PicoScope's Modbus analysis tool

PicoScope’s Modbus decoder for troubleshooting PLC applications

  • Pico Technology has enhanced its PicoScope analysis capabilities with the addition of Modbus ASCII and Modbus RTU decoders.
  • The analysis of Modbus (RS-232/RS-485) signals offers the possibility of troubleshooting industrial PLC applications.
  • PicoScope is an USB-connected PC oscilloscope, offering six test and measurement instruments including protocol analysis.

The Modbus decoder is available for all PicoScope models, from the low-cost 2000 Series through to the top-of-the-range 6000 Series. For sources that are not referenced to earth, such as RS-485, the recently introduced PicoScope 4444 Series permits differential measurements on up to four channels without an external active differential probes. PicoScope includes a set of automated and ruler-based on-screen measurements as standard.

Managed by the Modbus Organization, this protocol is used to connect industrial electronic devices. The PicoScope decoder supports master and slave devices, standard and custom baud rates, and one or two ID bytes. Hundreds or thousands of Modbus messages can be captured with each acquisition using the deep memory provided in most PicoScope models.

Each message is stored with start/end timing information, device IDs, function codes, transmitted data and CRC information as well as data validity checks. The table of acquired messages can be analyzed directly within PicoScope or can be exported in CSV format for offline analysis. A link file helps to analysis by cross-referencing hexadecimal field values, such as the slave ID, to plain text. Clicking on a decoded packet takes you to the corresponding point on the analog waveform.

Modbus decoding and analysis is included as standard in the latest PicoScope beta version 6.13, which now supports a total of 18 serial protocols. The software is available free of charge for all existing and new PicoScope users and can be downloaded from Picotech website.