Modbus Trigger

Modbus trigger supports Simple Trigger (Start/End of frame, Parity Error, Break/Idle) or Clause Trigger with a data pattern. TravelBus provides a dedicated UART port.

See Settings and Clause Trigger.

Trigger Settings

Modbus Trigger (LA)

Modbus Trigger (TravelBus; extra channel source)

Because TravelBus has UART-specific channels, the Modbus trigger UI includes extra channel-source options.

• Channel: UART Port/LA Port. Polarity is required for LA Port. Default is LA; polarity Default is Idle High.
• Baud Rate: Select or type a baud rate. Default is 9600.
• Option:
  • Parity: None/Odd/Even. Default is None.
  • Mode: ASCII/RTU. Default is ASCII (index 0). Under RTU you may check 8-N-1 (8-N-2 is common in the field).
• Simple Trigger: Start of frame, End of frame, Parity Error, Break/Idle frame. Field enabled (Enable) when checked. Default all cleared.
• Clause Trigger: See Clause Trigger.
• State: ASCII/HEX input follows ASCII/RTU mode. Rx/Tx direction and Bypass are available; HEX up to 16 bytes. Enter a data pattern; unused bytes use XXh (Don't care).

Modbus State

Modbus State example

Modbus State example

Modbus State example

See also

• Modbus — Protocol Analyzer settings