2.1.1
ARINC 429 Signal Converters
Summary Description
The NEXSYS ARINC 429 Signal Converter is either a Series N (8 Pin) or Series R (12 Pin) autonomous ARINC 429 receiver that includes the protocol logic necessary to capture and decode an ARINC 429 data word. The 32-bit data word is then converted into a discrete output, see Figure 2.1.1.0-A. Some configurations are also capable of performing interface solutions for encoding applications by performing the multi-bit decode operation.
The NEXSYS Signal Converter is available in three configuration types based on the requirements for data conversion and output control:
- Single-Bit Converter (SR429/1M), see Section 2.1.1.1
- Multi-Bit Converter (SR429/4M), see Section 2.1.1.2
- Multi-Bit Decoding Converter (SR429/4D), see Section 2.1.1.3
The simple input-pin interface does not rely on any microcontroller, software or firmware control, eliminating the qualification requirements of DO-178 or complex hardware (DO-254).
The NEXSYS ARINC 429 Signal Converter (SR429/1M, /4M, /4D) is a commercial-off-the-shelf (COTS) item. This standard catalog hardware includes features to allow for flexible interface design solutions while also meeting aircraft performance standards. The SR429 is designed, tested, and qualified to MIL-PRF-22885/116, MIL-PRF-22885/117, DO-160 and MIL-STD-461 requirements. Specifications are available in our MIL-PRF and DO-160 Documents page, and the qualification table is available in Appendix A.
Standard Input Characteristics
The NEXSYS ARINC 429 Signal Converter inputs are Power (28V), Ground (GND), Receive A (RXA) and Receive B (RXB). See additional sections for specific details concerning the Input/Output (I/O) interface. The inputs include the following characteristics for custom data conversion and output control. Input circuity is diode isolated, buffered, and debounced for reliable operation.
28V (PIN 4): Operating voltage (Nom.), 8 mA Current Draw (Max).
GND (PIN 5): Continuous Ground required, otherwise, inadvertent operation could occur.
RXA (PIN 2), RXB (PIN 3): Two-wire data Receive (RX) interface that autonomously receives the ARINC 429 unit of Transmission (TX).
RXA, RXB Installation Notes: The industry standard connection should include two wires that are twisted pairs with shielded ground cabling, which provides a balanced differential signal transmission. Multiple converters wire together, in parallel chain termination method, see Figure 2.1.1.0-B.
Note: ARINC 429 converters are tested to operate without twisted or shielding wires.
Standard ARINC 429 Configuration Options
The NEXSYS ARINC 429 Signal Converters can be customized to provide an application-specific control interface to other avionics equipment. Standard ARINC 429 data bus protocol and 32-bit word format options are configured, by utilizing the online Part Configurator.
Label: The specification of an octal (base-8) label (000-377). When energized, if a loss of data should occur, the converter latches the last valid transmission until valid data is once again received.
Data Bit(s): The specification of data bit (11-31) to be used as Discrete Outputs or to be used in Binary Outputs, see Standard Output Characteristics.
Source/Destination Identifiers (SDI): The specification to enable or disable (ignore) bits 9 and 10, used as an extension of the label for valid label identification.
Transmission Speed: The specification of the speed by which a converter receives (RX) the ARINC 429 unit of transmission (TX). The options are either High speed (100 kbps) or Low speed (12.5 kbps).
Parity: The specification of parity error detection, which is a designated check-bit (32), to ensure that valid data is received (RX) by checking for correct odd parity of received ARINC 429 words. When the parity checking option is enabled, data is used only if the parity is correct. When the parity checking option is disabled, the parity state is ignored.
Standard Output Characteristics
NEXSYS Signal Converters (SR429/1M, SR429/4M, and SR429/4D) receive (RX) an ARINC 429 data transmission (TX), which is decoded and converted into active discrete output(s). One or more single (unary) bits in the ARINC 429 data word can be converted into discrete outputs, depending upon the configuration type that is specified. The available configuration types provide up to three distinct output control activation options; Discrete Outputs, Decoded Outputs and the Failure Output.
All outputs are open-drain High-Z (Open) when not active. The output load capacity is 1.0 A for the SR429/1M and 0.5 A for SR429/4M and SR429/4D , see Figure 2.1.1.4-A (Operating Parameters) for electrical load rating types.
