Modbus

Modbus is a serial communications protocol published by Modicon in 1979 for PLCs; it is now a common industrial interconnect.

Wrong Baud Rate, ASCII/RTU mode, or polarity fails decode—prefer Auto Detect. See Settings.

Decode Settings

Channel:
- Tx: Modbus Tx channel.
- Rx: Modbus Rx channel. Field enabled (Enable) when checked. Default: cleared.
Transmission Mode: ASCII / RTU. Default: RTU.
Format:
- Auto Detect: Auto-detect manual options. Field enabled (Enable) when checked. Default: checked.
- Manual: Set the options below. Default: cleared.
  - Baud Rate: bits/s (about 110–2 M). Default: 9600.
  - Polarity: Idle high / Idle low. Default: Idle high.
  - Parity: None / Odd / Even. Default: None.
  - Data Bits: 7 / 8 / 9. Default: 8.
CRC Check: CRC check. Field enabled (Enable) when checked. Default: checked.
Adv. Report: Further decode in the report. Field enabled (Enable) when checked. Default: cleared.
Big-Endian: Arrange data Big-Endian. Field enabled (Enable) when checked. Default: cleared.
Waveform Area Settings:
- Decode: Show Tx or Rx in the waveform; Rx only when Rx is field enabled (Enable). Default conversion index often 0.
- Show Scale: Show scale on the waveform. Field enabled (Enable) when checked. Default: checked.