CAS Modbus RTU Parser

Have you ever needed to analyze a Modbus RTU message?
The CAS Modbus RTU parser can analyze a Modbus RTU message and tell you if there are any errors in the message, what type of messages it is, what data is being written or read from your device, what device the message came from, and more…Features:

  • Check for errors in Modbus RTU messages.
  • Analyze messages in a human readable forum.
  • Analyze raw hex data messages
  • Free. (No email required)



Executable (166k)
Please Read the copyright and disclamer before downloading this tool.

This is an example of a common Modbus RTU message being analyzed.

Modbus RTU message:
        [0b] [17] [00] [04] [00] [06] [00] [0f] [00] [03] [06] [00] [ff] [00] [ff] [00] [ff] [ab] [cd]
Frame Analysis
The frame has no errors.

Poll Analysis
Device Address  = 11      = 0x0b
Function        = 23      = 0x17 = Read or Write 4x Registers
Read Point Addr = 40005
Read Qty        = 6
Write Point Addr= 40016
Write Qty       = 3
	Write Data: Point Address  =40016   Value =255  =0x00ff
	Write Data: Point Address  =40017   Value =255  =0x00ff
	Write Data: Point Address  =40018   Value =255  =0x00ff


Version history

  • CAS Modbus RTU Parser v1.00gD (13 Aug 2009)
  • CAS Modbus RTU Parser v1.00fA (19 May 2005)
  • Corrected:some numbers intended for printing in hex were printing decimal
      • Corrected: If both poll and response selected then both poll and response are analysed. Previsouly not.
      • Corrected: If poll or response are exceptions then this is now recognized and printed correctly.
      • New:Can process client or server log files.
        • All lines containing ‘TX :’ or ‘RX :’ are processed as poll/response pairs.
        • For client files: TX indicates a poll and Rx indicates a reponse
        • For server files: TX indicates a response and Rx indicates a poll
        • Output is written to a file.
      • New: Screen output can now be copied to copy-buffer by click of a button
      • New: Checksum validation is done during frame validation phase.
      • Corrected: Sample message has valid checksum
      • Corrected: Auto update will now download the new installer instead of sending you to a webpage to download the new version.

Modbus for Field Technicians (Free!)

Learning about Modbus? Want to update your Modbus knowledge? This free EBook will guide you through basic and advanced Modbus topics.You can purchase a hardcopy of this book from Amazon or you can download the Modbus for Field Technicians for free.


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