USB to Serial Adapters and Kit Suggestions

Way back in 2008 or so I got a couple of serial adapters for my laptop so I could set up various network devices. Most business class devices, even in the 21st century still use the serial port approach to first set up. Something about security or making things harder for technicians to do their job.

Since laptops don’t often come with serial ports anymore this makes things difficult to set up.

Recently I misplaced the best serial adapter I have ever worked with. The IOGEAR USB 2.0 to Serial Adapter I purchased at Best Buy in probably 2008 or sometime around then. I’ve had other adapters, but this one has worked with every operating system from Windows XP to Windows 10. I think I’ve even plugged it into a few Linux boxes and not had to do anything weird to get it to work.  Something  I can’t say with others.

The only real drawback is it has a short cable. I’m always a little jealous of the ones the phone guys carry with the 9 foot cables, but they always break on them. This one went through daily heavy use for several years, and wherever it is I’m sure still works after nearly decade. I replaced it recently with another one exactly like it.

Anyway, I highly recommend IOGEAR stuff, I’ve got an old KVM switch and some other stuff they’ve made and it’s all managed to outlast a lot of the more expensive stuff I’ve bought over the years.

Kit Suggestions

I’ve founds a few cables need to go with this particular adapter over the years. This is a ‘least number of cables you need kit’.

  1. Female to Female Serial Cable – This is what most devices need. Most network appliances are just computers with a regular serial port sticking out of them. Get a really long one of these. The Amazon link is for a ten foot cable. But you can select a three-foot, six-foot, or up to a hundred foot cable. I’ve never needed more than a ten foot cable.
  2. Female to Male Serial Cable – Some appliances have a backwards serial connection like this. I think they expect you’ll have a serial adapter with a long cable. Weirdly they’ll usually come with a cable like this. ShoreTel devices are one big example of this kind of device. I’ve never needed a super long one of these, but it also will double as an extension. I always just carried a six-foot one and kept it coiled up.
  3. Roll Over Cable With Null Modem – Essentially a “Cisco Cable”. You can get one out of the box a switch came in. The Amazon link there has a generic one for $4 but, honestly if you are buddies with some of your local IT guys you can usually get a hand full of these for free. Every time you buy a Cisco equipment or most other equipment that uses these, it usually comes with one. If you have ninety switches, you inevitably have ninety of these lying around.
  4. Regular RJ45 Null Modem – Some devices need weird pin outs and they usually use RJ-45 connections so having a regular old null modem is great and you can just make whatever cable you need. The link comes with two. Some networking equipment will come with these and a rollover cable that detaches so it’s worth watching out for that.

If you need a crossover cable, my suggestion would be to get a short male to female crossover cable, not a female to female one. I’ve never actually seen the need for one, but they sell them so I’m assuming there’s equipment out there that uses them.

DSL vs. Cable Internet, What’s the Difference?

This is something that I’ve been asked a lot recently. A lot of people don’t really understand what the differences between the two most common broadband internet types are. So as someone who has worked for not one, but two internet service providers I feel qualified to break it down for people.

If you’re looking for what you need to get connected at home, I’ve set up an Amazon store that has the products I recommend on it. Check it out and consider buying from there, the prices are almost always lower that what you’ll find at the retail stores.

What is DSL?

DSL is an acronym for Digital Subscriber Line. It’s basically a technology that sends data over a normal phone line (POTS line). Practically all DSL service in the US is actually “ADSL” which means Asynchronous Digital Subscriber Line. The only thing that means is that the download speed will be higher than the upload speed.

DSL is usually sold by one of two kinds of providers. The first type is the top-level phone company directly. By top-level I mean whoever actually owns the infrastructure that goes to your home. In the US this is usually a larger company like AT&T, or Verizon. There are also some smaller companies like Windstream that provide service directly to smaller towns.

The other DSL provider will be  a local, or semi-local re-seller  This is a smaller company that resells services for the top-level company. Basically they buy the loop (the physical wire or circuit that goes to your house or business) and sell it to you and then give voice and data over it themselves. Most of the time these smaller companies are a lot cheaper as they’re getting the loops from AT&T for a few dollars and then reselling to you for a profit. They’re also the most limited in what they can actually do. Typically their customer service is better to make up for speed deficiencies.