Output Option | DATA BIT (Value) |
DISCRETE OUTPUT (Signal Level) |
Standard | 1 | High-Z (Open) |
0 | Low (Ground) | |
Inverted | 1 | Low (Ground) |
0 | High-Z (Open) |
Discrete Outputs: Two Active Output options are available when converting the unary ARINC data bit to a Discrete Output: Standard, High-Z (Open) when Bit = 1 or Inverted, or Low (Ground) when Bit = 1. When Bit = 0 the output is orthogonal to the specified level when Bit = 1, see Figure 2.1.1.0-C.
Output Option | BINARY DECODE (Variation) |
DECODED OUTPUT (Signal Level) |
Low (Ground) when Decode Variation = TRUE |
BD = TRUE | Low (Ground) |
BD = FALSE | High-Z (Open) | |
High-Z (Open) when Decode Variation = TRUE |
BD = TRUE | High-Z (Open) |
BD = FALSE | Low (Ground) |
Decoded Outputs - Active Outputs can also represent the Binary Decode (BD) of multiple bits, and the Decoded Outputs options are: the BD variations of two or three data bits in the SR429/4D or of the Sign/Status Matrix bits (30, 31) available in the SR429/4M. Active Decoded Outputs are specified as Low (Ground) or High-Z (Open) when the decode = TRUE, see Figure 2.1.1.0-D.
Data bits that are specified for the BD function are positioned from MSB (Most Significant Bit) to LSB (Least Significant Bit). The MSB may also function as the sign bit in the two’s complement operation to represent a negative value (i.e., negative altitude, voltage, or temperature), with the addition of other NEXSYS components.
Output Option | IC (Status) | FAILURE OUTPUT (Signal Level) |
Health | NORM | Low (Ground) |
FAIL | High-Z (Open) | |
Watchdog | NORM | High-Z (Open) |
FAIL | Low (Ground) |
Failure Output - The NEXSYS ARINC 429 Signal Converter is also designed to monitor power and health of the internal IC receiver and offers two options for failure detection, Health and Watchdog, see Figure 2.1.1.0-E. Both options monitor the internal IC and produce an Active Output upon failure of the receiver IC and/or failure to receive valid ARINC data within a specified time buffer. The Health option also monitors loss of unit power.
Health and Watchdog include a buffer-timer that is intended to monitor that valid data is received within a specified time. Health and Watchdog timing is specified during part number configuration, and the options are 0.5 s, 1.0 s. 1.75 s, 2.5 s, 5.0 s, 10.0 s, 15.0 s.
In the SR429/1M , only the Health version of the Failure Output is available which can be combined with additional external failure discretes to activate the Failure Output (FAIL, PIN 6), see ARINC 429 Single-Bit Converter (SR429/1M).
2.1.1.1
ARINC 429 Single-Bit Converter (SR429/1M)
See Figure 6.0.0.0-C for pinout variations by form factor |
The ARINC 429 Single-Bit Converter (SR429/1M) is a Series N (8 Pin) device that offers one Discrete Output (OUT, PIN 8) from a single bit and one Failure Output (FAIL, PIN 6) that activates when the Fail Sense Circuitry detects a failure condition, see Figure 2.1.1.1-A. Output options are shown below in table Figure 2.1.1.1-B.
The FAIL output (FAIL, PIN 6) from the Fail Sense Circuitry is a Health Failure Output, defined as Normal = Low (Ground) and Fail = High-Z (Open). The primary purpose of the FAIL output is to monitor the power and health of the internal IC. The Fail Sense Circuitry can be bypassed if unused.
Optionally, the SR429/1M provides two (IN 1, PIN 1 and IN 2, PIN 7) independent failure inputs to the Fail Sense Circuitry that allows simultaneous monitoring of the internal IC health and signal level transitions from two external failure inputs. IN 1 and IN 2 are inputs with specific failure signal definitions.
- IN 1 (PIN 1): Triggers the FAIL output (PIN 6) upon a fixed input level transition from Normal = High, High-Z (Open) or > +20 VDC to Fail = Low (Ground) or < +6 VDC (). IN 1 may remain disconnected if unused.
- IN 2 (PIN 7): Triggers the FAIL output (PIN 6) upon one of two selectable input level transitions as described below (). IN 2 must remain connected to the specified Normal signal level if unused.
- Normal = Low (Ground) or < +6 VDC to Fail = High, High-Z (Open) or > +20 VDC.
- Normal = High, High-Z (Open) or > +20 VDC to Fail = Low (Ground) or < +6 VDC (similar to IN 1).
