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Re: RFID Tracking [Re: Geoff Hannis] #74563 17/09/19 4:34 AM
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Roger Offline
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Originally Posted by Geoff Hannis

Another question!

If we consider a "typical" RFID system as deployed in a hospital ... how often does the system "ping" (interrogate) the tags? And is this setting adjustable (within limits) by you, the user (or manager)?
#Roger: 5 sec via TCP/IP; 1 sec via IR.

Are all passive tags automatically "pinged" in sequence, and can individual tags be "pinged" if you're interested in the whereabouts of a certain item (tag) or group of items (tags). I'm hoping that, in general, the answer to such questions is:- "Yes"!
#Roger: Only active tags are automatically pinged by the system.

Meanwhile, I'm assuming that active tags can "work the other way" - that is, reporting their position occasionally without prompting by a reader (interrogator). Presumably, each active tag can have its "reporting interval" individually set. smile

#Roger: Yes.

Last edited by Roger; 17/09/19 4:36 AM.

Make the impossible POSSIBLE. I know we all can and it is the wisdom to distinguish one from the other.

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Re: RFID Tracking [Re: Roger] #74564 17/09/19 2:16 PM
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Thanks for those responses, Roger. smile

As a general comment (and following on from my own "ad-hoc" research), it seems that - despite various assurances to the contrary by "RFID enthusiasts" (and/or sales people) - successful implementation of a hospital-wide RFID system is probably not a simple exercise.

There seems to be a fair number of pitfalls just waiting to snare the unwary, and a well-designed initial installation would need to allow (and budget) for various add-ons and fine-tuning events as time goes on.

Re: RFID Tracking [Re: Roger] #74565 17/09/19 2:40 PM
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Geoff Hannis Offline
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Originally Posted by Roger

Only active tags are automatically pinged by the system.


I can't agree with that, Roger (but maybe I was causing confusion by using the words "automatically pinged").

Surely passive tags do have to be interrogated by a reader in order to give up (return) their information. Passive tags are often embedded in "stores" items, such as linen in the laundry, and trays (etc.) in CSSD. But they only respond when asked ("pinged").

Meanwhile, active tags fall broadly into two types:- transponders and beacons.

For active transponder tags, as with passive tags, the reader will send a signal first, and if it's within range the active tag will reply with the information it holds. Transponder tags conserve battery life when the tag is out of range of the reader. In other words, like passive tags they (also) only respond when asked ("pinged").

With active beacon tags, the tag does not wait for the reader’s signal, but instead broadcasts its information every few seconds or so. Obviously beacon tags are useful when tracking portable equipment (especially when on the move). A compromise needs to be made to balance range (can be hundreds of metres) with battery life, but they carry on responding even when not explicitly asked (or "pinged"). The only question then remains whether or not any reader is within range to pick up the signal.

But how does a tag know of any type know where it is (in order to report its location)? There must be some sort of "triangulation" (similar to radio direction finding) going on. In other words, the tag does not know ... its the readers (acting collectively when in range) that "work out" a tag's location and log it in a database. smile

Re: RFID Tracking [Re: Roger] #74566 17/09/19 3:32 PM
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My own interest is what happens once the readers have reported back and updated the Tag ID (TID) record (date, time, location) in the RFID system database (each TID is a unique number, of course).

As mentioned earlier, if we wish to interface the RFID log with our favourite equipment database (CMMS) - so that equipment (tag) locations may be referenced against a Facility Map, or whatever - some form of intermediary step is required.

It would also be nice to be able to "ping" a certain item (or certain items) of equipment to ascertain its (their) current location directly from the CMMS.

Such interactions could be relatively straight forward if you have full information about the data structures at either end (either direction) of such data transactions. Otherwise, even if you are the developer of the CMMS (and are therefore able to insert "hooks" into your system), the structures used by the many and various RFID systems now available could only be guessed at. And even then, would the RFID system allow you to tap into it and extract data?

That's where the "middleware" comes in; and I haven't yet been able to conjure up a universal answer to that one. In fact I'm guessing that - almost by definition - bespoke code would probably need to be written for each scenario. smile

Re: RFID Tracking [Re: Geoff Hannis] #74571 18/09/19 11:00 AM
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Roger Offline
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Originally Posted by Geoff Hannis

Originally Posted by Roger

Only active tags are automatically pinged by the system.


I can't agree with that, Roger (but maybe I was causing confusion by using the words "automatically pinged").

Surely passive tags do have to be interrogated by a reader in order to give up (return) their information. Passive tags are often embedded in "stores" items, such as linen in the laundry, and trays (etc.) in CSSD. But they only respond when asked ("pinged").


You say it, as with passive tag, it does not "automatically pinged". They need to be energised by a reader.

Cheers!


Make the impossible POSSIBLE. I know we all can and it is the wisdom to distinguish one from the other.

My blog: http://biomedicalengineeringconsultancy.blogspot.sg/

Re: RFID Tracking [Re: Roger] #74572 18/09/19 12:45 PM
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There is a lot of clever stuff in RFID ... but I reckon that the way RFID readers work with passive tags is the "cleverest" bit of all - backscatter!

Originally Posted by RFID Insider

As the name implies, passive tags wait for a signal from an RFID reader. The reader sends energy to an antenna which converts that energy into an RF wave that is sent into the read zone. If a passive RFID tag is within the read zone, its internal antenna draws in energy from the RF wave. The energy moves from the tag’s antenna to power the chip which generates a signal back to the RF system. This is called backscatter. The backscatter, or change in the electromagnetic or RF wave, is detected by the reader (via the antenna), which interprets the information.

Passive RFID tags have no internal power source, and a standard passive RFID tag consists only of a chip and internal antenna; this basic structure is commonly referred to as an RFID inlay. Countless other types of passive RFID tags exist on the market, but all tags generally fall into two categories - inlays or hard tags. Hard RFID tags are durable and made of plastic, metal, ceramic and even rubber. They come in all shapes and sizes and are typically designed for a unique function, material, or application.

Certain industries, like healthcare, track the number of cycles that instruments undergo in punishing autoclaves. Specific passive RFID tags are designed to withstand extreme temperatures and accommodate for those types of applications.


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