All about AS-Interface An overview for new and experienced users as-interface Basics Design Practice Utility Get a Great Connection
The “eyes and ears“ of production When you automate a process, sensors and actuators are always required. Whether it be in a logistics center, where light barriers check the position of a package on a conveyor belt, in a beverage bottling plant where the liquid level is checked, or in a steel mill where beams have to be cut at a precise position. Sensors – the eyes and ears of process control – are everywhere.
Contents 1. 2. 3. 4. AS-Interface – Just another bus system? Field bus technology – why “go by bus”? Industrial communication Supervisory level Field or process control level Actuator/sensor level 5.
1. AS-Interface with which process and local machine, digital and analogue signals can be transmitted in binary form has been around since 1994. AS-Interface is also the universal interface between the higher control level and simple binary actuators and sensors. In the past each individual sensor had to be wired to the controller (parallel wiring). Today, the sensors and actuators are simply connected to each other and to the control via one cable – the AS-Interface cable.
Previous costs: 100 % Conventional 26.6 % AS interface Control I/O distribution assembly Cables I/O cabling Cable assembly I/O cabling assembly I/O distribution material Sensors due to savings in configuration, commissioning, and flexibility of system expansion Courtesy of: TU München Prof. Reinhard Prof. Milberg A comparison of the costs between conventional installation technology and AS-Interface using the example of a milling machine.
To help you understand the tasks of ASInterface and its position in the control hierarchy in industrial communication, here is a short explanation of the basic properties of the various levels. Supervisory level At the highest level, the supervisory level, the computers on the management level in a factory, or sometimes even in more than one factory, are inter- Host computer Supervisory level Industrial Ethernet Programmable controllers e.g.
networked, or a host computer controls production as a whole using the computers as slaves. The data volume is in the megabyte range and transmission of the data does not need to be in real time. The transmission medium might be Ethernet. Field or process control level At the field and process level, PROFIBUS® (process field bus) has become standard. With a transmission rate of up to 12 Mbits/s in its DP version, it is ideal for the high demands of automation technology.
AS-Interface – The perfect solution 2. Before the task of developing a bus system, for the lowest field level which was both open and manufacturer independent (just like Ethernet or PROFIBUS) could be undertaken, a simple problem had to be solved: Components supplied by a wide range of different manufacturers which all had to be connected to the same bus system were not necessarily able to communicate smoothly with one another and with the system.
With IP67, AS-Interface is well equipped to deal with dust, humidity, and extreme temperatures. Master Power supply Slave Slave Slave AS-Interface cable The technical result is remarkable. ASInterface fulfils all the requirements just about perfectly, in field use (IP65/IP67), in the control cabinet (IP20), and in temperature ranges from -25 °C to +85 °C. Single master system AS-Interface was conceived as a single master system with cyclic polling.
Small volumes of data AS-Interface has been optimised for volumes of data that correspond precisely to the requirements of the lowest field level. The structure and length of the data frame is fixed. Up to four useable Input bits and four useable Output bits are exchanged between a slave and the master in any one cycle. Real-time requirements The maximum cycle time, i.e. the time that a master takes until a node is polled again is a maximum of 5 ms for a fully utilised system with up to 31 standard slaves.
Network topology The AS-Interface network can be configured like any conventional electrical installation. Due to the robust functioning principle behind the structure, any network topology can be used. Tree, bus, or star topologies are possible. More AS-Interface with new Specification In an AS-Interface system configured and designed according to Specification 2.1, up to 62 A/B slaves can be con- nected. The slaves have the capability of having 4 input and 3 output addresses maximum (i.e.
3. AS-Interface – Its main components Master The AS-Interface master provides the link to the higher-level controller. It organises data transmission along the ASInterface cable automatically, making the signals of the sensors and actuators available to higher-level bus systems, e.g. PROFIBUS, at an interface. See also Links.
Up to four binary sensors and actuators can be connected to a standard ASInterface module. Decentralised startup of a DC motor: No problem with the DC starter module and AS-Interface Slave The most important component of the whole AS-Interface system is so small that would fit comfortably on a fingernail. But without it, AS-Interface would never have become as important as it is today. We’re talking about the AS-Interface slave chip.
