Cognex Mobile Barcode Scanner SDK

What is Telepen?

A Telepen barcode symbology utilizes a continuous set of bars and spaces designed to encode all 128 ASCII characters. This covers standard printable characters such as punctuation marks and numbers. It also includes capital and lower-case letters as well as the complete set of non-printable control characters such as horizontal tab, carriage-return, linefeed, and so on.

Telepen can also represent numeric data in a double-density format by reinterpreting an ASCII character into a pair of numeric characters. Although there is nothing in the barcode to specifically distinguish between the ASCII or numeric modes. This means the interpretation of the data as ASCII or numeric is determined by the configuration of the Telepen reader.

These variable-length Telepen barcodes are one-dimensional and do not use shift characters for code switching. Telepen was developed in 1972 by SB Electronic Systems Ltd. in the United Kingdom. Telepen was made to be a competitor for Code 128 and Code 93 symbologies.

This symbology only uses two different widths of bars and spaces, but it was designed to be extremely reliable, even when printing a Telepen symbology using a printer not intended for barcode printing. Other names for Telepen include Telepen Numeric, Telepen Full ASCII, and SB Electronic Systems Barcode.




Decoding Telepen

Using a Telepen barcode scanner or a Telepen barcode generator is easy but understanding how this symbology works takes a little more effort. Unlike most linear barcodes, Telepen operates on a stream of bits. This means Telepen does not define independent encodings for each individual character.

Telepen can represent any bit stream containing an even number of 0 bits and applies to ASCII bytes with even parity. This enables Telepen to encode bytes in a little-endian bit order. Each string of bits is divided into 1 bits and blocks using the format of 01(*)0. Blocks must begin and end with 0 bits while using any number of 1 bits in between.

This Telepen barcode font format is then encoded as follows:

  • 1 is encoded as a narrow bar-narrow space
  • 00 is encoded as a wide bar-narrow space
  • 010 is encoded as a wide bar-wide space
  • The leading 01 and trailing 10 are both encoded as narrow bar-wide space, with additional 1 bits coded in between


Wide spaces are three times the width of narrow spaces. Thus, every bit occupies two narrow elements of space.

Telepen barcodes start with ASCII _. For example, the code 0x5F makes the bit stream 11111010. As a result, it is encoded as five narrow bar or narrow space pairs, followed by a wide bar or a wide space.

Telepen barcodes end with ASCII z. For example, the code of 0xFA makes the bit stream 01011111. This is encoded as a wide bar, or a wide space followed by five narrow bar or narrow space pairs. At the end of the Telepen barcode, there are repeated narrow elements concluding with a pair of wide elements.

However, the beginning always features a wide bar first. This means if the code is scanned in reverse, the wide space will be recognized first. On top of per-character parity bits, a Telepen barcode includes an overall modulo-127 checksum.


Who Uses Telepen Symbology?

Primary users of Telepen include universities and libraries in the UK and other countries. The automotive industry, Ministry of Defence, and many other organizations or businesses use Telepen barcodes as well.

How Do We Help Developers Using Telepen Symbology?

If you need to create or decode Telepen barcodes, or even just use Telepen encoding/decoding in your next app, the easiest way is by using a reliable Telepen scanner. The Cognex Mobile Barcode Scanner SDK supports Telepen detection, enabling developers to gather relevant workflow and application data regarding Telepen symbology.

Generating or scanning Telepen symbologies accurately is important for both developers and businesses alike. Decoding Telepen barcodes with precision is equally important, which is why you need the right Telepen reader to get your app ready for launch sooner.

You can download the SDK for free by registering on the Cognex Mobile Barcode Developer Network. In addition, the Barcode Scanner SDK supports a broad range of symbologies to meet your growing development needs.

Get the Telepen decoder SDK you can trust as a developer. Check out our convenient mobile barcode scanner and SDK to start saving time so you can get back to developing your next big app idea.

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