chuckd Posted September 11, 2009 Share Posted September 11, 2009 A quick question here. As I'm about to implement over 1000 LOR channels on four separate USB to RS485 connections, I'm wondering about the best implementation for this.Previously, I've been using a high performance laptop that only has one USB port. I was thinking of either using a high performance USB hub, or buying another computer with multiple USB ports built in. Is there really any difference, or does a computer with multiple USB ports simply only have an internal USB hub?Thanks in advance,Chuck Link to comment Share on other sites More sharing options...
-klb- Posted September 11, 2009 Share Posted September 11, 2009 That depends, and the manufacturers often don't say much. From the device manager, you can tell a bit. I think my laptop has two USB ports, one of which is hubbed to two external ports. I think my previous desktop had three USB ports, one of them hubbed out to four ports, and the other two were independent ports. Then the next step that I never investigated was what it took to tell which port was on the hub, or an independent port. Link to comment Share on other sites More sharing options...
vipzach Posted September 11, 2009 Share Posted September 11, 2009 It would be much cheaper to try the USB hub vs a new laptop. Link to comment Share on other sites More sharing options...
cmoore60 Posted September 11, 2009 Share Posted September 11, 2009 Actually with 1000 channels that will run on one USB network.However, if you go with a hub, make sure it is a powered up. The USB adapters are powered from the computer side and if you do not use a powered hub then you will probably overload the power on the port. Link to comment Share on other sites More sharing options...
-klb- Posted September 11, 2009 Share Posted September 11, 2009 Also, I keep forgetting to check which mode these USB adapters run in. Even if it is USB1.1 full speed, that would imply that you have all the adapters on the hub sharing 12Mbps, and 4 networks at the highest speed won't eat into that at all. If they run in a lower speed mode, with most hubs, they will all share the bandwidth of that slower speed. Belkin makes a USB hub that is more like an ethernet switch, in that it will communicate with the PC at the fastest speed the PC port supports, and then communicate with each of the USB peripherals at their optimal speed. With something like this, using its power supply, I would think there would be zero issues sharing one port.http://www.everythingusb.com/hardware/index/Belkin_TetraHub_Hi-Speed_USB_2.0_4-Port_Hub.htm Link to comment Share on other sites More sharing options...
chuckd Posted September 11, 2009 Author Share Posted September 11, 2009 Assuming USB 1.1 (12 Mbps), if I used a USB hub to connect to 4 separate networks, I could only run each network at a theoretical maximum of 3 Mbps. However, if the PC had 4 separate USB ports that were NOT simply hubbed inside, they would each run independently at 12 Mbps (again, theoretical).Of course, I know LOR will run 1000+ channels on one network, but as we all know, you get slow-downs when trying to do a lot of fancy stuff with this many channels (and I indeed did have slow-downs last year).I'd just like to solve this problem once and for all. However, it sounds like it could be next to impossible to determine if a multi-USB port PC does indeed have separate controllers, or an internal hub.How I miss the hold days when PC's came with schematics! Link to comment Share on other sites More sharing options...
Denny Posted September 11, 2009 Share Posted September 11, 2009 I have seen cards that can be installed with multiple serial ports, some with up to 8 ports. Would this be any better than the USB hub? Link to comment Share on other sites More sharing options...
-klb- Posted September 11, 2009 Share Posted September 11, 2009 Better than a basic hub. The hub reviewed in the link I posted above has been reviewed as being as good in most cases as a multi port card. Link to comment Share on other sites More sharing options...
chuckd Posted September 11, 2009 Author Share Posted September 11, 2009 The Belkin hub you suggested works that way IF the main USB connection to the PC is a USB 2.0 connection, correct? I'm fairly certain that my laptop has USB 2.0 connections, so that may be exactly what I'm looking for.Thanks for the advice. That hub is definitely cheaper than a new computer. Link to comment Share on other sites More sharing options...
-klb- Posted September 11, 2009 Share Posted September 11, 2009 The belkin links to the PC at the highest mode the PC port suggests, and each individual port runs at the speed the connected device supports. Unlike most hubs where all ports have to run the same speed as the least capable device. If the USB adapters happen to run less than USB 1.1 full speed, you would come out ahead with this hub on a PC port that could only run USB 1.1 full speed. And with a PC port that runs USB 2.0 high speed, you should definitely get optimal results. Link to comment Share on other sites More sharing options...
Jack Stevens Posted September 12, 2009 Share Posted September 12, 2009 There's a fairly simple way to check for 1.1 or 2.0; plug in a new memory stick or external hard drive. If you get the prompt "This device can run faster....." you have a 1.1 port.I have a laptop with a docking station; the laptop itself has two USB 2.0 ports, the docking station has 2 USB 1.1 ports. Unfortunately, the docking station gets in the way of the laptop ports.If it's a 1.1 port in your laptop, perhaps an multi-port USB PC-MCIA card would correct this issue. A PC-MCIA card should give you another root hub anyway, so it'd be something to consider, even if the factuory-supplied ports are 2.0. Check your device manager for root hubs and Generic USB hubs to know what you currently have. Link to comment Share on other sites More sharing options...
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