuration—Read/Write
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Serial Module Configuration—Read/
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Wiegand Serial Module Configuration
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SNMP Configuration—Read/Write (Do
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Starting Address Length Type Descri
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Page 131 and 132:
Digital Point Read—Read Only NOTE
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Analog Point Read—Read Only See
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Analog and Digital Point Configurat
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Digital Events and Reactions—Read
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Analog Point Calculation and Set—
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Analog Read and Clear/Restart—Rea
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Serial Event Configuration—Read/W
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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
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O off-latch, 20 offset, 24 IEEE 139
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