TIA, EIA, DTE, DCE, FYI, TMI…? What’s it all mean???
If you’ve been shopping for D-Sub products lately, you may have run into some battles with terminology. Your product manual may require a TIA/EIA link while your computer has an RS-232 D-sub port. You may have a DE9 M/F cable but you are told you need a DB9 M/F cable…your kid may be texting you LMAO and you may be thinking, possible typo aside, "did my son just call me a lamo?"
We’d like to help you sort it all out.
What’s in a name…
TIA/EIA labeling refers to the RS-232 standard. In an effort to reclaim the product that the telecommunications and electronics industries jointly created fifty years ago, they have rebranded the standard more than once to reflect their influence . TIA stands for Telecommunications Industry Association. EIA stands for the Electronics Industry Association. You can rest easy knowing that they all refer to basically the same thing, and that just about any d-sub cable or product sold today will meet this standard.
And what is that thing?
RS-232, or alternatively, TIA-232/EIA 232, has managed to thrive in the industry for 50 years because even today it still does fills its own shoes, and it still remains competitive with the newer, flashier protocols for the following reasons:
Reliability: Data transfers can be counted on with minimal risk to lost data bits
Ease of use: very little demand on CPU, very little user hassle: networks can be established with a single cable
Cost effectiveness: older systems set-up to talk via RS-232 can simply be maintained-cables and accessories abound
And what is DTE and DCE?
DTE, or Data Terminal Equipment is what converts data from user form, as well as to user form, and thus, usually refers to a computer. DCE, or Data-Circuit Terminating Equipment , usually refers to devices such as modems. What you need to know about these devices in regards to their use of the RS-232 protocol is that computers and modems use opposite channels to send and receive data. A computer sends data on pin 2, and a modem receives data on pin 2, making the devices complimentary. Naturally, the former receives on 3 and the latter sends on 3. A standard d-sub cable will make communication between the two devices possible.
On the other hand, in order for two computers or two modems to network, a cable known as a null modem is required. This cable essentially flips the wiring so that pin 2 sends data to pin 3 and vice-versa. Hand-shaking lines are crossed as well.
Also tricky…
DE9 is the proper name for a 9 pin D-sub connector, but due to a misunderstanding of the designation of the second letter, E (denoting shell size), people began calling it DB9 after DB25 connectors. Again, the two terms are interchangeable for sales purposes.
Copy right material M2Cables, Inc. No reproduction without author permission.
REFERENCE J. Axelson, Serial Port Complete: Programming and Circuits for RS-232 and RS-485 Links and Networks, Lakeview Research, Madison, WI, 1998
Tags: TIA, EIA, 9 pin connector, data transfer, RS-232, D-Sub, serial communication
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