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Published byGabriella Weaver Modified over 9 years ago
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Modbus to DNP3 Protocol Converter Group 24: Joshua Daly, CpE Daniel Doherty, CpE Mac Lightbourn, EE Joseph Wilkinson, EE
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Controllers like this one alternate which pumps in the lift station are active to maintain the desired flow rate and water level. Other functions include ventilation control and alarms for high water or odor levels. Many controllers are networked together and there is no industry-standard network protocol.
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Modbus vs. DNP3 Project motivation: MPE needs to allow for communication between network nodes that are using these different protocols. CreatedMarket Difficulty of Implementation Equipment Costs Open Standard? Records time- stamped event sequences? Efficiency (bytes transferred for a given bandwidth) Modbus 1979 Widely used in all SCADA industries Low$100+NoWith DifficultyAverage DNP3 1993 Sometimes used in water/ wastewater applications High $500- $3000 Yes Very High
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Four-Semester Plan Device Build User Interface Initialization Phase II Network Communications Security Phase I
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Key Specs Operates between -10 and 80 degrees Celsius Protects against surges of 120 V MCU clock has a backup battery that can power the MCU for 12 hours if power is lost Sends alarm to master device when power is lost Takes Ethernet input and gives Ethernet output Allows user to view and change networking parameters Logs 20,000 events, even when power is lost, with 98% fidelity Records date and time of each event to millisecond accuracy Notifies master device of all events with 95% fidelity
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Four-Layer PCB Design
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Choosing an MCU Microchip PIC32 TI Stellaris ARM Cortex M3 Freescale MC9S12NE64 Freescale MC9S12XDP512 Price/unit (bulk purchases)$1.58+$1.00+$6.93+$13.07+ Pins28, 36, or 4464, 100, 144, or 15680 or 11280, 112, or 144 Processor Speed80 MHz 16 MHz80 MHz Memory128 KB SRAM 256 KB SRAM, 32 KB Flash 64 KB Flash, 8 K RAM 512 KB Flash, 64 KB SRAM Special Considerations Cheap/free dev tools; extensive application notes Ethernet-ready Ethernet-ready with application notes; already widely used by the sponsor XGate coprocessor module; Non- multiplexed external bus interface; in same family as MCUs used by our sponsor
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Ethernet Integration Ethernet jacks include integrated magnetic isolation modules Input and output both feature a dedicated Ethernet controller Modbus input and DNP3 output interface with the MCU via SPI ports for high speed communications
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ENC28J60 J00-0045NL
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Noise Due to SPI Lines
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To reduce the noise, we took three measures 1. We placed pull-up resistors close to the microcontroller 2. We used large-value resistors for the pull-ups and large-value bypass capacitors 3. We isolated the MOSI and MISO lines with copper ground
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Push Buttons and LEDs
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Coding Environments Visual Studio Used while PCB board was in development Familiar environment Code Warrior Freescale MCU Optimization of.s19 file
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Firmware Overview Creation of data Structs to maintain parameters Menu system Allows user to adjust stored parameters Strict requirements from the sponsor Initialize all components on the PCB Handle all button functionality
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Firmware Challenges Project requirements changed midway through Integration of all parts on PCB Delayed action based on buttons Code must be well documented and easily modified
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Data Storage Stored in contiguous blocks Storage requirements Factory defined User defined
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Buttons Required Guidelines Button Functionality Menu Navigation Time Delayed press
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Screen Display Screen 3 7-segement displays Mimic the current display used by MPE Allows user to visually navigate and set parameters
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Power Subsystem
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Power Supply Requirements Takes in 24 V DC This supply is shared with other components in the lift station control panel This is a low voltage in comparison to other devices being used in industrial applications The low voltage bypasses some of the testing requirements for meeting UL standards
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Power Supply Requirements Surge Protection Must handle currents up to 80 A Must correct irregular voltages Multiple devices are connected in a shunt configuration for combined benefits
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Power Supply Requirements Type of DeviceLifetime-number of surges Response Time Transient Voltage Suppression Diode -1 ps Metal Oxide Varistor1000 surges1 ns Zener Diodeinfinite1 us Gas discharge tube20 surges5 us
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Input Surge Protection
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Power Supply Requirements Must be fed through a DIN rail mount All devices in the lift station control panel attach to one rail Mount also serves as chassis ground for added surge protection
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DC/DC Converter Voltage is stepped down to 3.3 V and then fed to the power plane To conserve power, a passive switching regulator was chosen Our configuration is a common circuit with extensive application notes
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Financials ComponentPriceQuantityTotal Clock$2.344$9.36 Clock-Back Battery$4.281 Microcontroller$22.851 Switching Regulator$3.751 Schottky Diode$0.551 TVS Diode$0.731 Inductor$3.561 LCD Driver$1.751 3-Digit 7-Segment Display $2.911 Ethernet Controller$5.832$11.66 Ethernet Connector$4.732$9.46 Super-Red LED$1.082$2.16 Cyclone Pro Programmer $298.801 Metal Oxide Varistor$0.561 Din Rail Connector$1.541 CaseDonated1 PCB$80.001 Pin Connector$0.153$0.45 Resistor$0.0217$0.34 Capacitor$0.1220$2.40 Total $457.11
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