Modbus to DNP3 Protocol Converter
description
Transcript of Modbus to DNP3 Protocol Converter
Modbus to DNP3 Protocol Converter
Group 24: Joshua Daly, CpE Daniel Doherty, CpE Mac Lightbourn , EEJoseph Wilkinson, EE
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.
Modbus vs. DNP3
Project motivation: MPE needs to allow for communication between network nodes that are using these different protocols.
Created Market 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+ No With Difficulty Average
DNP3 1993
Sometimes used in water/
wastewater applications High $500-
$3000 Yes Yes Very High
Four-Semester Plan
Device BuildUser InterfaceInitialization
Phase IINetwork CommunicationsSecurity
Phase I
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
Four-Layer PCB Design
Choosing an MCU
Microchip PIC32TI Stellaris ARM
Cortex M3Freescale
MC9S12NE64Freescale
MC9S12XDP512Price/unit
(bulk purchases) $1.58+ $1.00+ $6.93+ $13.07+
Pins 28, 36, or 44 64, 100, 144, or 156 80 or 112 80, 112, or 144
Processor Speed 80 MHz 80 MHz 16 MHz 80 MHz
Memory 128 KB SRAM256 KB SRAM, 32
KB Flash64 KB Flash, 8 K
RAM512 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
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
ENC28J60 J00-0045NL
Noise Due to SPI Lines
MOSI and MISO signals transmit at frequencies of 10-100 MHz
Rapid logic transitions on these signals combined with the effective series inductance of the traces lead to a field effect
The result is noise
Noise Due to SPI Lines
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
Push Buttons and LEDs
Coding Environments
Visual Studio Used while PCB board was in
development Familiar environment
Code Warrior Freescale MCU Optimization of .s19 file
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
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
Data Storage
Stored in contiguous blocks
Storage requirements Factory defined User defined
Buttons
Required Guidelines
Button Functionality
Menu Navigation
Time Delayed press
Screen
Display Screen 3 7-segement displays
Mimic the current display used by MPE
Allows user to visually navigate and set parameters
Power Subsystem
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
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
Power Supply Requirements
Type of Device Lifetime-number ofsurges
Response Time
Transient Voltage Suppression Diode
- 1 ps
Metal Oxide Varistor 1000 surges 1 ns
Zener Diode infinite 1 us
Gas discharge tube 20 surges 5 us
Input Surge Protection
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
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
FinancialsComponent Price Quantity Total
Clock $2.34 4 $9.36Clock-Back Battery $4.28 1 $4.28Microcontroller $22.85 1 $22.85Switching Regulator $3.75 1 $3.75Schottky Diode $0.55 1 $0.55TVS Diode $0.73 1 $0.73Inductor $3.56 1 $3.56LCD Driver $1.75 1 $1.753-Digit 7-Segment Display
$2.91 1 $2.91
Ethernet Controller $5.83 2 $11.66Ethernet Connector $4.73 2 $9.46Super-Red LED $1.08 2 $2.16Cyclone Pro Programmer
$298.80 1 $298.80
Metal Oxide Varistor $0.56 1 $0.56Din Rail Connector $1.54 1 $1.54Case Donated 1 DonatedPCB $80.00 1 $80.00Pin Connector $0.15 3 $0.45Resistor $0.02 17 $0.34Capacitor $0.12 20 $2.40Total $457.11
Overall
Testing
Firmware
Hardware
Research
0 10 20 30 40 50 60 70 80 90
Completion Timeline