Controlling the central nervous system:

About bus monitors

If PLCs are regarded as the brain of modern industrial plants, bus systems are the central nervous system: while the necessary control, regulation or computing tasks are processed in the controllers, data is transferred cyclically between the controllers and the peripherals via field and drive buses. Especially in times of increasing complexity and data volumes, industrial network systems are becoming more and more important: only if users understand and master the technical interrelationships of their system can they optimize efficiency, availability and product quality in the long term.

With the iba system, which offers perfectly adjusted hardware and software components for acquiring, recording, analyzing and processing measurement data, all relevant plant and process data from a wide range of signal sources and systems can be acquired and recorded. If data is to be recorded deterministically and unadulterated, the focus is on communication between controllers and devices on the bus network: a direct insight into the data sent here provides users with an undistorted picture of the processes and sequences of the system - there is hardly any other place where data can be collected more directly. The integration of a bus monitor, such as the ibaBM-PN for PROFINET or ibaBM-DP for PROFIBUS networks, into the topology can therefore be a game changer and thus a milestone in a company's digitalization strategy. It is easily integrated into the network and provides data that is collected synchronously from the network.

Different standards as a major obstacle

A major challenge here is the heterogeneous landscape of bus technologies, as different standards have become established in the industrial environment - PROFINET, EtherNet/IP, EtherCAT®, PROFIBUS or CAN/CANopen are just some of the technologies used. This is where the iba system offers a solution: thanks to its excellent connectivity to different automation systems and bus technologies, it can be connected to all common fieldbus systems. In this way, an iba data acquisition system can be integrated into most existing networks using the iba bus monitors. The data and signals monitored by the bus monitor can thus be recorded and visualized by data acquisition software (ibaPDA) and then made available to users.  

The requirement determines the operating mode

The bus monitor can be operated in different ways: In sniffer mode (=listening mode), the values transmitted on the bus are read and recorded as signals. In this case, no changes need to be made to the project configuration. In active mode, as a so-called active bus participant, the bus monitor can actively receive values sent to it by the PLC. The bus monitor is specifically addressed by the controller and supplied with any data. The mode in which the bus monitor is operated in an individual case always depends on the respective application.

Operation as a sniffer

In sniffer mode, the bus monitor listens in on the bus wire and can therefore record all data transmitted on the bus without interference. Listening in on the bus line does not affect the actual data transfer on the fieldbus in any way. The data is recorded in this way without distortion - at the original speed and sequence. This enables an explorative analysis of the communication between the controller and the bus device. The iba bus monitor only needs to be connected in the network; it is not necessary to change the existing configuration of the controller. Within a PROFINET system, for example, the corresponding ibaBM-PN bus monitor is integrated between the controller and the respective devices. The connection is made via the TAP interface (Test Access Point) of the device, so adding the bus monitor does not create an additional point of failure, as communication between the controller and the PN devices is not interrupted even if the ibaBM-PN fails.

Operation as an active participant

As an active participant, the bus monitor is directly addressed by the PLC and can receive all values actively sent to it. This means that all the internal data of a control system can be recorded without having to connect it to an additional analog or digital IO terminal. In this case, the bus monitor is connected synchronously to the fieldbus system in order to receive deterministic data. The data to be sent to the bus monitor must be configured within a PLC. For the bus monitors ibaBM-DP (PROFIBUS), ibaBM-eCAT (EtherCAT®) and ibaBM-PN (PROFINET), the request method can be used for convenient measurement: The desired measured values are selected in ibaPDA via their symbolic name and are then transmitted cyclically. This requires the one-off integration of provided function blocks in the control system. A major advantage of this is that even system operators who have no programming experience can easily record the required data. The ibaBM-PN bus monitor, for example, has two independent, internal PROFINET devices that can be supplied with specific data and individually configured by PROFINET controllers. A bus monitor can therefore communicate with up to eight PN controllers, allowing integration into line or star structures as well as connection to two independent PROFINET strands. The devices can also be used to send data from ibaPDA to a controller via PROFINET. For example, certain signal values can be monitored and a warning message issued or other events signaled if a limit value is exceeded.

Diagnostic function

In addition to the two operating modes, iba bus monitors offer the option of collecting information on the status of the fieldbus and the respective devices and displaying it in ibaPDA. Within a PROFIBUS network, for example, the operating states of the different communication participants are displayed in color and the cycle time, baud rate or number of devices of a bus system are displayed. In this way, bus errors can be detected quickly, which has a positive effect on the availability of the fieldbus systems and maintenance costs.

Integration into the iba system

The configuration of the signals to be recorded is done conveniently in the I/O Manager of ibaPDA: With the help of automatic detection, the connected devices are detected in ibaPDA and displayed in the I/O Manager. The required settings can be made quickly and easily directly in the user interface and saved in the devices. Another advantage of the iba system is that the data recordings of the bus monitors can be displayed synchronously with other measurement signals - for example from interfaces - in ibaPDA. This creates a synchronous and clear database despite different standards or data sources.

Conclusion

Bus monitors such as ibaBM-PN from iba AG are an important component in the digitalization strategy of industrial plants. Whether as sniffers or active bus devices, they can be used to deterministically record data on the bus network and provide a clear overview of complex correlations by integrating them into the ibaPDA data acquisition software. For plant operators, this can be a major step towards a better overview of automation and production processes and therefore more sustainable or economical operation.