Bus Monitors
The avionics busses ARINC-429 and high speed MIL-STD-1553 have been joined by commercial standards such as Ethernet, CAN-bus and FireWire. ACRA CONTROL provides ‘Parsers’, ‘Snarfers’ and ‘Packetizers’ to monitor a wide range busses in a standardized manner without interfering with the busses operation.
- Parser - Extracts specific data from a bus and places it into defined words along with status information. Data is triple buffered to ensure the data remains coherent. A MIL-STD-1553 parser is sometimes referred to as IRIG-106 Chapter 4 monitor.
- Snarfer – Places traffic and tags, along with content identifiers, into a FIFO that ensures data is not lost if read fast enough. For MIL-STD-1553 snarfing is sometimes referred to as Chapter 8 or All-bus monitoring.
- Packetizer – Coherently embeds multiple whole messages / frames / packets of various lengths in an IP packet. Because traffic and tags can be inferred from the location in the packet payload, content identifiers are not required and therefore less overhead / bandwidth is required. There are also overhead savings with respect to time and status information which can be IP packet wide.
| Bus | Parser | Snarfer | Packetizer |
|---|---|---|---|
| AFDX | ✓ | ||
| ARINC-429 | ✓ | ✓ | ✓ |
| ARINC-573/717 | ✓ | ||
| ASCB-D | ✓1 | ||
| CAIS | ✓ | ||
| CAN-bus | ✓ | ||
| CCDL / MCDL | ✓ | ||
| CSDB | ✓ | ||
| EF-2000 FCS | ✓ | ||
| Ethernet | ✓ | ✓ | ✓ |
| FiberChannel | ✓1 | ||
| FireWire | ✓ | ||
| IRIG 106 PCM | ✓ | ✓ | |
| MIL-STD-1553 | ✓ | ✓ | ✓ |
| Panavia | ✓ | ✓ | |
| RS-232/422/485 | ✓ | ✓ | ✓ |
| S200 FireWire | ✓ | ||
| Serial data bus | ✓ | ||
| STANAG-3910 | ✓ | ||
| TTP bus | ✓ | ✓ |
1 requires an external device