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CPTT and MODBUS

[ MODBUS ] was developed by Modicon in the 70s. It is a simple way to build a Master/Slave connection to an IED (Intelligent End Device).

MODBUS has spread strongly worldwide.

MODBUS serial

MODBUS is used as a simple transmission protocol to terminal devices (RTUs oder IEDs). It has general abilites within the context of SCADA applications.
The messages are generally transmitted through serial connections.

COMPROTware:Testtool offers in this protocol:

  • Simulation of Master and Slave Station.
  • Extensive state engine to implement protocols.
  • Monitoring on the serial line (seriellen Leitung).
  • Interactive input of messages.
  • Different application oriented view formats for message traffic.
    • E.g. 2 registers combined to a 32 bit integer or 32 bit float value.
    • The byte order (endianness) can everytime be changed from MODBUS standard "high-low" ("big endian", "MSB") to "low-high" ("little endian", "LSB").
To get an impression of MODBUS serial in CPTT, here is a link to an example file with MODBUS serial protocol traffic:
 1812171739-SModbusSerial-Clock.mlg

The linked MODBUS serial-MLG file is very large, it consists of more than 1,100,000 Frames. With this file we like to demonstrate that CPTT can handle large-scaled protocol traffic trouble-free.

This page describes how to install CPTT in viewer version (cost-free), how to access the MLG file and explains some CPTT formatting and filtering options.


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MODBUS TCP/IP

MODBUS TCP/IP is intended for connections through the TCP internet protocol. It has the same Application Layer message format but a different Link Layer frame format as MODBUS serial.

COMPROTware:Testtool offers in this protocol:

  • Simulation of Master and Slave Station.
  • Extensive state engine to implement protocols.
  • Master and Slave simulation via TLS-secured TCP/IP connection.
  • Network Monitoring under MS Windows.
  • Interactive input of messages.
  • Different application oriented view formats for message traffic.
    • E.g. 2 registers combined to a 32 bit integer or 32 bit float value.
    • The byte order (endianness) can everytime be changed from MODBUS standard "high-low" ("big endian", "MSB") to "low-high" ("little endian", "LSB").



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Any questions regarding CPTT? Please contact us:
e-mail cptt@realthoughts.de