Cables The yellow profiled cable has become synonymous with AS-Interface. It has a geometrically defined cross-section and simultaneously transmits data and auxiliary power to the sensors. Additional auxiliary power is required for the actuators (aux. voltage, e.g. 24 V DC). Different coloured profiled cables have been specified utilising the same installation technology. A black profiled cable is therefore used for 24 V DC auxiliary voltages.
Power supply units AS-Interface power supply units are a necessity of an AS-Interface network. They produce a controlled DC voltage of 30 V DC with a high degree of stability and low residual ripple and work on the principle of a primary switched-mode regulator. Data and power are always transmitted simultaneously via the AS-Interface AS-Interface power supply unit twisted-pair cable.
Additional components for expansion with … The AS-Interface functions without any problem with standard components up to a length of 500 m – without repeaters or extenders up to 100 m. … repeaters When using repeaters, up to two repeaters can be connected in series, on which all components can be distributed to the segments in any way.
… extenders The AS-Interface cable can also be lengthened by 100 m using extenders, in which case no slaves must be used in the first segment. Extenders are only recommended for covering large distances, say, between the control cabinet and the plant. A total cable length of up to 500 m with standard components: two lines with a star network topology run in opposite directions from the centrally located master each to a repeater.
AS-Interface – Simple connection 4. Insulation piercing technology Profiled cables can be connected to the slave interfaces at any location easily and safely. This has been made possible by insulation piercing. How it’s done: Contact needles pierce through the cable insulation and make secure contact with the copper conductor.
AS-Interface in practice 5. AS-Interface has not only become a standard industrial interface for connecting simple binary devices. The claim of “easy entry without special bus know-how” is not exaggerated. On the contrary: The superiority of AS-Interface lies in its simplicity. Beginner’s checklist Here is a checklist of 10 points for the beginner, to make entry into the world of AS-Interface even easier: 1.
6. When are the modules mounted? Only when points 4 and 5 have been dealt with. Cables can be routed in any way. 7. How is it all configured? The configuration is simply read in by entering the AS-Interface profile for each slave in the master. This usually happens automatically but can be done manually in the controller software. 8. Are the slaves detected? First you must check whether the master has recognised all its slaves.
Configuring As far as AS-Interface is concerned, configuring means nothing more than drawing up a list of the configured slaves and then storing it in the master. Configuring is usually performed at the master, which means that the master automatically reads in the network configuration. (The user can also make settings for special applications at the PLC).
Parameterisation Usually, slaves are not parameterised. Only intelligent slaves with required options are parameterised. The data sheet of the slave in question defines whether it has to be parameterised and what function the parameters have. Whereas the address of a slave never changes in normal operation, the parameters are very likely to change. We therefore make the distinction between variable and fixed parameters. Fixed parameters are defined only once during configuration.
Ten valuable tips on assembly The following 10 tips should be followed to make sure nothing goes wrong during assembly: Tip 1 – Power supply unit On no account must AS-Interface be grounded! Never use a normal power supply unit only AS-Interface power supply units (PELV) with integrated data de- coupling and connect “ground (GND)” with system ground.
Tip 5 – Routing of the cable When laying the AS-Interface cable please note the following: • Always use the yellow profiled AS-Interface cable where possible, brown for “+” and blue for “-”. • Even whilst communication along the AS-Interface cable offers a high degree of EMC immunity, it should still be routed away from power cables, even in the control cabinet! • Every AS-Interface line requires its own cable. AS-Interface cables must not be laid together with others in a bus cable.
What to do if something goes wrong Errors can occur even in the best systems. In AS-Interface too, there are error patterns that are usually easy to detect and just as easy to eliminate. The only error that AS-Interface cannot recognise is the failure of a binary sensor or actuator integrated in a module. A defective slave can simply be replaced by a new slave. An AS-Interface cable break will of course result in the failure of slaves.
6. AS-Interface applications Three applications have been chosen to show you how flexible AS-Interface is: Whether empty bottles of different types are distributed to the correct stations, overhead conveyor motors are controlled in a car engine plant, or a highspeed laser-cutting machine is completely networked by using AS-Interface: Everywhere, AS-Interface shows just how flexible and efficient it is.
