23 April 2013
We are pleased to present the following technology guides.
This type of barcode scanner is held in the hand and pointed at the barcode. Depending on the technology used the scanner may need to be held close to the barcode, a short distance away or at distances of up to several metres.
All general purpose hand-held barcode scanners can read the EAN13 retail barcode and other barcodes such as medium size Code39. More advanced hand-held barcode scanners can read barcodes with very narrow bars, barcodes where the symbol is very wide, various types of 2d codes, and codes which are Direct Part Marked.
Most hand-held barcode readers are connected by means of a cable. Others use short range wireless links.
Finally it is important to ensure that the ruggedness of a hand-held barcode scanner matches the environment in which it will be used.
The lower cost hand-held barcode scanners use CCD technology and work well with commonly encountered barcodes such as EAN13.
What using this technology means in terms of operation is that the reading window of the scanner has to held in close proximity to the barcode and the width of barcode symbol should not exceed the width of the reading window.
CCD technology readers are available in several sizes. Typically the reading window width is 65 or 90mm.
When using CCD technology scanners you should ensure that the quality of the barcode is reasonably good.
Linear imagers were developed from CCD technology and are sometimes called Long Range CCD Scanners. They should not be confused with long range scanners which can work over several metres.
These scanners are usually a little more expensive than CCD scanners but offer significant advantages.
What this technology provides to the operator is the fast, comfortable reading of most types of linear barcode.
The barcode scanner can typically work at distances of 200mm to 400mm from the barcode and the maximum width of the barcode can be quite large.
Linear imagers repeatedly scan the barcodes many times each second and can handle damaged or poor quality barcodes.
This type of scanner has no moving parts and is very reliable.
A further plus point is that this type of barcode scanner offers no hazard to human eyesight.
As a general rule you can rely on this type of barcode scanner to meet the requirements of most 'normal' linear barcode applications.
Hand-held laser barcode scanners have evolved from one of the earliest barcode reading technologies.
At the lower end, price and performance overlap with that provided by linear imagers.
If you need greater working range, or a bit more barcode symbol width, then laser scanners may be appropriate.
As a cautionary note it should be pointed out that laser barcode readers need to be treated with respect. The risk to human eyesight, no matter how slight, should always be considered.
Hand-held area imager barcode scanners are similar to digital cameras. An image of the entire barcode symbol is captured and decoded into data.
This technology lends itself to reading 2d codes and linear barcodes in any orientation.
This area is expected to show the biggest advances. Hand-held area imager barcode scanner products have already been released which can read several barcodes at once, read at a large distance or read exceptionally difficult Direct Part Marked codes.
Most hand-held barcode scanners are connected by cable to other equipment.
The connectors and the method needs to be matched at both ends.
Some hand-held barcode readers allow you to change the connector cables to suit your preferred method. For others the cable and therefore the method is fixed.
The Keyboard Wedge is a simple general purpose connection method which can be used with PCs with PS2 keyboards and Computer Screens with attached keyboards.
In this method the barcode scanner is fitted with a Y shaped cable with DIN or mini-DIN connectors PC keyboard connectors. Each arm is inserted into the connection between the PC and the keyboard. Similarly the method can be used with Computer Screens with the aid of appropriate cables.
In this mode data decoded from a barcode appears on the PC or Screen as if typed in through the keyboard. The usual function of the keyboard remains unchanged.
This method has the advantage that it requires no set up and no changes to the application software.
Computer Screens may require an external power supply but generally there is sufficient power in PC keyboard circuits to drive barcode readers.
This is now the most common method of connecting hand-held barcode readers to modern PC equipment.
The barcode scanner is fitted with a USB cable which is plugged into a USB port.
No set up is required and the barcode data can be used with any program that accepts keyboard input.
In some cases an external supply may be required to power the barcode reader.
This method allows connection to any RS232 compatible equipment. The barcode scanner and the other equipment have to be setup to ensure that the line speed, parity, word length and stop bits match.
The barcode reader is fitted with a cable which is terminated with a DB9 or DB25 connector which is plugged into a COM port on the other equipment.
RS232 connection will only work with application software specifically designed to accept input through COM ports
RS232 connections nearly always require an external power supply.
This is the USB equivalent to RS232 and works with modern PC equipment.
The barcode reader is fitted with a USB cable which is plugged into a USB port.
USB Serial connection will only work with software drivers and application software specifically designed to accept working through Virtual COM ports
In some cases an external supply may be required to power the barcode reader.
