PROFIBUS DP and PROFINET

PROFIBUS DP

In This chapter we discuss about Siemens (PROFIBUS DP, Actuators Sensors Communication , Industrial Ethernet , PROFINET , PROFINET Device Types , PROFINET Profiles ) devices overview.

Chapter -17

CPU 1516-3 PN/DP  Communication module CM 1542-5

• A Fieldbus is an industrial network used for distributed control and the most popular Fieldbus is PROFIBUS.

• The two most common forms of PROFIBUS are PROFIBUS DP for Factory Automation and PROFIBUS PA for Process Automation.

• Both types of PROFIBUS are open standards of PROFIBUS & PROFINET International Some Siemens PLC CPU models have one or more built-in PROFIBUS DP ports.

• Siemens PLC'S also allow a communication module to be added for PROFIBUS DP communication.

• PROFIBUS is a master-slave system.

• A slave device communicates only when requested to do so by its master device.

• A PROFIBUS master can control up to 125 slaves connected to the master in a linear topology.

• PROFIBUS uses copper or fiber optic cables but infrared communication is also supported.

• PROFIBUS has a maximum data rate of 12 Mbps PROFIBUS has two classes of master devices.

• Most communication is handled by a class 1 master which is often a PLC A class 1 master controls all communication with its slaves.

• Most of this communication is handled through a cyclic polling process.

• A class 2 master is used for configuration, maintenance, and diagnostics and can communicate with class 1 masters and their slaves.

Actuator Sensor Communication

• AS-Interface (AS-I) is an open low-cost network endorsed by the AS International Association that simplifies the interconnection of actuators and sensors with controllers.

• AS-I replaces the complex wiring and proprietary interfaces often used for this interconnection with only two wires which transfer both data and power.

• AS-I is most often used where actuators and sensors are distributed throughout a machine or facility.

• In an AS-I network a master communicates with up to 62 slaves through a cyclic polling process.

• The master is often a PLC with a communication module.

• The master slaves and 30 V DC power supply are interconnected by the two-wire AS-I cable.

• I/O-Link is another actuator-sensor communication system.

• I/O-Link is an open communication standard developed by the I/O Link research group of PROFIBUS & PROFINET.

• International in response to the need for a simple low-cost way to allow actuator and sensor communication in a concentrated area such as for a control panel or individual machine.
  
  
• I/O Link is a point-to-point system not a field bus.

• It uses a three-wire cable 24 V DC power supply and an I/O-Link master.

• Depending on the master up to 16 devices per master are allowed.

• The graphic shows two examples of I/O Link masters and some of the many I/O Link slave devices that can be used with Siemens PLC'S.
  

Industrial Ethernet

• Ethernet was developed in the 1970's to network office computers.

• As the use of computers increased in both the office and the factory the need for common communication approaches lead to the development of Industrial Ethernet.

• which uses industrial switches to provide the performance and reliability needed for high-speed factory networks.

• An Industrial Ethernet switch is an active network component that allows multiple devices to communicate simultaneously at high speeds.

• Industrial Ethernet allows communication speeds up to 100 Mbps with full-duplex operation which means that network devices can simultaneously send and receive data.

• The Siemens SIMATIC NET product family includes SCALANCE Industrial Ethernet switches designed to fit varied requirements from localized to plant-wide networks.

• Siemens also offers an extensive array of devices for interconnecting network components via Twisted-Pair Cable, Optical Fiber, or Wireless signals.

• For example Siemens Fast Connect system includes cables and connectors designed for demanding factory applications and assembly tools designed to speed installation.

PROFINET

• PROFINET is the open Industrial Ethernet standard of PROFIBUS & PROFINET International and the leading Industrial Ethernet standard.

• PROFINET I/O the most widely-used form of PROFINET extends the benefits of standardized Ethernet communication to distributed field devices by simultaneously handling three (3) communication performance levels.

• Non-time-critical communication uses standard information technology protocols.

• Real-time (RT) communication works well for most control tasks.

• Isochronous real-time (IRT) communication handles the most time-sensitive tasks such as motion control applications.

• Because PROFINET is an open standard it allows field devices from many suppliers to be easily connected to the network.

• PROFINET also protects investments in existing networks by simplifying their integration into a factory wide network.

• The figure shows an example of a few of the system types that can be easily integrated into the network.

• In a PROFINET system the number of devices is not restricted.

• PROFINET uses copper or fiber optic cables but also supports Industrial Wireless Local Area Network (IWLAN) communications.

PROFINET Device Types 

• Devices on a PROFINET Network are connected through a switch.

• Siemens offers a variety of stand-alone network switches and as shown in the graphic many Siemens control devices have a built-in switch with one or more PROFINET ports.

• Devices with two ports simplify use of a linear topology or a combined topology that includes devices connected in a linear manner.

• The following PROFINET device types are : I/O Controller, I/O Device, I/O Supervisor, and Proxy

• A PROFINET system includes at least one I/O Controller with I/O Devices assigned to it.

• The I/O Controller is typically a PLC or other control system which configures the I/O Devices and exchanges data with them but does not control their communication.

• An I/O Device in this context is not a PLC input output device but a PROFINET- compatible electronic device that often also allows actuators and sensors to be connected.

• An I/O Supervisor which is often a programming device human machine interface or personal computer is used for commissioning, monitoring, and diagnostics.

• A Proxy is a device that connects a PROFINET network to a fieldbus such as PROFIBUS.

• Because the proxy maps the sub-network to PROFINET all the devices of the sub-network are available for PROFINET These PROFINET device types have been part of the standard since its inception.

• Later innovations to PROFINET IO include the following device types

• Shared Device and I/O Device.

• The Shared Device capability allows two I/O Controllers to use the same I/O Device.

• This is accomplished easily by copying the configuration from one I/O controller to another.

• The benefits are reduced costs for Equipment, Engineering, Installation, and Maintenance.

• I/O Device is short for intelligent device.

• The central I/O Controller has direct access to the input/output image in the local I/O Controller so communication is simple and fast and no complex programming or additional communication hardware are required.

PROFINET Profiles

• PROFIBUS & PROFINET International (PI) has working groups with representatives from many companies including Siemens.

• These working groups specify configurations of PROFIBUS and PROFINET devices that meet special requirements.

• The specifications are published by Pl as profiles.

• Profiles are open and vendor- neutral allowing users to incorporate products from multiple suppliers into their systems without concern for interoperability.

• In addition to the PROFINET I/O profile which provides for the integration of distributed field devices via Industrial Ethernet examples of PI profiles are: PROFI Drive, PROFI Safe, and PROFl Energy

Profinet , Profidrive , Profisafe , Profienegry

• PROFI drive and PROFI safe were initially developed as PROFIBUS profiles and later extended to include PROFINET PROFIl energy is a PROFINET profile.

• The PROFIdrive profile allows users and OEM'S to design machines and processes with drives from multiple suppliers communicating PROFIBUS or PROFINET PROFIsafe is an integrated safety technology applicable for both discrete manufacturing and process automation which permits the transmission of standard and safety-related data on a single bus cable.

• The PROFl energy profile enables the design of systems with controllers such as PLC'S that can signal equipment referred to as energy consuming units (ECUS) to begin a sleep mode at the start of a planned pause or unplanned work stoppage.

• Software in each ECU determines how the sleep mode is implemented.

• When the sleep mode is over the controllers signal the ECUS to resume operation.

• The use of PROFl energy configurations enables substantial energy savings without a reduction in productivity.

Chapter 18 

we will discuss about (Siemens PLC Programming Concepts ) Topics.

SIEMENS PLC Class for Beginners

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