Industrial fieldbus solutions Few applications of fieldbus automation are in airports and cruise terminals, shopping centres, hotels, schools and other commercial building
A complex automated industrial system — such as manufacturing assembly line — usually needs a distributed control system—an organized hierarchy of controller systems—to function.
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Fieldbus is the name of a family of industrial computer network protocols used for real-time distributed control
A complex automated industrial system — such as manufacturing assembly line — usually needs a distributed control system—an organized hierarchy of controller systems—to function. In this hierarchy, there is usually a Human Machine Interface (HMI) at the top, where an operator can monitor or operate the system. This is typically linked to a middle layer of programmable logic controllers (PLC) via a non-time-critical communications system (e.g. Ethernet). At the bottom of the control chain is the fieldbus that links the PLCs to the components that actually do the work, such as sensors, actuators, electric motors, console lights, switches, valves and contactors.
Fieldbus can be used for systems which must meet safety-relevant standards like IEC 61508 or EN 954-1. Depending on the actual protocol, fieldbus can provide measures like counters, CRCs, echo, timeout, unique sender and receiver IDs or cross check. Ethernet/IP and SERCOS III both use the CIP Safety protocol, Ethernet Powerlink uses openSAFETY, while FOUNDATION Fieldbus and Profibus (PROFIsafe) can address SIL 2 and SIL 3 process safety applications.
Fieldbus control system
In many applications, the Dupline® signals need to be controlled and monitored from a central PLC or PC. To accommodate easy and flexible interfacing there is a number of products available for interfacing via serial ports (RS232 or RS485) or via standard Fieldbus connections (Profibus-DP and DeviceNet).
Dupline® is commonly used as a Remote I/O system for PLCs and PCs with SCADA software, typically in applications where the unique Dupline® features matches the system requirements. In order to facilitate easy and cost-effective interfacing to the control level, a number of serial RS232/RS485 interfaces and fieldbus gateways have been developed.
PLC interfacing using fieldbus gateways
Many PLCs are available with fieldbus communication integrated. This is the case for major PLC brands like Siemens using Profibus-DP and Allen- Bradley using Devicenet. Gateways, that translate the Dupline® data into the fieldbus protocol and vice versa, are available for both of these leading fieldbus systems. The fieldbus communication ports on PLCs are useful for Dupline® interfacing, because they offer a standardized method of automatic data-transfer between the PLC (master) and the Dupline® fieldbus gateways (slaves). The PLC programmer is relieved of the task of working with serial protocols, because the PLC operating system automatically takes care of the communication. Another advantage is the possibility to connect several gateways to the same PLC fieldbus port. This enables design of systems with thousands of I/O points, but still with an updating time of less than one Dupline® cycle.
Fieldbus can be used for systems which must meet safety-relevant standards
Depending on the actual protocol, fieldbus can provide measures like counters, CRCs, echo, timeout, unique sender and receiver IDs or cross check.
Safety Instrumented Functions are in compliance with International Electrotechnical Commission (IEC) 61508 standard (functional safety of electrical/electronic/programmable electronic safety-related systems) requirements up to, and including, Safety Integrity Level 3 (SIL 3)