DSL, like all data connections, is limited by distance from the Central Office (DSLAM). You need to be within a mile (~2km) to get the best connection. After that first mile the guaranteed speeds will drop until you get about 19,000 feet (roughly 3.5 miles or ~5km) away. In my experience the smaller providers probably won’t offer you service at that distance.  This is where your re-seller companies fall short. Big companies like AT&T will put repeaters out so they can sell to more people at higher speeds. Smaller re-sellers typically can’t or more likely won’t do this so they are limited to a circle about three miles around the central office.

If you live in a small town you can safely assume the only central office is down town. Small cities will usually have multiple central offices so it might be difficult to find what kind of service might be available to you specifically. Unfortunately I don’t know of any tool available to the public to look this stuff up. Your internet service provider/phone company has access to these tools with the top-level company and they can tell you how far you are away.

Speeds vary from place to place. I’ve seen as high as 25Mbps download speed and as lows as .768Mbps download. For some reason download speeds with DSL are parcelled out in multiples of three until you hit the 20Mbps range, so you can expect to see 1.5 (half of 3), 3, 6, 12 and 15Mbps speeds advertised. Upload speeds are typically under a megabit as most home consumers don’t need upload speeds faster than that. If you do need faster upload speeds you can usually ask for them. Re-sellers are more likely to work out a deal with you than the bigger companies. Typically the lowest speed any company offers is 1.5Mbps download and .3Mbps upload (they’ll say 300Kbps to sound bigger). Of course the smaller the town the slower the speeds most of the time.

DSL service will require you to have a modem. Some companies will just give you a modem, most will just or rent you a modem at a discount with a contract. You can also provide your own and they’ll usually have a compatibility list on their website. Most Best Buy stores will carry modems compatible with your local service. I have an Amazon store with various equipment on it that is universally compatible. I HIGHLY recommend if you are considering AT&T that you get a modem from them as they will actually set it up for you. Be aware that if you provide your own modem, most DSL providers won’t give you any real technical support.

Note: I’ve seen some conflicting information about the distances I talk about above, some of it from sources on the internet, and from other people that have worked in the industry. I chose the numbers above because they were what I have been told most commonly over the phone, and what I had to tell customers when I worked at an ISP. Different technologies, geographical considerations, city size, line quality and other factors can drastically change what speeds you can get. The above distances are just a common rule of thumb, not an exact measurement for everywhere.


What is Cable Internet?

Cable internet service is a data connection that is provided through your cable service provider. The same coaxial line that your cable television comes in can be used to provide data (and voice services!) as well.

Most cable companies will provide some sort of internet service in addition to television. You’ll mostly hear cable internet referred to as “DOCSIS” (Data Over Cable Service Interface Specification). There are as of this writing three major versions of this. There’s DOCSIS 1, DOCSIS 2, and DOCSIS 3. There are a few minor versions but most home users don’t have to worry much about that.

This sort of internet service requires a few extra steps to set up but is usually more available to consumers. If you can get cable television, you can usually get cable internet. I am not sure what the limitations are as far as distance goes, but those limitations do exist. Some smaller towns may not have cable internet available even if the television service is. This is rare but I’ve seen it. Most people in those towns usually have satellite television/internet anyway because of how rural they are, at least in the United States.

It’s been my experience that cable providers can give you far higher speeds than DSL in the same area. The DOCSIS 3.1 standard should allow for 10Gbps download speeds. Even here in Amarillo, with a measly two hundred thousand population you can get 100Mbps download service to your house in many places if you are willing to pay for it. Smaller towns can still get 8-12Mbps service download speeds with cable if you are actually living inside the town.  Standard service seems to be in 20Mbps range for cities.

Like DSL, cable is delivered with asynchronous speeds. Your download speed will be higher than your upload speed. The trend is to give between 1 and 2 megabit upload speeds even if the download speed is far higher. Cable internet download speeds seem to be advertised in multiples of five for some reason. You’ll usually see 2.5, 5, 10, 20, 30 and 50Mbps speeds advertised.

A lot of cable companies will give you a modem if you ask. Usually they’ll rent them to you for $5 a month or so. If you are lucky they might just give it to you with a contract. As cable modems tend to burn out after two years or so, I recommend buying the modem yourself with home cable internet service. The biggest reason for home users is the leasing arrangement will cost you more over time, and you can usually get a compatible modem cheaper from Amazon or Best Buy than your cable company. If you have a business, lease the modem. Because they tend to burn out, the cable company will replace worn out leased modems and you get priority service (Sometimes you can just take the bad modem to the local office yourself and they’ll swap it out for you right there). If you as a business owner don’t want to lease the modem, buy two identical modems and keep one unopened as a spare.

