1. Development background
The ARINC429 bus protocol was proposed by the U.S. Aviation Engineering Committee in July 1977 and was published and approved for use in the same month in the same year. Its full name is DITS, a digital information transmission system. The protocol standard specifies the digital information transmission requirements between avionics and related systems. ARINC429 is widely used in advanced civil aviation passenger aircraft, such as B-737, B757, B-767, Russian military aircraft also used a similar technology. Our corresponding standard is HB6096-SZ-01.
ARINC429 bus structure is simple, stable performance, strong anti-interference. The greatest advantage lies in its high reliability. This is due to decentralized control, reliable transmission, and good error isolation.
ARINC429 features are as follows:
1. One-way transmission method. Information can only be output from the transmission port of the communication device, and is transmitted via the transmission bus to the interface of other devices connected to it that need this information. However, the information must not be returned to the interface that has been specified as sending information. When two-way transmission is required between two communication devices, an independent transmission bus is used in each direction. Because there is no BC of the 1553B bus, the task and risk of information distribution are no longer concentrated.
2. Drive Capability Each bus can connect up to 20 receivers. Due to the small number of devices, there is ample time guarantee for information transfer.
3. The modulation mode uses a bipolar zero-reset tri-state code method.
4. The transmission rate is divided into two levels: high and low, and the bit rate of the high-speed working state is 100 Kb/s. The bit rate of the system at low speed is in the range of 12Kb/s~14.5Kb/s. The bit rate after the selection is within the error range of 1%. High and low rates cannot be transmitted on the same transmission bus.
5. The basic unit of transmission in synchronous mode is a word, each word consists of 32 bits. The bit synchronization information is carried in the signal waveform of the bipolar zero return code. The word synchronization is based on the zero-level time interval of at least 4 bits in the transmission period, and is the starting point of the first bit to be sent immediately after the word interval. The starting point for the new word.
According to the ARING 429 bus specification, each word format (binary or two-decimal) consists of 32 bits: 1-8 bits are label bits (LABEL). It flags the type of information included in this transfer word, that is, what the meaning of the transmitted code is. If the VHF information is transmitted, the number is octal number 030; if it is DME data, the number is octal number 201 or the like.
9-10 bits are Source Terminal Identification (SDI). It indicates that the source of the information or the terminal of the information, such as the tuning word of a control box, is to be sent to 3 VHF transceivers. It is necessary to indicate the terminal of the information, that is, to deliver the tuning word to that VHF receiver.
The 11-28 or 29 bit is a Data Field, which can be determined to be 11 to 28 or 11 to 29 depending on the type of the word. It represents the specific data that was determined. If the reference number is 030, the 11 to 29 bits are frequency data, and the BCD coded data format is used, namely bits 11 to 29.
Bits 29 to 30 or 31 are symbol status matrix bits (SSM), depending on the word type number 29 or 30 to 31. It indicates the characteristics of the data, such as South, North, Positive, Negative, etc. or its status. Use 30 to 31 bits (BCD coded) in VHF.
The 32-bit parity bit (P) is used to check if the transmitted data is valid. The check method is "1" on the 32nd bit when the sum of the high-level bits (i.e., a number of 1) appearing from 1 to 31 bits is even. If odd, "0" is displayed.
There are four zero cycles after sending each set of data, which is an isolation symbol to facilitate sending the next set of data.
Communication control files and data transmissions are implemented using commands and response protocols. The transmission data are binary data words and ISO5 alphabet characters. The structure of the file is that a file consists of 1 to 127 records, and a record consists of 1 to 126 data words.
1. File and Data Transfer Protocol When the sender has data to send to the receiver, the sending device sends the “Request to send†initial word through the transmission bus. After receiving the initial word, the receiver “Clears†the data through another bus. Sending "initial word" as a reply indicates that the receiver is ready to receive data. The sender receives this reply and sends the first record first.
2. The transmission control word transmission words include initial words, intermediate words and end words. The 30th and 31st bits of each word of the file transmission represent the word type. The file transmission data is ISO5 letters and binary data words. The label of the file transfer is determined according to the application of the file, including the management computer system communicates with each other. If priority control capability is required, it is necessary to assign more than one label to the files in these applications.
At present, there is no standard software that meets the general ARINC429 function on the market. It is particularly important to develop a representative ARINC429 software. The ARINC429 Data Bus Analyzer developed by Olimp Technology is a representative ARINC429 software in China.
2. Software introduction
a) Development Environment:
Operating System: WinXP
Development language: C++
b) Operating environment:
Operating System: Win98/2000/XP/Win7
Memory size: 1G and above hard disk space: 160G and above
c) Main functions:
Support interface: PCI, cPCI/PXI, PC/104, PC/104-Plus, USB, etc. Man-machine interface: Operational specification, flexible and friendly.
Automatically search for ARINC429 board in the system and connect to return operation handle.
Trigger mode settings can be set to send the channel trigger mode, you can also set the receive channel trigger mode. The trigger mode includes internal trigger and external trigger.
Receive mode setting: You can set the polling receive mode and interrupt receive mode. When set to interrupt receive mode, you can also set how many words are received to generate an interrupt.
Receiving data processing: Can be set to display to the list, or saved to a file, or displayed and saved. You can choose to save the directory.
List box: Can be set to whether to automatically scroll, whether to automatically clear the list, when set to automatically clear the list, you can set more than the number of rows to clear the list automatically.
Module attributes: The model, manufacturer, logic number, etc. of the currently selected module can be displayed.
Set the parameters of the sending channel to support parameter setting for all sending channels of the selected module, setting the allow/inhibit channel, setting the sending baud rate, setting the parity, setting the frame interval, setting the idle bit, and editing the sending data.
Set receiving channel parameters Supports setting of all the receiving channels of the selected module, setting the enable/disable channels, setting the receiving baud rate, setting the SDI filter, and editing the Label filter data.
Start/stop sending/receiving data. You can also save the received data to a file and name it by date.
The ARINC429 data analysis function can load data from a file, automatically parse it into a list, and then search by channels, channel aliases, and data words. You can also export the search results to a file for other purposes.
Support simultaneous control of multiple modules in the same system.