Serial Cables - Serial Data Communication

Serial Connectivity (customerservice@L-com.com)

As technology has advanced and we've needed to pass more and more data more and more quickly between devices, serial communication has become more important. Serial communication transmits data in a precise series so that minimum skewing or modulation occurs. While it isn't as fast as parallel communication in short distances, it is superior, especially in long distances and when speed isn't exactly an issue, to older standards.

In order to make sure that all manufacturers that used serial communication could connect together, the EIA/TIA created the RS-232 standard. This way, serial keyboards, joysticks, scanners, and other equipment could be connected to terminals like computers. That same standard is followed today, but affects mainly the devices being connected, not the connection itself. Two devices with RS-232 compliant ports should be able to connect with any serial cables.

The most common connector type on a serial cable is the DB-9 connector. This D-Subminiature style connector has 9 pins in a "D" shaped footprint. L-com carries a wide variety of these types of cables, including economy D-Sub cables, deluxe, and premium (double shielded) style. These are all molded and factory terminated and tested.

DVI Video Standard

Digital Video Interface (DVI) - What is it?

(customerservice@L-com.com)

DVI is one of the video standards for the emerging field of digital video. As you get newer televisions, HDTV boxes, video cards for PCs, and other video equipment, you may see this type of connector more and more.

The connector is shaped vaguely like a D-Sub connector, with screws on either side to hold it mounted. It has up to 24 pins in the middle, plus four pins possibly around a bar to one side. I say "up to 24 pins" and "possibly around a bar" because there are actually several types of DVI connectors possible.

Three DVI signal types

In instruction booklets that reference the DVI cables you need, you may see a letter after DVI, like this: "DVI-D". There are actually three different types of DVI: DVI-A, DVI-I, and DVI-D. The -A is for analog only, the -D is for digital only, and the -I has both analog and digital pins. How can you tell the difference? The easiest way is to look at the bar at one side of the connector. The four pins around it are for analog signals, so if you do not have those pins, the connector is a DVI-D: it only includes digital lines. If you do have pins around the bar, and most of the pins in the center (there may be a strip of pins missing in the middle. More on this in a second), you probably have a DVI-I connector. If you only have 12 of the middle pins, you probably have a DVI-A connector.

On a male connector, usually on a DVI cable, it is important to know which type it is because if you try to plug a connector into a female port that doesn't have enough holes for the pins, then some of the pins may bend, destroying the cable. On the other hand, female DVI-I connectors can accommodate both DVI-D and DVI-A connectors because they have holes for all of the pins. Most newer DVI equipment is coming with DVI-I connectors standard for that reason.

Single Link and Dual Link DVI

Single Link and Dual Link has to do with how many channels of transmission are available in a cable assembly. You can visually tell a single link male connector from a dual link by the centermost vertical strip of pins. If they are missing, then the cable is single link only. If they are there (meaning all 24 pins are present), then the cable is dual link.

Contrary to many beliefs, dual link isn't really "better", in that the picture quality is the same. Dual link is primarily for getting up to very high resolutions, usually too high for most TVs to get to. Dual link DVI can reach a resolution of 2048 x 1536 at 60 Hz Refresh Rate, sometimes called QXGA or Quad Extended Graphics Array. In most commercial cases, this isn't necessary.

Coaxial cable

What is Coaxial Cable? (customerservice@L-com.com)

Coaxial or Coax cable is so named because the signal inside the cable runs on two (co-) axies: the center conductor and the shield. This is a relatively old cabling technology that was originally developed for military use. Coax cables were found to be so durable and efficient at carrying all sorts of signal types from data, video, audio, and more, that the standard soon became commercialized. Today, coax remains a very popular cable assembly type for cable TV, antennas, high-end audio/video equipment, and security equipment.

Though there are a few standards of coax cable available on the market, L-com only really carries the "RG" styles. RG stands for radio guide, and each cable type is generally called by RG followed by a number indicating the standard number of the cable. That is sometimes followed by a letter to indicate a sub-standard, and then the letter "U" to indicate that the standard is universal. But all this doesn't help you figure out what kind of cable you need!

With coax, the application generally dictates the kind of cable. Video cables nearly always use 75 Ohm styles of cable. Data and antennas usually use 50 Ohm styles. The different styles may have different flexibilities, diameters, attenuation, jacket types, and other factors that make one cable the ideal fit.

If you have an application but don't know what cable you need, try giving us a call or emailing directly to our tech support group at support@L-com.com. You may also find our Coaxial Cabling Tutorial helpful, available free on our web site.

The holidays are drawing to a close, but L-com sales are still on!

Plenum Patch Cables (Fiber Optic and Ethernet UTP) Sell-Off (customerservice@L-com.com)

As the year ends, we took a look around our massive warehouse and noticed many boxes of custom Plenum rated cable products built for one of our customers who didn't end up needing them. Well, we don't need them either, so we've decided to sell them at incredible prices just to give us more space!

The link to the items on sale is here:

http://www.L-com.com/PlenCloseout

Among the items are a variety of multimode and singlemode fiber optic patch cables, OFNP or Plenum rated, and various colors and lengths of Cat 5e and Cat 6 rated Plenum Ethernet cables. And the prices are so low, some of them are even cheaper than our PVC cables!

Along with that, the Overstock Sale that we started a couple of weeks ago is still going on, so check that out as well.

Hope your New Years is a happy and prosperous one!

L-com's End of Year 2006 Sale!

HAPPY HOLIDAYS (customerservice@L-com.com)

Happy holidays to our blog readers and L-com customers! As a token of appreciation, our sales reps sent out the below email on Wednesday:

Hi,

Happy Holidays and thank you for being an L-com customer! 2006 was a very successful year for me here at L-com, and I’m hoping it was a good year for you too.

Because I appreciate your business, I want to make sure you know about a special End Of Year Sale going on here. I picked a couple of items I thought might interest you, but if you want to see a complete list of many more items click here.

You can’t access this special sale list from our home page, so I’m sending you the link specifically by email. Copy and paste it into your browser:

http://www.L-com.com/2006EOYsale

If you want to discuss your projects or connectivity needs, please give me a call or send me an email! I look forward to working with you in the year to come. Have a happy and prosperous New Year!

Thanks,

L-com Sales Department

TRD855BL-7 $0.99 69% Off Regular Price!

DGBH15F $3.25 60% Off Regular Price!

CC58C-5 $4.00 53% Off Regular Price!

I want to extend the same invitation to our blog readers! If there is anything we can do for you, let us know!