To meet the various requirements, SafetyNET p supports two types of communications. The SafetyNET p Real-Time Frame Line (RTFL) format is optimized for extremely fast communication in highly dynamic applications. The Real-Time Frame Network (RTFN) format provides the ability to communicate via any Ethernet network. Both versions are compatible with each other and may be used separately or together.
In SafetyNET p, individual devices are connected in a linear cable structure. If a branch is required, it can be created using a normal switch. It is possible to have a standard industrial linear topology and a much more flexible tree or star topology.
Standard Ethernet devices can either be connected to the last subscriber on a SafetyNET p line or at any point via a switch. Standard devices such as laptops, printers, or video cameras may use any type of Ethernet frame. These include all the familiar PC utilities such as e-mail, FTP, Internet, video, and other Industrial Ethernet versions, provided these use Ethernet frames.
Dynamic detection and network structure management is provided explicitly in SafetyNET p. This enables service devices to be connected if required, but is also an absolute essential for mobile applications or tool change.
The SafetyNET p communications structure does not use a centralized Programmable Logic Controller (PLC). Peer-to-peer data transfer enables decentralized data processing. Complex plants, therefore, can have a modular structure and flexible individual modules in terms of dimensioning, planning, and commissioning.
A beneficial side effect of decentralized processing can be seen in reaction to local events, which in most cases is considerably quicker.
For optimum investment protection, existing fieldbus installations can communicate with other plant sections via SafetyNET p using proxies. That way, SafetyNET p can have access to data from the relevant fieldbus.
Both safety and real-time functions use SafetyNET p’s real-time capability. When using SafetyNET p RTFL and the SafetyNET p protocol chip, a real-time scan time of 62.5 µs is supported. Devices without these high real-time requirements can use generic Ethernet interfaces in SafetyNET p RTFN. Used with the software driver for implementing the security protocol, this represents a flexible, cost-effective procedure.
Coexistence options
Using SafetyNET p for all automation communication utilities offers a simple integration method in which all automation devices communicate via a common network. Whereas scan times of up to 62.5 µs can be achieved in individual sectors, slower speeds may also be used at the same time. This can be adjusted to suit individual requirements of the devices and the application. Extremely fast scan times and the possibility of synchronized distributed clocks allow for synchronization of drives and even communication within the internal sensor-actuator closed-loop control system.
The topology or device layout can be adapted to suit the requirements of respective production cells. Even devices only temporarily connected to the network may be used as well as varying subscriber structures. While the former is primarily required for servicing or installation, the latter occurs in applications with mobile devices or on tool-changing equipment.
The combination of real-time capability and production control is rounded off on SafetyNET p by the facility for safe communication. Both real-time communication and safe communication can take place beyond the boundaries of a production cell via a standard Ethernet TCP/IP network. By using switches, communication between devices such as laptops, printers, or cameras can take place as cross traffic.
SafetyNET p mechanisms guarantee these utilities can coexist on the same line without adversely affecting real-time capability or safety. SafetyBUS p users can intelligently combine the system’s known capabilities with SafetyNET p’s real-time or TCP/IP capabilities, thus protecting existing investments. In practical terms, SafetyBUS p is connected either via a special device (proxy) or a safety PLC with interfaces to both networks.
This feature allows all existing SafetyBUS p devices to be used within SafetyNET p networks now and in the future. Where a specific Industrial Ethernet system such as PROFINET or EtherNet/IP has already been defined for the standard section, it is absolutely vital for SafetyNET p to have a high coexistence capability.
In such a case, the specific Industrial Ethernet can communicate within one and the same network, which guarantees the user’s individual preference for a specific Industrial Ethernet. At the same time, the user can employ SafetyNET p and benefit from its advantages, including performance features such as speed, security, openness, and extremely flexible topologies.
Users, system integrators, and engineers can therefore meet requirements arising from nontechnical or organizational reasons. At the same time, they can benefit from SafetyNET p’s unique performance.
(cont. part three)
