x-series bar code reading - mettler toledo€¦ · asynchronous mode – requires the use of a...

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X-SeriesBar Code Reading

There are many uses for bar code scanners in product inspection applications. Scanners are used for product identification, inventory control, and more commonly automatic product changeover. What ever the application, Hi-Speed is now offering four (4) new bar code reading options tailored to accommodate a wide range of bar code reading applications. These new options provide a total solution and include the bar code scanner, mounting hardware, sensors, cables, and X-Series control configuration. These options are tested with the customer’s samples and functionality is verified prior to shipping the system to the end user.

How Bar Code Reading Works

In its simplest form, a bar code scanner projects a focused beam of laser light at a rotating mirror. The shape of the mirror causes the beam to sweep rapidly across a label containing some form of bar code. The laser reflection off the code is received by a photo diode inside the reader. An internal analog to digital (A/D) converter converts the analog reflection signal into a digital signal that can be read and interpreted by the scanner. The unique digital signal of the bar code can be associated with an individual product thus enabling further processing or actions.

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SolutionsJust as there are many types of bar codes there are also many types of bar code scanners. We have selected a range of scanners based upon the typical conditions found in Product Inspection where bar code reading may be used. There are four (4) new bar code reading options that range from short-range to long-range reading of multiple code types. Depending upon the size of the package, the type, size, and resolution of the bar code label, and the distance from the scanner to the bar code label we can provide solutions that will meet most of the applications you may encounter.

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DS2100N 3012mil

31020mil

22020mil 5 1,000 ACR-Lite ±45º

DS2400N 7514mil

60020mil

38020mil 8 1,000 ACR-Lite ±45º

DS4800A 2020mil

95020mil

70020mil 8 1,000 ACR™4 ±45º

DS6300 300any

1,40020mil

90020mil 8 1,200 ACR™4 ±55º

Qualified and Proven Bar Code ScannersOur bar code solutions utilize bar code scanners, sensors, and connectivity solutions provided by Datalogic. Datalogic is a long time standard preferred supplier of bar code reading solutions to METTLER TOLEDO and we have developed a strong partnership through installation and qualification of hundreds of solutions worldwide.

To ensure that you get the right bar code reader you need for your application and before we can provide a quote, we’ll need a completed Bar Code Product Application Checklist (PACL), which is similar to the RFQ. This checklist collects and organizes the important information that is the key to identifying the best possible solution for your application. The PACL collects and organizes critical application information such as code type, bar height, code length, and bar dimension along with package and transport information that ultimately becomes the basis for the solution.

Without the information provided on the PACL, it will be nearly impossible to recommend a bar code reading solution guaranteed to work for a particular application. This form must accompany the standard CheckweigherRFQ form when requesting a bar code reading quotation and will ensure the solution meets the requirements of the application. Also, when this completed form and samples of each code type included in the application is reviewed by Datalogic they will recommend the best possible solution for the application and also “guarantee the solution will function as specified”.

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Typical Application – Product Changeover Using Bar Code ScannerA bar code scanner connected via a serial cable to the X-Series checkweigher XRTC will provide the signal to change packages. The end user can define what code from the scanner string will be used to identify the package. The scanner code is part of the individual package file and up to 200 files can be stored in the individual package memory.

The system can be configured so that:

1). Every package passing over the scale must have a valid bar code*.

-or-

2). The last valid bar code read is also valid for the following packages.

*In case 1) a valid bar code must be received by the checkweigher controller before the packages reach the Weigh Light Barrier (WLB). If an invalid code, or no code, is received the packages will be rejected and classified as “Special” in the checkweigher statistics.

i NOTE: Statistics must be enabled for all packages.

Generally, when there is no associated package stored in the Product Memory corresponding to the code read by the bar code reader, the package will be rejected and classified as “Special” in the checkweigher statistics.

FeaturesManually entering bar code string information into the package file can be tedious and prone to operator error. With the X-Series bar code option the bar code scanner can be used to “read in” the bar code from a sample package into the product memory – a much more reliable method of entering the code string information.

There are also two (2) modes of operation; synchronous and asynchronous.

Synchronous mode – The WLB is used as the trigger for code evaluation. When the package that has been scanned breaks the WLB, the last bar code received from the scanner is evaluated.

Asynchronous mode – Requires the use of a separate input signal to start the code evaluation. With every low/high signal from the input sensor the latest bar code received from the scanner is evaluated and an package changeover occurs immediately. If the bar code scanner option will be used for “on the fly” changing of package files at the X-Series control, the asynchronous method with the additional sensor must be used.