When either IN 1 or IN 2 detects a signal level transition as defined above, or the internal IC has failed, the FAIL output transitions from Normal = Low (Ground) to Fail = High-Z (Open).
Pin 6 (FAIL) | Pin 8 (OUT) | |
H | 11 to 31 | |
OPTION DEFINITION | ||
H | Failure Output (Health) is Fail = High-Z (Open). | |
11 to 31 | For a single-bit, 11 to 31 inclusive, Discrete Output can be specified as Standard = High-Z (Open) when Bit = 1 or Inverted = Low (Ground) when Bit = 1. |
2.1.1.2
ARINC 429 Multi-Bit Converter (SR429/4M)
The ARINC 429 Multi-Bit Converter (SR429/4M) is available as a NEXSYS Series N (8 Pin) or Series R (12 Pin) signal converter.
-
See Figure 6.0.0.0-C for pinout variations by form factor
See Figure 6.0.0.0-D for pinout variations by form factor
- Series R (12 Pin) SR429/4M: Provides four Discrete or Failure Outputs (PINS 1, 6-8) plus four additional outputs (PINS 9-12), see Figure 2.1.1.2-B. Discrete Outputs and Failure Outputs can be repeated to avoid external splicing. The additional outputs (PINS 9-12) can be used as Decoded Outputs of the Sign/Status Matrix (SSM) bits 30 and 31 or as additional Discrete or Failure Outputs. When additional Discrete Outputs are specified, the signal levels will be the inverted value of the initial four Discrete Outputs. Output options, including the ability to repurpose SSM decode variation 00 (PIN 9) with additional data, are shown in detail in, see Figure 2.1.1.2-C.
PIN 1 | PIN 6 | PIN 7 | PIN 8 | PIN 9 | PIN 10 | PIN 11 | PIN 12 | |
11 to 31, H or W | 11 to 31, H or W | 11-31, H or W | 11 to 31, H or W | - | - | - | - | |
11 to 31, H or W | 11 to 31, H or W | 11 to 31, H or W | 11 to 31 | [9] | [10] or H | [11] or H | [12] or H | |
11 to 31, H or W | 11 to 31, H or W | 11 to 31, H or W | H or W | H or W | [10] or H | [11] or H | [12] or H | |
11 to 31, H or W | 11 to 31, H or W | 11 to 31, H or W | 11 to 29 | H or W | [10] or H | [11] or H | [12] or H | |
11 to 29 | 11 to 29 | 11 to 29 | 11 to 31, H or W | SSM00 | SSM01 | SSM10 | SSM11 | |
11 to 29 | 11 to 29 | 11 to 29 | 11 to 31, H or W | H or W | SSM01 | SSM10 | SSM11 | |
11 to 29 | 11 to 29 | 11 to 29 | 11 to 31 | [9] | SSM01 | SSM10 | SSM11 | |
11 to 29 | 11 to 29 | 11 to 29 | H or W | H or W | SSM01 | SSM10 | SSM11 | |
OPTION DEFINITION | ||||||||
11 to 29, 11 to 31 | For a single bit, 11 to 29 or 11 to 31 inclusive, Discrete Output can be specified as Standard = High-Z (Open) when Bit = 1 or Inverted = Low (Ground) when Bit = 1. | |||||||
H | Failure Output is High-Z (Open) when Health Monitor = Fail. | |||||||
W | Failure Output is Low (Ground) when Watchdog = Fail. | |||||||
[9] | Will be the same Bit specified on PIN 8, Discrete Output can be specified as Standard = High-Z (Open) when Bit = 1 or Inverted = Low (Ground) when Bit = 1 regardless of output selection for PIN 8. | |||||||
[10] | Will be the same Bit specified on PIN 7, Discrete Output is Inverted = Low (Ground) regardless of output selection for PIN 7. | |||||||
[11] | Will be the same Bit specified on PIN 6, Discrete Output is Inverted = Low (Ground) regardless of output selection for PIN 6. | |||||||
[12] | Will be the same Bit specified on PIN 1, Discrete Output is Inverted = Low (Ground) regardless of output selection for PIN 1. | |||||||
SSM00 to SSM11 | Binary Decode of SSM Bits (Bits 30 and 31), Binary Outputs can be specified as High-Z (Open) when DECODE = TRUE or Inverted = Low (Ground) when DECODE = TRUE. | |||||||
Note: [ ] Bracket denotes Pin Number. |
2.1.1.3
ARINC 429 Multi-Bit Decoding Converter (SR429/4D)
The ARINC 429 Multi-Bit Decoding Converter (SR429/4D) is available as a NEXSYS Series N (8 Pin) or Series R (12 Pin) component.
