poe injectors

[Number 42]

I'm in the planning stages right now for a new home. The wife wants cameras, probably 6-8 indoor and out. My thoughts are poe ip cameras from Foscam. I am thinking these would connect to a switch and on to a dedicated laptop and then to the NAS. If I opt for a non-poe switch, and use a poe injector such as http://foscam.us/active-poe-injector-98.html, will it only power the one camera or will it feed power back through the switch and power the remaining cameras. As you can tell, I've never worked with a switch in the past. Haven't needed one.

Paul

 

[thiggins]

Each injector powers one device. The injector blocks any DC from going back into the switch, since it could damage the port.

 

[Pain]

I've just set up a small IP camera network using foscam units.

Foscam runs on 5v. What I finally decided to do is use an injector block with 5v camera adapters. The injector 'inserts' 12-24v into the network cable, and the adapter converts it down to 5v.

Here's the stuff I went with:

http://wifiqos.com/foscam.php

ADDED: If the cams you are looking at are true POE, then of course you won't need the 5v adapters. All you'd need is the injector an a 48v power supply. POE switches are sort of expensive so you may be better of to get an injector for how ever many cameras you need.

 

[Number 42]

My objective is to try to keep things neat and I don't like the thought of a bunch of these injectors on the Cat runs, so I'll probably go with the Foscam poe caneras and two Netgear GS108P switches. Some of the cameras will be in a different building (shop) so if I can limit it to max 4 cameras in either the house or shop, they should work for me.

 

[Pain]

In that link I gave you shows the 'injectors' aren't individual [unless you buy those] but are in a block, similar to the size of that netgear.

I understand your thoughts about keeping things neat. I almost went that direction myself and then realized that POE switches are limited to 100mb, at least the low end ones are. The cameras don't need more speed, and if you are only using the switches for the cameras then you're good to go.

 

[stevech]

PoE literally means IEEE 802.3af or 802.3at. These are expensive, 48V inserters with a protocol to negotiate voltage/current needs.

Consumer gear is rarely/never real PoE as above.

You can run 5V devices via power down the cat5 cable (not PoE). You simply use passive power inserters. There will be some voltage drop. With 5V devices, it's hard to deal with more than 25 ft or so of cable due to the voltage dropping from 5 to say 4.5V or less, and the device falters. You can calculate the drop vs. wire gauge vs. length, for using the two spare pairs for power in cat5. For 12V devices, there is less sensitivity.

There are a zillion inserters, such as
http://www.wlanparts.com/product/PO...hernet-inserters-for-POE-power-to-a-CAT5.html

see also
http://www.dslreports.com/forum/r24995010-voltage-drop-over-cat-5-calc-

SOmetimes, the right length of cat5 allows a 6VDC source to be used for a 5V device. But be careful not to exceed 5.1 or so... measured under load with current flowing. Without current flowing into the device, there's no "IR drop" (Ohm's law, E=IR)

 

[Pain]

Number 42. Be sure the Foscam cameras are 'real' POE cameras before you buy the switches. Seems when I was researching them I discovered they included an injector with the package, but I may have been looking at a different model. Just be sure you know what they are before you drop a bunch of money on the switches. Also, before you commit to a laptop you should play around with the cameras.

I currently have 5 IP cameras (that number will increase in time). I'm using geniusvision NVR software [it's free for home use up to 16 cameras] to support the cameras running on a dedicated Dual Core AMD Phenom II cpu at 3.4Ghz and it still utilizes around 50% of the cpu. That's doing motion detection on each camera. I have tried it on a quad core cpu of the same speed, and of course it runs about half of that utilization.

You can use the built in web interface on the cameras, but I've read it's not very reliable in terms of motion detection, email alerts, etc. I never tried it myself and went directly to a stand alone solution with NVR software. There are other software packages like Ispy and Blue Iris that are either free, or cheap.

I am building my setup to monitor construction of a house starting this summer, so I've got all my test cameras laying around my existing house and yard and plugged into my home network, or via wireless. It's been fun, but I've also had to adjust my expectations and configuration quite a bit from my initial idea of how I was going to run it and what hardware was needed to support it.

Stevech, the link I provided above shows the injector/adapter pairs that inject 12-24v on the switch end [depending on what power supply you use] and then the adapter converts that to 5v on the camera end, or you can also get 12 volt adapters, too. That arrangement will of course compensate for the voltage drop in the cat5. You are right, injecting 5v alone won't work very far.

Instead of getting a POE switch I just got an 8 port power injector and then I will use the 5v adapters at the camera end.

 

[Number 42]

The Foscam cameras I'm thinking of (http://foscam.us/outdoor-cameras/foscam-fi8905e-outdoor-poe-ip-camera.html) are said to be 802.3af compliant, so the PoE part should be OK. Thanks for the link to the Genius vision software, I'll check it out. Free is certainly a good price if it's a quality product.

The laptop I'm thinking of using is an Intel i3 processor running at 2.53 ghz. Sounds like it might be a little on the weak side.

 

[stevech]

Some of the popular NASes, such as Synology and QNAP, have NVR software. However, they charge a fee for other than a small number of cameras... assuming higher counts = professional use = more support costs.

 

[stevech]

Isn't it true that 1000BT (gigabit ethernet) uses all pairs in the cable? So there'd be no spares for a power inserter?

Just noted that because of the words at
http://foscam.us/active-poe-injector-98.html

 

[Pain]

Isn't it true that 1000BT (gigabit ethernet) uses all pairs in the cable? So there'd be no spares for a power inserter?

Just noted that because of the words at
http://foscam.us/active-poe-injector-98.html

Yep, that's true about the pairs. That what I was talking about in one of my posts above, that POE switches are only 100M, unless they have changed recently.

The cameras won't matter as they only use about 5Mb/s, but I just decided to use injectors for the cameras and have a regular gig switch for the rest of the network.

Some of the popular NASes, such as Synology and QNAP, have NVR software. However, they charge a fee for other than a small number of cameras... assuming higher counts = professional use = more support costs.

I was going to get a synology NAS for the NVR, and then after running the numbers I found the cost prohibitive and just built a new server and used it to run the cameras too.

 

[stevech]

Yep, that's true about the pairs. That what I was talking about in one of my posts above, that POE switches are only 100M, unless they have changed recently.

The cameras won't matter as they only use about 5Mb/s, but I just decided to use injectors for the cameras and have a regular gig switch for the rest of the network.

I was reacting to the web site for the inserter where it says it will work with 10/100/1000BT

 

[Pain]

Ah yeah, I see now. I think they are playing a little loose with the facts there unless there is something new I don't know about.

 

[Number 42]

Isn't it true that 1000BT (gigabit ethernet) uses all pairs in the cable? So there'd be no spares for a power inserter?

Just noted that because of the words at
http://foscam.us/active-poe-injector-98.html

If, and that's a big if, I understand the 802.3at standard, 1000 BT does use all 4 pairs for data and power is superimposed over the data on 2 of the pairs.

 

[matthelm]

POE doesn't need to be on it's own pair of wires. Ethernet uses an AC signal, and at each end has magnetics that isolate the signal. Because of this, you can inject a DC signal on the lines without effecting the AC signal (much). A POE device pulls the DC power off before the ethernet interface.