Multi-Evaluation and Rapid Package ChangeoverIn the X-Series controls, product memory is stored within the IPC (Industrial PC). The number of packages that can be stored is dependent upon the control type. When product changeover by bar code scanner is enabled a smaller subset of the total package memory (8 products) are stored within a dedicated package file storage area in the XRTC (Extended Real Time Controller).When a bar code is scanned, the code information is first compared for a match with the eight (8) packages stored in the XRTC. If the code matches the current active package the package is processed normally. If the scanned code does not match the current active package, the XRTC package memory is polled for a possible match. If a match is found within packages in the XRTC a package changeover is triggered and the match becomes the new active package. Typical load time if the package is found in the XRTC is approximately 100ms.

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What Happens If A Bar Code Match Is Not Found?

If no match is found in the XRTC package memory the control will then search the regular package memory location in the IPC. If a match is found in the IPC package memory a package changeover is triggered and the match becomes the new active package, however this process may require up to 2 seconds to complete. The following explains why:

The ”load process” consists of several steps each of which requires processing time. First the correct file must be located in the IPC product memory. Then, that file is sent to the XRTC. Before the new file can be loaded into the XRTC product memory room has to be made for the new file. The XRTC purges the least used package file of the eight (8) stored files to make room for the new file. Once the new package file is available in the XRTC a package changeover is triggered.

The majority of package changeover by bar code applications process less than eight (8) products at a time so no additional processing time is required. For applications with greater than eight (8) packages or throughput rates greater than 60ppm some additional processing time may be necessary. The PACL will be reviewed for each application and if necessary recommendations offered for optimal performance.

To ensure that each code is read and processed correctly, there are monitoring and control settings within the bar code reader configuration, along with standard control Function Allocations the end user can apply, to ensure that every package is accounted for correctly.

• DuringtheloadprocessamessagecanbedisplayedinthemessagetrayoftheX-Seriesmainscreenindicatingto the Operator that the system is in the process of evaluating the signal and loading or performing a package changeover. The system can apply a Function Allocation to ensure any packages passing the WLB before a new load has occurred will be rejected.

• IfforsomereasontheXRTCisunabletoloadthepackagefilefromtheIPCtheendusercanusetheFunctionAllocation to stop the conveyor belt and post an error message on the checkweigher home screen.

• Ifthescannedbarcodedoesnotmatchanypackagecodestoredinthecheckweighermemory,nopackagechangeover will occur and the current package will remain active. The package with the unknown code, along with all subsequent packages with the same code, will pass the WLB and be weighed, but then will be rejected by the installed rejecter. The number of packages allowed to pass the WLB before subsequent packages are rejected is user configurable; the default setting is zero (0). Packages rejected in this manner will be counted as “Special” in the checkweigher statistics for better visibility. An error message can also be provided on the control screen indicating no match was found.

Parameter DescriptionWrong Coding No article memory can be allocated to the applied input signal. A large number of signals are available.

•Arejectormustalwaysbeassigned.•Oneofthefollowingmessagesdisplay:

“Multi: Wrong Code #”“Multi: Code OK”

Loading Fault The loading of an article has failed. When there is a communication error (XRTC <> IPC) the following message displays:

“Multi: No response of IPC”

Loading Delay An article memory (article setup) is being loaded. When the XRTC has to reload an article from the IPC the following message displays:

“Multi: Delay on package load”

Changeover Ready Article changeover (article setup changeover) is done.

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Glossary Of Terms

Aspect RatioThe ratio of symbol bar height to code length.

Auto Discrimination The ability of a bar code system to read and distinguish and correctly decode more than one symbology.

Background The spaces, quiet zones, and areas surrounding a printed symbol.

BarThe darker printed element of a bar code symbol

Bar CodeAn automatic identification technology which encodes information into an array of parallel rectangular bars and spaces.

Bar HeightThe bar dimension perpendicular to the bar width.

Bar Width The thickness of a bar measured from the edge closest to the symbol start character to the trailing edge of the same bar.

CharacterA single group of bars and spaces that represent an individual letter, number, punctuation, or other symbol.

ContrastThe difference in reflectance between a bar codes light and dark elements measured at a specific wavelength. Most scanners require a minimum contrast value as listed in their specifications.

DensityThe number of data characters that can be represented in a unit of measure – typically characters per inch.

Depth of FieldThe distance between the minimum and maximum plane in which a scanner is capable of reading and decoding symbols.

ElementIn a bar code symbol, a single bar or space.

Interleaved Bar CodeA bar code in which characters are paired together using bars to represent the first character and spaces to represent the second. For example; Interleaved 2 of 5.

LabelA label that carries a bar code symbol and is suitable to be affixed to an article or package.

MilOne thousandth of an inch (.001”).

Non-ReadIn a bar code system the absence of data at the scanner output after an attempted scan due to no code, scanner failure, or operator error.

Picket FenceA horizontal bar code or symbol presented such a manner that its overall length dimension is parallel to the horizon so that the bars represented look like a picket fence.

