ID Systems

Sock Packaging - Note the wood floors...

Early in my career I became in involved in material handling systems more often than any other kind of project. For one thing, they were generally pretty simple from a controls perspective, just turning conveyor motors on and off, moving diverters in response to photoeyes and that sort of thing. They also meshed well with the packaging industry (NAS was my biggest customer). Products had to be both fed into and out of the machinery, so material handling became a great complementary offering to my controls and panel-building operations in the ’90s.

After forming relationships with several conveyor vendors, I started getting request to track product for production data. Often it was as simple as recording box barcodes into PLC data registers for plant systems to upload later, but as I started doing bigger jobs various other methods of tracking products entered into the picture. RFID, Inductive ID, Vision systems and Datamatrix reading were often combined into the same system and brought all the way up into the company SAP systems with redundant servers and provisions for local archiving. In particular, a project I worked on with several other companies for the VA automatically dispensing, packaging and even mailing pharmaceuticals comes to mind as a system that used virtually every type of ID system I can think of.

As part of the Primer, I have a section on ID systems. As the book is still a work in progress, I would as usual appreciate any input you have on either content or wording for this section.

RFID Tag with antenna

“RFID or Radio Frequency Identification systems are used as a means of tagging and identifying parts as they move within an area. Battery powered or passive RF tags are attached to objects such as pallets or containers. These tags contain serial number or itemized information concerning the object they are attached to for tracking purposes. Strategically located antennas or readers are located along the path of movement and can read or write information to and from the tags as they pass.
Most RFID tags contain at least two parts. One is an integrated circuit for storing and processing information, modulating and demodulating a radio-frequency (RF) signal, and other specialized functions. The second is an antenna for receiving and transmitting the signal.

There are generally two types of RFID tags: active RFID tags, which contain a battery and thus can transmit its signal autonomously, and passive RFID tags, which have no battery and require an external source to initiate signal transmission. RFID Systems usually operate either in the HF (High Frequency) or UHF (Ultra High Frequency) range of the radio spectrum.

Inductive ID systems serve a similar function to RFID systems but use a coil of wire similar to a proximity switch. The reader will excite an oscillator circuit in the tag which will transmit a serial code. Inductive ID systems can be lower cost and less susceptible to radio interference, but typically handle less information.

Bar code readers and tags are used to track parts also. The reader contains an LED or laser light source which reflects off of a tag with light and dark marks usually arranged in lines of varying thickness. These are then decoded into alphanumeric information. To cover a larger read area, the transmitted light will sometimes “raster” or move up and down.

There are several codes used for the bar code tags. The reader must be set up to read the proper code.”

As I pasted this section into the blog, I already see some things I want to change. Further explanation of the different formats of barcode (Code 39, Interleaved 4 of 5, etc.) could be useful, perhaps even as an appendix. Also the title of the section is currently “RFID, Inductive ID and Barcodes” under the sensors section and most people are going to be more familiar with barcoding, so maybe changing the order of the subjects might be good. Adding a paragraph on 2D or Datamatrix barcodes would also be good.

I have put out some feelers on getting help with formatting the book and have received lots of responses. I already have someone putting together the book proposal and someone else working on upgrading this website, but I am still not sure how I am going to approach the editing part. I like the idea of working closely with someone to make all of the information more readable and interesting, but face to face time whether in person or virtually will be an important part of the process. Since I have been out of town for several weeks I have kind of put things on hold, but I will be seriously looking for help probably by the beginning of September. Ideally it would be from someone who has some interest in the subject matter as well as being a good writer.

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