Unlike DSL providers, it has been my experience that the cable companies will give you a bit more technical support if you provide your own modem. This is primarily because of how cable internet service works, you have to call them to activate the modem. If the modem is compatible with their service, they set it up for you. I’ve got an Amazon store set up that has modems compatible with most of the US cable providers.

So What’s the Real Difference?

The difference boils down to speed, who provides the service, and how big your city is.

Cable tends to be faster, cheaper and more available than DSL in many places. At least in my experience it tends to be a bit less reliable. You’ll have a few more outages per year than DSL. Usually cable companies tend to just say you can’t get service in an area and not telling you that your speeds will be lower if there’s a distance issue. One big disadvantage to cable is that there is usually one single provider that has a monopoly on the area so you can’t call somewhere else for a better quote.  Cable internet comes through your cable television provider.

DSL tends to be a bit more reliable, but it usually slower and a little more expensive in some areas (not always, sometimes it’s far cheaper than equal cable, but the top speeds aren’t as high). It also tends to be less available in smaller towns than cable. The other problem is that sometimes your next door neighbor can get a very fast speed, but you can’t.  One big advantage with DSL is that there are usually multiple competing companies in an area that can provide it. DSL comes through your telephone provider.

Either way you can get DSL without land line (POTS) phone service really cheap in most cities. If you get your DSL through a major company like AT&T there are some perks like free WiFi access at certain hotspots, which is awesome for people who travel a lot. If you get cable internet you usually get complimentary basic cable television with it, and you can usually also get your land line service as well for a discounted rate (I know people who have worked out their cable service in such a way that the internet is free and they pay a dollar for a land line).

There are advantages and disadvantages to both types and you should really call both kinds of providers and see what they have to offer before deciding. At the end of the day it really comes down to where you live and what you’re willing to pay.

I know I mentioned this at the beginning of the article and once in the middle, but I’m providing another link to the Home Internet Needs store on Amazon I set up so you don’t have to scroll looking for it.

Home Routers and Why You Need One

I like to think of modern home routers as your first line of defense against the bad things out there on the internet. They are super important, and everyone with internet access should have one. Most new routers have a lot of features that surpass “route traffic to the internet and back”. Your basic Linksys router will have the following features, and a lot more right out of the box.

  • Basic Routing – Get your traffic to the internet, and the internet’s traffic to the right computer. Some of them can even do internal routing.
  • Network Address Translation – Lets you have more than one computer share an internet connection without your ISP really knowing it.
  • Wireless Networking – Connect your laptops and other wireless devices to the home network.
  • Basic Firewall – Protect your stuff from basic attacks originating from the internet.
  • VPN Passthrough – Lets you connect to your work without any re-configuring your firewall.
  • Quality of Service, Port Forwarding, MAC address restrictions, Diagnostic Tools, Data Usage Tools, DNS, DHCP and tons more.

Your basic $50-$80 wireless router will have at least all these features, and probably a lot more. Most people just use them to put Wi-Fi in their house if their internet provider didn’t just ship them one.

One major reason to get a router is that it will actually save you money in the long run. It’s not terribly surprising if your cable modem or DSL modem goes out a year after you buy it, and you’ll have to get a new one. If you have a combination router/modem then it’s going to be a lot more expensive. A good router that wasn’t the low-end $20 one at Wal-Mart will typically last five years without much more maintenance than occasionally unplugging it and plugging it back in. So instead of having to buy that $200 router/modem combo just because the modem part when out, you can just go get a $30-$80 modem once every year or so and be fine.

The other reason is the firewall. Most routers have basic firewalls that just work, no configuring by you is needed. If you’re hooking your PC directly to the modem, you will be depending on Windows Firewall, or whatever Apple uses. This isn’t a good idea. Windows Firewall isn’t that great, and a lot of malware just flat turns it off. Router firewalls can be a lot tougher to get around.

What Routers Are Compatible With My ISP?

Unlike modems, there’s not a lot to router compatibility. If you go to your local Best Buy, you’ll see about two dozen models of wireless router. They’ll range from $30 to $250 and have all sorts of guarantees on the front about gaming and video streaming.