Print QualityThe measure of compliance of a bar code symbol to the requirements of dimensional tolerance, edge roughness, spots, voids, reflectance, PCS (Print Contrast), quiet zone, and encoding.

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METTLER TOLEDO Hi-Speed5 Barr Road, Ithaca, NY 14850 USAToll Free: 800-836-0836Tel: 607-257-6000Fax: 607-257-5232E-mail: [email protected]

Subject to technical modifications©METTLER TOLEDO Hi-Speed 2012Application Note 80A

www.mt.com/hi-speedFor more information

Quiet ZoneA clear space, containing no machine readable marks, which precedes the start character of a bar code symbol and follows the stop character.

Read Distance Maximum/MinimumThe maximum and minimum distance between the bar code and bar code reader that a particular scanner can read and decode symbol of a specific resolution.

ResolutionIn a bar code system, the narrowest element dimension that can be distinguished by a particular reading device. Typically described in Mils

ScannerAn electronic device that converts optical information into electronic signals.

SkewThe rotation of a bar code symbol about an axis parallel to the symbol’s length

SpaceThe lighter element of a bar code usually formed by the background between bars.

SpotThe undesirable presence of ink or dirt within a space.

Start/Stop CharacterA special bar code character that provides the scanner with start and stop reading instructions as well as a scanning direction indicator; the start character is usually at the right hand end and the stop character at the right of a horizontally oriented symbol.

Step LadderA code pattern in such orientation that the axis of the symbol from start to stop is perpendicular to the horizon so that the bars represented look like a step ladder.

SubstrateThe surface on which a bar code symbol is printed.

SymbolA combination of bar code characters, including start/stop characters quite zones, data characters, and check characters required by a typical symbology, which form a complete scannable entry.

SymbologyBar Code “Languages”. i.e.: Universal Product Code, Code 128, Interleaved 2 or 5.

Symbol LengthThe difference between the outside edges of the quiet zones.

METTLER TOLEDO Hi-SpeedProduct Application Check List (PACL)

Date: Project: Appl.ID: Customer: Rev. A

Submitter: Distributor:

Application: Industry: End User:

Application Description (More notes see page 3 of 3): No. of Pieces:

OBJECT (Measurements below in inches):Type: Max. No. of Barcodes for Each Object:

Reading Sides:Top Left RightFront Back Bottom

Box Minimum (in): Width Height LengthBox Maximum (in): Width Height Length Reading Station Maximum Length (in): Conveyor Height:

Reading Station Maximum Length (in): Conveyor Height:

READING STATION CLEARANCE (In Inches)Top Left RightFront Back Bottom

NOTE: DOF (Depth of Field) & RF (Reading Field) figure out how big the area is where bar codes have to be read!!!

DO NOT fill out DOF and RF field in DV9K application!

Fill one section for each side: Side DOF (in):Reading Field RF (in): Orientation:

ENVIRONMENTAmbient Temp. (ºF): Minimum Maximum

Celsius to Fahrenheit conversion rule --> °C = 5 * ( °F-32 ) / 9

Lighting directly over reading zone? Data TX to Host?

Any limitation to Transmission Point?

Special Software Required? No Yes (If Yes, specify below)

Preferred Product:

Operating Mode:

No. of Different Barcodes:

CODE #1Symbology:

No of Characters: Minimum Maximum

Narrow Bar (X) (mils):

Minimum Height (mm):

Maximum Length (Without Quiet Zone) (mm):

Are Code Samples Available?: Yes No

OTHER DESCRIPTION SECTIONS AVAILABLE ON NEXT PAGE

CONVEYORMaximum Speed Measured By: fpm Inch/s

Maximum Speed:

Conveyor Type:

Are the Parcels Justified? No Yes (If Yes, specify below)

Width (in):

Minimum Gap Between Boxes (in):

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Code Length

Bar Height

X-Dim (Narrow Bar or Narrow Space whichever is smallest)

TRANSPORTATION PLANE AND DIRECTION

Top - Front - Back - Bottom

Left - Right

RF

RF

DOF

DOF

Step Ladder

Picket Fence

Application DESCRIPTION and EVALUATION Form: Bar Code Description Addendum

METTLER TOLEDO Hi-SpeedApplication DESCRIPTION and EVALUATION Form: Bar Reading Side Addendum

TRANSPORTATION PLANE AND DIRECTION

Top - Front - Back - Bottom

Left - Right

RF

RF

DOF

DOF

Step Ladder

Picket Fence

NOTE: DOF (Depth of Field) & RF (Reading Field) figure out how big the area is where bar codes have to be read!!!

DO NOT fill out DOF and RF field in DV9K application!








CODE #2Symbology:






CODE #3Symbology:






CODE #4Symbology:






CODE #5Symbology:






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Space for Notes or Drawings

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