Wireless connections give a cordless working range of 10 to 100M depending on local conditions and is useful where cable connections hamper the operation or greater mobility is required.
Wireless hand-held barcode scanners communicate with a base station which is connected to other equipment via one of the cabling methods described above.
Sometimes the base station is combined with a charger dock. Where round the clock working is required barcode scanners with exchangeable rechargable batteries may be used in conjunction with dedicated chargers.
If the barcode scanner is out of range of the base station the scanner will usually warn the operator and if appropriate the scanner may store any transactions until normal service is resumed.
Today barcode readers designed for the office are remarkably sturdy and if used appropriately will give long working life.
However, if heavy handling, dust, water spray, temperature extremes or vibration are problems it is preferable to use equipment with an industrial specification.
Industrial equipment normally comes with longer warranty and is generally cheaper than having to make multiple replacements of office grade equipment.
Presentation scanners are devices which normally sit on the sales counter or work bench. The operator picks up the barcoded object and shows it to the barcode scanner.
Where the object is too large or too heavy to be handled easily some smaller presentation scanners can be picked up and used like a hand-held scanner.
Most presentation scanners are geared to working with EAN13 retail barcodes. Some can handle a wide range of linear barcodes and some can handle a limited range of 2d codes.
In general to achieve fast performance the quality of the barcodes should be good.
The simplest form of presentation scanner consists of a hand scanner which is supported by a stand. The barcode has to be placed accurately in the field of view or presented to the reader with some care.
Purpose designed presentation readers generally offer a wide field of view and a large depth of field which makes the barcode reading process easy and quick.
The presentation scanner is connected by cable to tills or other equipment and the connection method used is normally USB, RS232 or Wedge but may in some instances be proprietary.
Presentation scanners require power and this is usually provided by a dedicated supply or taken from the other equipment over the connection cable.
The type of cable required to connect to the other equipment will depend on the connection method, power issues and in some cases the manufacturer of the other equipment.
Unattended barcode scanners are sometimes called fixed position barcode scanners.
They are typically embedded in equipment or mounted alongside conveyors and work without operator intervention.
The choice of unattended scanner will depend on factors such as the type of barcode, the orientation of the barcode, the distance from the scanner to the barcode, the required speed of reading, the method of triggering and the connection method.
Linear barcodes can be read using unattended scanners which use CCD, laser and area imaging technology.
Unattended CCD scanners offer an inexpensive means of reading linear barcodes on stationary or slow moving objects which are close to the scanner reading window and where the orientation of barcode is well controlled. This type of scanner is typically embedded in instruments.
Laser based unattended scanners are typically used to read linear barcodes on objects which are travelling on conveyors. The scanner usually produces a single scan line and the best arrangement is where the entire height of the bars passes through the scan line.
The laser scanners can be placed at some distance from the barcode and the read rate can be very fast.
Some laser scanners offer raster scanning and are able to read several barcodes on a single pallet label.
Most area imager unattended scanners can read linear barcodes in any orientation. The maximum read rates for linear barcodes are much lower than that possible with fast laser scanners.
2d barcodes can be be read by area imagers and some scanners have the ability to read Direct Part Marked codes. Most area unattended scanners come with built-in illumination which can be switched off and replaced with external lighting which can be positioned to reduce specular reflection.
To a large extent triggering and the connection method are interlinked.
Triggering may be by one or more of the following methods, the scanner may continuously trigger itself without external intervention, the scanner may trigger itself when it detects the presence of an object in its field of view, the scanner may be triggered by software command or the scanner may be triggered by an external electrical signal.
The available connection methods can be one or more of the following, Keyboard Wedge, USB Keyboard, USB Serial, RS232 and RS485.
Keyboard Wedge connections may be used with PC equipment and computer screens. Since this method does not permit communication to the scanner this type of connection is typically used with low cost unattended scanners running continuously or triggered by the presence of an object.
USB Keyboard connections are used in a similar way to the Keyboard Wedge.
RS232 connections permit two way communication and allow software trigger codes to be sent by an application running on equipment connected to the scanner.
USB Serial connections are used in a similar way to RS232.
Some of the fast unattended laser scanners can only use RS232 or RS485. Both of these allow connections over extended distances. RS485 is effectively a multi scanner connection version of RS232.
Finally some scanners can be triggered by an electrical signal from a device such as a photocell.