One advantage of the fieldbus is that actually less than 2% of all installations present some faulty behavior. This means that 98% of installations are of good quality and only have to be verified. Therefore, an on site presence is not really required any more for commissioning. It is best to carry out installation and commissioning in separate steps.
Field instruments pre-parameterized in the test laboratory are all connected directly to the fieldbus. Measurement, documentation and commissioning have been combined into a single operational step. If at all necessary, fault finding can be carried out afterwards.
From the control station the person carrying out the commissioning executes all the necessary tasks using the Advanced Diagnostic Module. Measurements and logging of the tasks are easily carried out via menus and queries. The complete documentation is generated automatically and provided optionally in electronic format or as printout. The process ensures that:
- The installation complies with the requirements of the IEC 61158-2 standard
- Every field device meets the requirements of the selected field bus standard
In addition, the power reserve of each fieldbus segment is calculated. The procedure can then look as follows:
- Connect all segments and field instrumentation as well as the field bus power supply
- Visually check the shielding – The shielding has been neatly attached and insulated at each field device
- Switch on the fieldbus power supply and activate the control technology to actuate all field devices
- Carry out all measurements and store and document them using the Advanced Diagnostic Module
This brief test procedure saves commissioning time. Furthermore, a deep technical expert knowledge about the fieldbus is only required for checking the segments which failed the test. Nonetheless, the installation and commissioning tasks to be carried out under ever increasing time pressure are executed with high quality.
The commissioning is supported by dialogs: First the trunk is measured and the supply voltage and the load current is verified. A ground fault measurement is carried out for both wires ensuring proper balance and isolation. Then the communication signals of each field device are checked for strength, noise and jitter. Limit values for the online monitoring of the physical fieldbus structure are suggested and stored in the diagnostic module.
All this and more is made possible by the integration of the diagnostic module into the power supply without a single terminal necessary for the connection of measuring devices having to be touched. The wiring in the switch cabinet remains unaffected.