The SR429/4D can be configured in two standard types of decoding:
- 2 x 4 Decoder: Performs a Binary Decode (BD) of two ARINC data bits producing four Decoded Outputs. The 2 X 4 Decoding Converter can be configured as a Series N (8 Pin) device, see Figure 2.1.1.3-A or a Series R (12 Pin) device with additional outputs, see Figure 2.1.1.3-B.
- 3 x 8 Decoder: Performs a Binary Decode (BD) of three ARINC data bits producing eight Decoded Outputs. The 3 X 8 Decoding Converter is configured as a Series R (12 Pin) device, see Figure 2.1.1.3-D. BD variations 000 and/or 111 can be repurposed as Discrete or Failure Outputs.
SR429/4D with 2 x 4 Decoder
-
See Figure 6.0.0.0-C for pinout variations by form factor
See Figure 6.0.0.0-D for pinout variations by form factor - Series R (12 Pin) 2 x 4 Decoder: Eight total outputs. Four Decoded Outputs (PINS 9-12); each output is a Binary Decode (BD) variation (00, 01, 10, 11) of two bits according to the ARINC 429 word protocol, see Figure 2.1.1.3-B. Additional output options include the ability to repurpose the BD variation 00 (PIN 9) and/or the BD variation 11 (PIN 12) with additional data. Four additional outputs (PIN 1, 6-8) are available for Discrete or Failure Outputs, see Figure 2.1.1.3-C for detail of the output options for all Series R pins.
PIN 1 | PIN 6 | PIN 7 | PIN 8 | PIN 9 | PIN 10 | PIN 11 | PIN 12 | |
DEC00 | DEC01 | DEC10 | DEC11 | - | - | - | - | |
11 to 29 | DEC01 | DEC10 | DEC11 | - | - | - | - | |
DEC00 | DEC01 | DEC10 | 11 to 31, H or W | - | - | - | - | |
11 to 29 | DEC01 | DEC10 | 11 to 31, H or W | - | - | - | - | |
11 to 29 | MSB (11 to 31, H, W) | LSB (11 to 31, H, W) | 11 to 31, H or W | DEC00 | DEC01 | DEC10 | DEC11 | |
11 to 29 | MSB (11 to 31, H, W) | LSB (11 to 31, H, W) | 11 to 31 | [9] | DEC01 | DEC10 | DEC11 | |
11 to 29 | MSB (11 to 31, H, W) | LSB (11 to 31, H, W) | H or W | H or W | DEC01 | DEC10 | DEC11 | |
11 to 29 | MSB (11 to 31, H, W) | LSB (11 to 31, H, W) | 11 to 29 | H or W | DEC01 | DEC10 | DEC11 | |
OPTION DEFINITION | ||||||||
DEC00 to DEC11 | Binary decode variations for specified label and bits; Binary Outputs can be specified as Low (Ground) or High-Z (Open) when DECODE = TRUE. | |||||||
11 to 29, 11 to 31 | For a single bit, 11 to 29 or 11 to 31 inclusive, Discrete Output can be specified as Standard = High-Z (Open) when Bit = 1 or Inverted = Low (Ground) when Bit = 1. | |||||||
H | Failure Output is High-Z (Open) when Health Monitor = Fail. | |||||||
W | Failure Output is Low (Ground) when Watchdog = Fail. | |||||||
[9] | Must be the same Bit specified on PIN 8, Discrete Output can be specified as Standard = High-Z (Open) when Bit = 1 or Inverted = Low (Ground) when Bit = 1 regardless of output selection for PIN 8. | |||||||
MSB, LSB | Discrete Output of Most/Least significant bit used in 2 x 4 decoder. Discrete Outputs can be specified as Standard = High-Z (Open) when Bit = 1 or Inverted = Low (Ground) when Bit = 1. | |||||||
Note: [ ] Bracket denotes Pin Number. |
SR429/4D with 3X8 Decoder
-
See Figure 6.0.0.0-D for pinout variations by form factor