Germany’s largest bottle sorting plant which covers a surface of 60 x 30m on three floors. A total of 8 ASInterface lines all with a maximum cable length of 100 m provide full I/0 cabling. The company Dr. Wiewelhove in Telgte, Westphalia, has designed and built what is now the largest empty bottle sorting plant in Germany for Bier Schneider in Dortmund.
Round she goes Material handling with AS-Interface at the VW engine plant in Saxony Germany Putting the load feeders, e.g. motor starters, into the field means transferring the advantages of field bus communication to the power side. Switching and protection devices are mounted in close vicinity to the motor, so that the motor cable itself is very short. The distributed motor starters draw the energy they require from a single “power bus”.
2,200 engines are checked, conveyed, and stopped daily. The stoppers are controlled by ASInterface compact starters. by AS-Interface. Only a few central control elements, e.g. for in- feed and safety technology, now remain in the control box. Switches controlled by barcode readers are responsible for the controlled passage of the engines through the individual production sections of the circular conveying system.
At the speed of light AS-Interface in operation with laser-cutting machines The HSL2502 high-speed laser-cutting machine is the new showcase machine of Trumpf based in Neukirch, Saxony, Germany. The machine was networked completely using AS-Interface at the field level, including the auxiliary devices such as the hydraulic unit, extraction, closed-circuit cooling unit, and the infeed system.
Reduced stocking of spare parts thanks to standardized components. It is possible to dispense with the typical terminal boxes and cable and connector assemblies for digital inputs and outputs and for selected analog signals. special safety bus is not required. By only having one cable for the machine control, large wiring looms are no longer a part of the features associated with such high dynamic machines.
7. AS-Interface and safety No risks must be taken when it comes to the safety relevant components of manufacturing automation e.g. emergency stop switches, light barriers, protective door contacts, safety light grids etc. Uninterrupted functional reliability of all the sensors and actuators with reliable feedback signals in the millisecond range have top priority when it comes to protecting personnel and equipment from injury and damage.
Example of group formation of safe signals in the AS-Interface: The 3 EMERG. OFF buttons in the example are implemented in such a way that they can be connected directly to the yellow AS-Interface cable. In that way, they conform to category 4 to EN 954-1. The safe module has 2 safe inputs. Standard sensors, e.g. limit switches, etc. to category 2 (2 inputs) or category 4 (1 dual-channel input) can be connected. The safe module and EMERG: OFF 1 act on safety monitor 1. For example, if EMERG.
8. AS-Interface and Siemens From Siemens you can obtain all the components you require for installation, operation, and maintenance of an AS-Interface network. The offer is complete and adapted to the user’s requirements: From a simple standalone network to a highly specialised solution with AS-Interface working in conjunction with other bus and control systems in many different ways, all components are offered. Even integration into decentralised drive solutions, e.g.
SIMATIC NET AS-Interface master SIMATIC C7-621 ASi SIMATIC ET 200X Integrated interface (Specification V2.01) CP 142-2 Integrated motor starter SIMATIC S7-300 CP 343-2 SIMATIC S7-200 CP 243-2 The range of Siemens AS-Interface components is too extensive to deal with adequately in this brochure. You can read about all products and technical data in the catalog “Components on the field bus” (low voltage field technology (NSK) and IK PI) that your Siemens contact stocks for you.
DP/AS-Interface link 20E The DP/AS-Interface link 20E connects PROFIBUS-DP with AS-Interface at transmission speeds up to 12Mb. The link 20E is a PROFIBUS-DP slave and an integrated AS-Interface master in one housing that is IP20 rated. It is powered from the AS-Interface cable; so no additional 24v power supply is necessary for the system. CP 343-2 The CP 343-2 is the AS-Interface master for the SIMATIC S7-300 programmable controller and the ET 200M distributed I/O range of equipment.
CP 142-2 An AS-Interface master is available for the distributed I/O system for PROFIBUS networks ET 200X, too. The CP 142-2 communication processor is connected to the ET 200X module via a 12-way connector and uses its standard I/O range. No configuring is required for the AS-Interface network. Up to 31 slaves can be addressed by the CP 1422 (124 inputs and outputs).
