The Diagnostic Manager is the software and interface to the fieldbus physical layer. It communicates simultaneously with all diagnostic modules. The expert system learns the conditions of each segment individually and provides feedback in clear text - no more guessing! Reports, alarm lists, and historic data can be exported for detailed analysis.
Advanced Diagnostics create notifications of type "maintenance required" or "out of specification". They never generate alarms, as the fieldbus physical layer is very stable. Conditions creating multiple warning messages are often not detrimental to overall communications. They are only an indication that action is required by maintenance personnel to preserve plant performance.
Main features and highlights are listed below and indicate where they are applied - Commissioning (C), Monitoring (M) or Troubleshooting (T):
The ADM monitors the following parameters:
Due to the Diagnostic Manager signal level, noise and jitter can easily be identified.
The signal level is the voltage of the communications signal that a device transmits on the fieldbus cable. It is generated through a current change created by the device. This current change is then “translated” into the voltage change detectable by all fieldbus participants through the terminators located at each end of the fieldbus trunk.
Noise is an unwanted disturbance that is induced in the fieldbus cable from outside sources, e.g., through EMI.
Jitter is the deviation of the ideal zero crossing point of the transmitted signal curve during the nominal bit duration, measured with respect to the previous zero crossing point. This is an extremely sensitive measurement.
Any hardware connected to the fieldbus segment influences the electrical attributes of the segment. Each change in connected hardware causes a change in electrical parameters, which in turn changes the signal form and typically increases jitter:
In reality, a system is able to run with higher jitter levels but with reduced immunity against EMI such as noise. The amount of jitter is only dependent on the quality of the connected components.