Looking at the speed, the network works at 9. It is dedicated to field applications, where communication between the measuring instruments and the control system is required.
Its physical network structure complies with IEC and the data rate on the network is At the time of development, Normally, there are fewer devices on an intrinsically safe bus when compared to a conventional network, but this depends on several factors that determine the optimal number of devices for each.
These are, for instance, instrument consumption current, bus length, cable type, etc. You can already find many manufacturers with field instruments using a native Ethernet-based protocol. Another advantage regarding its implementation, is that this type of protocol is easy to implement because it uses a well-known model with a low infrastructure cost. The standard allows the network to be built up in many different ways, for instance a ring, line, tree or star etc.
Due to its high-speed operation, it has a response time of less than 1 millisecond. When we talk about PROFIBUS, we are talking about a traditional and well-known digital communication protocol that has been implemented in different industries and applications.
This protocol is based on serial communication and has brought a lot of benefits to the industry. I really believe the organization is doing a great job of trying to decrease the gap on field protocol knowledge in different industries. I was part of the organization when I was working in Brazil, and we used to have large events to talk about the technology and bring knowledge to the end-users.
Profibus was designed in the s to meet all industrial communication needs for both factory and process automation Figure 1. One way of visualizing how these terms fit together is to think of Profibus as a book with many chapters. In addition, there would be a second book by the same authors called Profinet, with many chapters, including Profisafe and Profidrive. Profibus is also a master-slave type protocol like Modbus but with an additional token ring protocol to allow for multiple masters.
Each slave maintains a failsafe timer. If the master does not talk to it within a certain time limit, the slave goes into a safe state; the master must then go through the startup sequence again before further data exchange can occur. This, in combination with a watchdog timer in the master, ensures that all communication occurs every bus cycle with a certain time value. The general bus scan would happen as shown in Figure 2. Master A receives the token, which gives it control of the bus. It will then exchange data with each of its slaves, and when complete, pass on the token to the next master if there is one.
The requirement for detailed diagnostics from each slave is also built into the protocol. During normal data exchange, a slave can alert the master that it has diagnostics, which the master will then read during the next bus scan.
Profinet is built on the same principle as Profibus. However, in the case of Profibus, the Profibus specification does not simply refer to the existing RS specification. Instead, it extends the RS specification. The physical layer was tightened up to require only two wires, with speeds as fast as 12 megabits per second. In addition to cyclical communication for the fast exchange of input and output data between the master and slaves at regular intervals, need-based data can also be transmitted using PROFIBUS, e.
A master has the initiative, accessing the data of a slave in read or write mode acyclically. A crucial part of the acyclical data exchange process is the writing or reading of device parameters at the behest of the master. These device parameters can be used by a centralized operator tool to configure a field device, thereby adapting it to the specific task it has been charged with performing in the technical process.
Version DP-V0: Provides the essential functions of the communication protocol. It includes cyclical communication and device-, module- and channel-specific diagnostics for quick fault localization. These include features for communication between slaves, cycle synchronization, and time stamping.
Devices of this type are often integrated into a memory programmable controller or an automation station of the process control system. Devices of this type are usually part of an engineering station used for device configuration.
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