Four different AS-Interface load feeder modules are available. Direct and reversing starters, as well as double direct starters and starter combinations for pole switchover can be wired with them. The feedback signals from the circuit-breakers and contactor(s) can be scanned at the inputs. The outputs are used for direct control of the contactor coils.
Compact modules The AS-Interface compact modules are part of a new generation of AS-Interface modules available with a high degree of protection. They combine digital, analogue, pneumatic, and 24 V DC motor starter modules in a single family. Two module sizes, the K45 (45 mm wide) and the K60 (60 mm wide) together meet all installation requirements. An installed module can be addressed via an integrated addressing socket. Degree of protection IP67 is met by locking the socket with an optional blanking cap.
K60R: The IP68 module for the AS-Interface The K60R module, with round cable connection and degree of protection IP68, is now available – and it supplements the K45/K60 series of compact modules with degree of protection IP65/67. The new design can be operated in environments which have high permanent levels of moisture. This results in many practical applications. • Use in especially moist ambient conditions, for example, in beverage filling systems, on machine tools and in the food and beverage industry.
PRODUCT OVERVIEW 24 V DC motor starter With the K60 AS-Interface 24 V DC motor starter for the lowest power range up to 70 watts, it is now possible to connect 24 V DC motors and the associated sensors to AS-Interface directly at the machine. Three different versions are available with the following capabilities. Direct starter (without brake and optional quick stop function), double direct starter (with brake and quick stop function), reversing starter (with brake and optional quick stop function).
Proximity switches with an integrated AS-Interface BERO proximity switches can be connected to the AS-Interface directly or via modules. Special inductive, optical and ultrasonic BERO proximity switches suitable for direct connection to the actuator sensor interface are also available. They feature an integrated AS-Interface chip and can supply information (e.g. filling level, coil failure) in addition to that supplied via the switching output.
The concept of “safety at work” permits integration of safety-related components such as emergency stop buttons, guard door switches, or safety light grids, to be connected directly into a standard or V2.1 AS-Interface network. These components are fully compatible with the standard AS-Interface components i.e. master, slaves, power supply unit, repeater, etc. according to EN 50295.
Protection monitoring and SIGUARD position switch Suitable for direct connection to the ASInterface network. There is a special interface module designed for this unit that can be installed on the thread of a position switch. The removes the need to conventionally wire the safety functions. Emergency stop button Through the standard AS-Interface with safety-related communication, it is now even possible to connect EMERG. STOP devices directly. This also applies to EMERG.
Addressing and diagnostic unit With the new device it is possible to address both the standard slaves with addresses 0 to 31 and the new slaves according to Specification 2.1 with addresses 0 to 31 A, B. In addition, the I/O and ID codes of the slaves can be displayed. Additional functions available are the ability to program the ID code 1, function check of the connected slaves, detection of the complete system, diagnostics, storage of configurations, and a PC gateway function.
Repeaters and extenders Repeaters extend the AS-Interface segment by 100 m to increase the networks flexibility in the design and implementation stages. The extender increases the distance between the master and the first AS-Interface segment containing AS-Interface slaves to max. 100 m. Note: it is not possible to install slaves between the extender and the master.
Contact If there are any further questions regarding AS-Interface made by Siemens, please contact our experts of the “Technical Assistance“: Phone: +49 91 31/7-4 38 33 Fax: +49 91 31/7-4 28 99 E-mail: nst.technical-assistance@siemens.com Internet: www.siemens.de/as-interface Imprint All about AS-Interface Editor Siemens Aktiengesellschaft Automation & Drives Group (A&D), Erlangen Responsible for the technical content B. Salzer, R.
Siemens AG Automation and Drives Low-Voltage Switchgear P.O. Box 32 40, D-91050 Erlangen www.siemens.com/as-inter face Subject to change without prior notice 04/02 | Order No. E20001-A150-P302-V1-7600 | Dispostelle 27614 | 21C7453 CPAS.52.2.05 WS 04023.
