LINKTYPE_RTAC_SERIAL

Packet structure

+---------------------------+
| Relative TimeStamp (Left) |
|          (4 Bytes)        |
+---------------------------+
| Relative TimeStamp (Right)|
|          (4 Bytes)        |
+---------------------------+
|     Serial Event Type     |
|          (1 Byte)         |
+---------------------------+
|  UART Control Line State  |
|          (1 Byte)         |
+---------------------------+
|          Footer           |
|         (2 Bytes)         |
+---------------------------+
|          Payload          |
.                           .
.                           .
.                           .

Description

The Relative TimeStamp Left field gives the time stamp, in seconds since January 1, 1970, 00:00:00, of the packet, and the Right field gives the number of microseconds since that second. This is the same time stamp that appears in packet headers in pcap files, and can be easily be calculated from the time stamp that appears in Packet Blocks and Enhanced Packet Blocks in pcap-NG files, and can be ignored in those cases.

The Serial Event Type field represents the type of packet entry in the pcap file:

  • 0x00 - STATUS_CHANGE
  • 0x01 - DATA_TX_START
  • 0x02 - DATA_RX_START
  • 0x03 - DATA_TX_END
  • 0x04 - DATA_RX_END
  • 0x05 - CAPTURE_DATA_LOST
  • 0x06 - CAPTURE_COMPLETE
  • 0x07 - FRAMING_ERROR
  • 0x08 - PARITY_ERROR
  • 0x09 - SERIAL_BREAK_EVENT
  • 0x0A - SERIAL_OVERFLOW_EVENT

The UART Control Line State field shows the state of the serial UART lines (asserted, de-asserted) at the time of the packet generation:

  • 0x01 - Clear To Send
  • 0x02 - Data Carrier Detect
  • 0x04 - Data Set Ready
  • 0x08 - Request To Send
  • 0x10 - Data Terminal Ready
  • 0x20 - RING
  • 0x40 - MBOK

The Footer is reserved for future use

The payload is one of: DNP3, Modbus, IEEE C37.118 Synchrophasor or SELFM. The packet does not specify which it is; a program processing these packets must either have the payload type specified externally or must atempt to determine it heuristically.