AS-i bus cuts cycle time in half for cleaning equipment manufacturer
BUS OF THE MONTH: AS-i Bus
By Control Engineering Staff
Atcor Corporation of San Jose, Calif. designs, engineers, and manufactures water-based cleaning systems for high-tech industries requiring ultra-clean parts or containers. Atcor's Ultra 6272 system, for example, uses a spray of deionized water, pressurized for the cleaning process. Pneumatic actuators open and close gates, as the objects to be cleaned are transported from zone to zone on a conveyor inside the cleaning chamber. These environmental characteristics affect the criteria for locating controllers, wiring specifications, and connector requirements.
Discrete Wiring Takes Time
..Spanning almost 30 feet, an Atcor system can involve hundreds of I/O connections. Using traditional wire bundles, assembly and wiring for Atcor's larger cleaning systems normally required from five to seven months manufacturing time to complete, not counting the wiring required at the customer site. Three of those months were typically devoted to wiring, testing, and debugging.
uring shipment, troubleshooting, or device failure. Once the system arrived at the customer site, the wiring was re-connected to the terminal block. This reassembly procedure multiplied chances of connection errors.
New Design Cuts Cable Costs
..Atcor looked at an Actuator-Sensor-Interface (AS-i) scheme instead of the traditional 'hard-wired' methodology in 1996. The two-wire, open protocol bus system is the result of a consortium of sensor manufacturers that sought to simplify wiring schemes. AS-i causes little change in field device level specifications because AS-i bus works with any PNP/24 V dc field component. The bus itself provides 24 V dc power for the input devices and communications from the field devices to the PLC.
es on the AS-i slave nodes. These slaves have front and back plates that screw together to sandwich the AS-i bus cable's rubberized sheath. Nodes can be added anywhere and be temporarily submerged according to IP67 standards. All standard AS-i nodes are supplied with gaskets on the coupling module to make each connection watertight; an inherent benefit of the system. Electrical connections are made by sharp teeth ('vampire' clips) inside the coupling module.
bus systems and devices are essentially immune to electromagnetic interference, a major concern within the semiconductor industry.
s. Data transmissionbetween the PLC and the AS-i nodes is trans-parent for the PLC's program, with regard todata input and output. The I/O data of the AS-i nodes are handled like hard-wired I/O data atthe PLC. Bus cycle time for 31 nodes is just five milliseconds. One master can control up to 248 binary elements when using bi-directional slaves. The master has LEDs that indicate node activity, and the nodes themselves have LEDs that indicate field device activity. These LEDs simplify troubleshooting.
to take less than a minute. Installation at the user site is now virtually trouble-free. Atcor has been able to chop its manufacturing cycle time from six months to only three for each of the Ultra 6272 units sold. Most of this time savings can be directly attributed to the AS-i bus network.
By Cherril Driggs, vice president Manufacturing and John Clarke, manager product engineering, Atcor Corp., San Jose, Calif.
AS-Interface: A brief overview
..The Actuator Sensor Interface (AS-i) was introduced to the European market in 1993 and the U.S. market in 1996 as a new interface for industrial communication at the lower-most level. AS-i connects first and binary sensors and actuators with the primary control level, e.g. the PLCs or PCs, via a bus line.With the idea of networking simple elements digitally and cost-effectively, AS-i covers the level beneath the fieldbus systems. As AS-i is very simple, it has the chance to substitute the cable tree.
etwork. Moreover, it does not require any programming of its parts by the user. Its main components comprise:
An AS-i chip in the sensor, actuator, or in a connecting module. The chip does not contain a processor, so it doesn't require software
A master, which automatically organizes the data exchange on the network
Electro-mechanical components; a novel, simple connection technique allows easy linkage of the components. Untwisted and unshielded two-wire cable is used for transmitting data and energy within the network
Source: AS-i: The Actuator-Sensor-Interface for Automation, Werner R. Kriesel and Otto W. Madelung, eds.
AS-i saves 20% on packaging machine overhaul
..BSN Emballage is France's second leading glass maker and one of the top European companies in that area of manufacturing. The company operates six factories in France; among these, the plant in Rheims has just fitted an AS-i bus to one of its packaging machines at the end of a production line.
ith a materials handling and packaging apparatus which loads bottles onto pallets automatically. The final operation consists of covering the individual pallets with a plastic film by means of a shrink-wrap packaging machine. It is one of these two machines that has been completely overhauled and equipped with the AS-i bus.
ice concerned with control and electrical technology, new works, and maintenance at the Rheims factory. 'Connecting the sensors and actuators to the PLC required the laying of an equivalent number of cables. As a consequence, we favored the AS-i bus solution rather than the traditional one based onparallel cables. This choice was made for technical as well as economic reasons.'
erall cost of overhauling the shrink-wrapping machine,' he said.' This gain has been achieved by a reduction in the number of connections and parts used, improved identification, simplicity in setting up, and reduced commissioning time. We are planning to extend the AS-i solution to larger machines,concluded Mr. Canonne.
Flat Cable Connectors
Riverdale, N.J.--A new series of flat cable connectors allow direct connection of sensors or actuators with an integral AS-i chip to flat cable. Contact of the new AS-i connectors is made automatically by screwing the two parts of the connection together. Connection to the end can be performed safely via a standardized M 12 x 1 connector. If the flat cable connector is connected directly to the AS-i device, the AS-i flat cable can be run parallel or rotated by 90°. HIRSCHMANN OF AMERICA INC.
PLCs Talk AS-i
Hants, England--The RPX line of PLCs is part of a new range of AS-i control products capable of controlling actuators and sensors on an AS-i bus and interfacing with other fieldbus protocols. The RPXs have 5 to 25 local digital I/O and an integral AS-i master providing up to 124 I/O. This is linked via the AS-i machine bus to machines, sensors, and actuators using just two wires which carry both the power supply and communications. The two types of modules are the ASIO20 for IP20 rated environments and the ASIO67 for IP67 conditions. Both modules are capable of accepting 4 I/O points. The complete AS-i network can then be linked directly to fieldbus networks via the RPX AS-i master and a suitable RPX comm slave unit. CROUZET
Module Links AS-i to Micro PLC
Alpharetta, Ga.--New communications options for the SIMATIC S7-200 microPLC include the CP242-2 AS-Interface master, a compact module that addresses and automatically recognizes up to 31 analog or discrete I/O of the low level bus system. Each slave can have a maximum of four inputs and four outputs, with a total update time of five msec. for the 31 slaves. The CP242-2 is connected directly to the PLC and can be further expanded with expansion I/O modules. SIEMENS E&A
Minneapolis, Minn.--Uprox proximity sensors include intelligent electronics for direct connection to AS-i device-level sensor and actuator networks. The new sensors meet all requirements for use with AS-i unshielded UTP (UnTwisted Pair) trunk line wire. These sensors claim to be able to detect all types of metals at the same sensing range while having up to three and a half times more range than comparable standard proximity sensors. The Uprox sensors are said to have an extremely fast switching frequency, several times that of their conventional counterparts. They are available in a wide variety of housing styles: cylindrical metal barrel styles and rectangular 'limit switch' style plastic housings and stainless steel, threaded barrel styles. TURCK INC.
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