The new “Modbus over Serial Line” feature helps the user in three main ways: It displays and analyses monitored Modbus messages in an easily viewed way, with automatic validation of CRC/LRC, and instant display of RTU timing errors; It allows the user to conveniently define and transmit test messages in Modbus format, without having to calculate CRC/LRC values; It can download captured data to a PC, so it appears in Modbus format.
It works with either “ASCII” or “RTU” (binary) transmission mode framing. The facility is provided on all new SDA-02 analysers and is available as a firmware upgrade to those sold since May 2005.
An application note is available which explains the facility in full.