Profibus sniffing using the PC-independent Expert Transient

Delphin Technology AG: "Sniffing" in measurement technology is understood as the passive listening in on a bus system. Data is transmitted via a bus system can then be recorded with a sniffer. But because the sniffer is not an active participant, it doesn't influence the bus system.

The tried and tested Expert Transient device from Delphin Technology is equipped with two Profibus slave interfaces and has now been upgraded to include a Profibus sniffing feature.

The sniffer interface enables the device to listen in on an active Profibus. Profibus sniffing does not require amendments to the existing Profibus parameters – the device does not appear as a participant in the Profibus network and is therefore no influence on it.

This function makes the Expert Transient a perfect tool for fault detection and analysis in plant and machinery. Profibus sniffing can acquire PLC functions and procedures. Additional intervention is unnecessary. The Expert Transient's high-speed analog and digital inputs can acquire – in synchronization with the PLC data – peripheral signals such as pressures, temperatures, flows, vibrations and the status of relays and contactors. An internal data memory plus a range of pre-processing features enables the device to operate fully independently from a PC and is highly suited for recording sporadically occurring errors.

Typical applications using Expert Transient and the sniffer function

• Fault diagnostics on PLC-based plant and machinery without accessing the controller
• Fault detection on plastic injection molding machine
• Long-term recording of plant and process data  
• High-speed data acquisition at test stands
• Data acquisition on drives and frequency converters
• Mobile measurement case for PC-independent fault analysis
• Fast and simple linking of plant and machinery to control systems
• Fault analysis on gas chargers, turbines and compressors
• PLC data logger

Fault analysis on drive systems and conveyor belts

Fault detection in large facilities often require the synchronized acquisition of measurement data and PLC information from different locations. Expert Transient enables high-speed and synchronized data acquisition from signals on frequency converters and drive systems as well as the information from their PLC systems. The data is recorded locally within the device. Triggers can then be configured to record faults along with their pre and post histories. For plant spread over wide areas which require multiple devices for fault analysis, synchronization takes place using a GPS clock. The data in the devices can be accessed using a network or USB stick and evaluated using analysis functions from the ProfiSignal software. ProfiSignal combines data from different devices to enable precise fault analysis according to the cause-and-effect principle.