The reality is, most of those claims are utter bull. At very least they are misleading. They’ll compare their routers to a competitors low-end router, show how much better it is then make a bunch of claims about speeding up video streaming from the internet. The competitor’s router will have the same thing on their box. Some will even say “Compatible with Suddenlink!”. Yeah, they’re all compatible.

All routers work with TCP/IP and the only major differences are speed, chipset and features you probably don’t care about. Wireless network speed is the biggest thing to look for. You want to get a Wireless N router. It has a range of roughly a thousand feet as opposed to the 300 feet a G router provides, and you get get data speeds up to 300Mbps as opposed to 54Mbps (depending on the security you choose).  Even the speed is misleading because you’ll be lucky to get 64-75Mbps on your wireless if you secure it right. A lot of that depends on your network card and what your house is made of.

Now I know you probably just want me to suggest a model. I prefer Linksys E2500’s. They’re right at the $80 mark and have just about everything even an advanced user could want. Here’s a link if your ad-blocking software are hiding the ads: Cisco E2500 Router

If you are an Apple user, I suggest either the AirPort Extreme 5th Generation or the Base Station with the print server port on it. The only drawback to these for a PC network (other than price) is they don’t have as many wired ports. Otherwise there aren’t any real differences between the Apple product and the Cisco product except the base station has a print server and some iTunes features you can take advantage of on your Mac, iDevices, or PC.

How To Install a New Cable Modem

So your cable modem went out, you don’t want to take an hour off of work to have a technician come over. How can you replace it? Well you can’t just plug it in like you can with DSL and it work. Also most cable providers don’t have a good ‘set it up yourself’ method as many DSL companies do.

Step 1 – Go get a new cable modem. Most big box electronics places like Best Buy Sell them. Refer to the notes at the end of the post for what the two major ISPs now use before you go shopping.

Step 2 – Remove the old modem. Remember what cables went where.

Step 3 – Unplug the power from your router, or turn your computer off if connected directly.

Step 4 – Plug in the new modem starting with the coaxial cable (this is the big cable with the screw on end. Do not use tools to connect this as you can damage the connector on the modem. Tighten this with your fingers until it is “just tight”.

Step 5 – Plug the ethernet cable in next (the one that looks like a large phone cable). Do NOT plug the power in.

Step 6 – Call your Internet Service provider and get to the tech support option. I’ve included phone numbers below for Comcast and Suddenlink.

Step 7 – Tell the tech support person your account info so they can look you up then tell them that you want to “provision a new modem” and take the old modem off your account.

Step 8 – They will ask for the MAC address of the modem. This is usually labeled clearly on the bottom of the modem. Most manufacturers print this on the box as well. MAC Addresses look like this 00-00-00-00-00-00. They contain numbers and the letters A through F.

Step 9 – They may ask for the serial number too. Motorola serials are something like 24 digits long and has only numbers. Don’t’ confuse this with the Customer Serial which is shorter and has letters.

Step 10 – Follow the instructions the tech support agent gives you. You may need to reboot some stuff a few times.

Step Done – You should have internet!

Modems By Provider

I’d love to add more links here. If someone would send me information for their local cable internet providers. 

I highly recommend the Motorola SB6121 modem. Both Suddenlink and Comcast list it as compatible with their service. It’s easy to find at Best Buy or you can order one here: Motorola Surfboard Cable Modem SB6121

Comcast – Comcast has a modem compatibility tool here:

Suddenlink – You need at least a DOCSIS 3.0 modem to get the best service. The compatibility list here:

Tech Support Numbers

Comcast – 1-800-XFINITY – 1-800-934-6489 is the number in real person digits. This is their main 800 number listed on their website.

Suddenlink – 877-794-2724 is the tech support number listed on their website but may be regional to the southwest. There is also 1-888-822-5151 which might be all purpose.

If you hate working the menus here’s a link to Get Human’s instructions for getting a human:


I do not endorse the Get Human method, but some people might find it useful.

Motorola SB6121 Instructions

Here’s a link to Motorola’s quick start and user guide instructions for the cable modem I recommend. The quick start guide is included in your manual.

Quick Start Guide – This is quick guide to installation.
User Guide – This one has a little more details on how to set it up and what the lights mean.