The DNx-429-516 ARINC-429 interface from United Electronic Industries (UEI) is designed for use with the company’s UEI’s Cube and RACKtangle chassis. It is compatible with ARINC-429 commercial aviation data standard.
This is an update to an earlier version, the DNx-429-516-024, and includes an additional 8 dedicated RX channels.
The DNx-429-516. Image from UEI
According to UEI's press release on the board, it "provides unprecedented flexibility to record, playback, process, and test... ARINC-429 traffic."
So, for those of us not in the aerospace industry, what is the ARINC-429 standard?
What Is ARINC-429?
ARINC-429 is the technical data transfer standard for avionics data bus employed by commercial aircraft. Within it are defined the physical and electrical standards for the two-wire twisted pairs that comprise the bus.
Messages are typically contained in one 32-bit long word, and transmission is at either 12.5 or 100 kilobits per second. The information is self-clocked, so no separate line is required for clocking.
Specifications for the DNx-429-516
There are several channels on the DNx-429-516, including 16 TX/RX channels, which can be used on a channel-by-channel basis as RX channels by disabling the corresponding TX drivers. There are also 8 dedicated RX channels.
As seen in the block diagram below, the protocol controller uses a digital signal processing block with an FPGA, which has communication protocol functions embedded into it.
Block diagram for the DNx-429-516 TX single-channel. Image from the datasheet. Click to enlarge.
As ARINC-429 specifies, data transmission can be high speed (100 kHz), low speed (12.5 kHz), or other frequencies if need be on a channel-by-channel basis. The device manages ARINC-429 traffic while maintaining data integrity, "even when all channels are set in high-speed mode."
Transmission of all channels is scheduled by a hardware-controlled scheduler (with a transmission schedule resolution of 100 microseconds). Modes of transmission include a TX mode where a label is transmitted only upon receipt of data from a pre-programmed lab.
Alternatively, they can transmit asynchronously, with three priorities:
- High-priority data: Sent immediately, regardless of any scheduling constraints; will send upon completion of current transmission
- Standard-priority data: Sent during times when no scheduled data is being transmitted
- Low-priority data: Sent when no scheduled, high-, or standard-priority data is being transmitted; streamed from a 256-word FIFO
The UEIDAQ Framework offers an API to access and control the DNx-429-516, as well as for other UEI data acquisition devices. UEI asserts that the API is easy to use and supports most popular operating systems and programming languages.
As might be expected for such an important application with an almost universal standard, there is much interest in ARINC-429 devices by a multitude of manufacturers. Here are two.
- North Atlantic Industries offers the AR429/575 module. This device provides up to six programmable ARINC-429 channels. Each channel is software selectable for transmit or receive, and for high or low speed. The unit is for either ARINC-429 or for the older ARINC-575 standard.
- Alta Data Technologies offers a wide range of ARINC-429 Interface boards. One specific item is the PMC-A429HD, which offers 16, 32 or 48 channels of RX and TX ARINC-429 channels.
Tell us about your experience designing with the ARINC-429 standard in the comments below.