PIN 9 | PIN 10 | PIN 11 | PIN 12 | PIN 1 | PIN 6 | PIN 7 | PIN 8 | |
DEC000 | DEC001 | DEC010 | DEC011 | DEC100 | DEC101 | DEC110 | DEC111 | |
11 to 31, H or W | DEC001 | DEC010 | DEC011 | DEC100 | DEC101 | DEC110 | DEC111 | |
DEC000 | DEC001 | DEC010 | DEC011 | DEC100 | DEC101 | DEC110 | 11 to 31, H or W | |
[9] | DEC001 | DEC010 | DEC011 | DEC100 | DEC101 | DEC110 | 11 to 31 | |
H or W | DEC001 | DEC010 | DEC011 | DEC100 | DEC101 | DEC110 | 11 to 29, H or W | |
DEC000 | DEC001 | DEC010 | DEC011 | DEC100 | DEC101 | DEC110 | DEC111 | |
11 to 31, H or W | DEC001 | DEC010 | DEC011 | DEC100 | DEC101 | DEC110 | DEC111 | |
DEC000 | DEC001 | DEC010 | DEC011 | DEC100 | DEC101 | DEC110 | 11 to 31, H or W | |
OPTION DEFINITION | ||||||||
DEC000 to DEC111 | Binary decode variations for specified label and bits; Binary Outputs can be specified as Low (Ground) or High-Z (Open) when DECODE = TRUE. | |||||||
11 to 29, 11 to 31 | For a single bit, 11 to 29 or 11 to 31 inclusive, Discrete Output can be specified as Standard = High-Z (Open) when Bit = 1 or Inverted = Low (Ground) when Bit = 1. | |||||||
H | Failure Output is High-Z (Open) when Health Monitor = Fail. | |||||||
W | Failure Output is Low (Ground) when Watchdog = Fail. | |||||||
[9] | Must be the same Bit specified on PIN 8, Discrete Output can be specified as Standard = High-Z (Open) when Bit = 1 or Inverted = Low (Ground) when Bit = 1 regardless of output selection for PIN 8. | |||||||
Note: [ ] Bracket denotes Pin Number. |
2.1.1.4
ARINC 429 Signal Converters, Operating Parameters
Description | Parameters |
Operating Parameters | |
Operating Voltage (Max./Nom./ Min.) | +32 VDC /+28 VDC/+18 VDC |
Power Supply Input Current | 8 mA (Maximum) |
Reset Time from Power Loss at 25°C | 5 sec (Minimum) |
Hold Up Time from Power Loss at 25°C | 200 ms (Minimum) |
Input Parameters | |
IN 1, IN 2 (SR429/1M) Input Timing at 25°C | 5 ms (Typical) |
IN 1, IN2 (SR429/1M) Low Level Input Current (IIL) at 25°C | 1 mA (Maximum) |
* IN 1, IN 2 (SR429/1M) Low Level Input Voltage (VIL) at 25°C | < +6 VDC |
* High (SR429/1M) Level Input Voltage (VIH) at 25°C | > +20 VDC |
ARINC 429 Inputs (SR429/1M, SR429/4M, SR429/4D) | IAW ARINC 429 Protocol |
IN 1, IN 2 inputs are diode isolated | |
Output Parameters | |
Output Load Capacity | SR429/1M: Fused MOSFET - 1.0 A (Resistive), 0.5 A (Motor/Inductive/Lamp) SR429/4M, SR429/4D: IntelliFET® 0.5 A (Resistive/Motor/Inductive/Lamp) |
On-State Resistance at 25°C | SR429/1M: Typical 0.07 ohms / Maximum 0.09 ohms SR429/4M, SR429/4D: Typical 0.4 ohms / Maximum 0.6 ohms |
Off-State Resistance at 25°C | SR429/1M: Open Drain (High-Z), Fuse-Protected MOSFET, +32 VDC Maximum SR429/4M, SR429/4D: Open Drain (High-Z), Self-Protected IntelliFET®, +32 VDC Maximum |
Temperature | |
Operating Temperature | -55°C to +85°C |
Non-Operating Temperature | -55°C to +125°C |
Reliability MIL-HDBK-217F, Notice 2 |
|
Airborne Inhabited Cargo (AIC) at +40°C Continuous Operation |
SR429/1M MTBF = 116,317 hrs SR429/4M, SR429/4D MTBF = 103,012 hrs |
* VIL and VIH specifications are in reference to unit Ground. |
For Qualification Summary, see Appendix A.