Arinc 429 Serial Port Adapter

The RTX Serial Port Adapter (RTX SPA429) is a family of compact ARINC 429 devices that plugs into a serial port (or a USB port with an adapter) of any computer, running any operating system, and enables the user to access up to 4 ARINC 429 channels easily and inexpensively. The standard RTX SPA429 can transmit on 2 ARINC channels and receive from 2 ARINC channels in either high speed (100 Kbps) or low speed (12.5 Kbps) data rates (or both simultaneously). The RTX SPA429 can process all 4 channels at full data rates. There are no restrictions on the number of labels that can be transmitted or received. There are no batteries to replace or charge and no power cords to hook up (the SPA gets all of its power from the RS232 port). No installation or setup is required; no device drivers are necessary. Just plug it in to a RS232 serial port (or a USB port with a standard USB/RS232 adapter) and run your (or our) application software. Its not even necessary to power down the computer to install the RTX SPA429. Any program, written in any language, for any computer running any operating system can transmit and receive ARINC 429 data as long as the program can send and receive data to/from the serial port. If you're writing your own software, a Windows API is included to make programming simple. When used with your software, or with our VORTEX Windows GUI, the RTX SPA429 can be the heart of a powerful and sophisticated ARINC 429 system that is versatile, portable, inexpensive, and easy to use.

The ARINC 429 Transmitters

There can be up to 4 ARINC 429 transmit channels on the RTX SPA429 adapter. In order for the RTX SPA429 to construct an ARINC 429 data word, 5 bytes of data need to be sent to the serial port that the RTX SPA429 is attached to. Any application, on any computer, using any operating system, that can send 5 bytes of data to an RS232 serial port, can transmit ARINC 429 words. The 5 bytes which are send to the RTX SPA429, are combined by the adapter, to form the 32 bit ARINC 429 word which is then transmitted on the specified ARINC channel. The RTX SPA429 will automatically generate an appropriate parity bit.

The ARINC 429 Receivers
In a manner similar to the transmission of ARINC 429 data, the RTX SPA429 receivers translate each incoming 32 bit ARINC 429 data word into 5 bytes and sends them to the attached RS232 serial port. Any application, on any computer running with any operating system, that can read 5 bytes of data from a RS232 serial port, can read from an ARINC 429 data bus. ARINC data words can be buffered within the RTX SPA429 adapter. If the host computer is unable to keep up with the incoming data, the RTX SPA429 can buffer up to 40 incoming ARINC 429 data words, without loosing any data. The RTX SPA429 can also filter incoming ARINC 429 data word, if desired. By software command, the RTX SPA429 adapter can be configured to reject or accept any number of labels, and only allow through specified labels. Each channel can have its own separate list of labels which will be allowed to pass. This eliminates the need for software to scan all the incoming data, for labels of interest.

The Software Interface
The RTX SPA429 adapter includes the RTX Applications Program Interface (API), which is a Windows only interface. The RTX ARINC 429 API enables user written software, the functional capability to transmit and receive any data on any channel. The API converts high level User Commands into the 5 byte RTX format. It also provides the ability to setup the RTX SPA429 adapter to filter out (or allow through) any label(s) desired, on a per channel basis. There is no limit to the number of labels that can be enabled or disabled. Using the API, a programmer can access the functions of the SPA, without regard to the details of the hardware interface to the RTX SPA429 adapter, eliminating the need to convert the data between 32 bits ARINC words and the 5 byte RTX format. The API is in the form of a Windows DLL, and any program which can interface with a Windows DLL, such as LabView, can utilize the RTX ARINC 429 API. There is no additional cost for the API, and no licensing fees.

RTX also sells VORTEX, a Windows based Graphical User Interface (GUI) which is perfect for most applications. The Vortex GUI provides access to all transmit and all receive functions of the RTX SPA429 adapter, in a Windows environment. In addition to simplifying transmission and reception of data on any channel, the Vortex GUI also can perform Engineering Units Conversion of data to be transmitted or received and real-time storing of incoming data onto a file, for later playback and analysis. The receive portion of VORTEX can display the received data in multiple formats: each ARINC word can be displayed on its own line, or only the most recently received ARINC word per label can be displayed. In addition, the VORTEX Aircraft Emulator Option (AEO), enables the capability to transmit a previously recorded data file, onto the SPA's transmit channels, thereby reproducing in the lab the ARINC 429 scenario as it was recorded in the field.

Optional Configurations
The standard RTX SPA429 configuration (PN: RTX429/SPA5-2T2R) has 2 transmit channels and 2 receive channels. The RTX SPA429 can be purchased with extended temperature range (-40 degrees C to +85 degrees C), or with channel configurations of 4 Transmit channels and 0 Receive channels or 0 Transmit channels and 4 Receive channels. The SPA MONITOR package, consisting of a single receive channel and includes a single receive channel version of VORTEX, is available for a special combined price. The SPA can also be purchased as an ARINC 717/573 receiver. All SPA configurations can operate from a USB port with a standard RS232/USB adapter.