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USB to many RS232 ports

June 26, 2013 | 6:54 am

hi ,
i’m about to need a good USB to Serial interface , and i would like many outputs .
16 is the maximum i can get from what i can find on the net .
i don’t know if i could be able to plug 2 interfaces like this , on a USB hub ,and have 32 outputs.
have some of you already worked on a set-up looking like this ?
i can see a "startech" one , which is not too expensive .

http://www.compufirst.com/fr/tous%2Dnos%2Dproduits/reseau/accessoire%2Dreseau/StarTech%2Ecom/HubAdaptateurFTDIUSB2%2E0vers16PortsSérieRS232%2DMontageenRack%2DMultiplexeur%2D1xUSBBFemelle%2D16xDB%2D9Mâle/fiche_prod.do?prodId=591269&appTreeId=43121&drtf=ga91%2D01&gclid=CL2UrcK5_7cCFXMdtAodB30A0Q#fiche_technique

have you already experienced 16 outputs , flawlessly ?
the used bauldrate will be 4800 …

thanks for your advices
Matthieu


June 27, 2013 | 1:53 am

i have contacted Startech , they say i should be able to "stack" (correct ?) two of these devices on a USB Hub and get all these outputs available ,
would be great !
if anyone had alternative (hardware or DIY) options ,
i would also be curious to hear about it …
Matthieu


June 27, 2013 | 8:32 pm

Hi Matthieu,
I’ve used Ethernet-to-Serial device servers many times for a wide variety of purposes. Looks like its more expensive all around, but very robust and fast. The other advantage is that you can locate the device server further away then with USB, not to mention control it remotely from another location all together. The companies I’ve used in the past are Moxa and SeaLevel. Both make USB-to-Serial Servers as well as Ethernet-to-Serial Severs up to 16 ports. The prices are around double what you’ve been finding from your source, but at least I can vouch for the quality and reliability. I’m currently using jit.net.send to send Jitter matrices at high speed (230400 baud) data to an RS485 8 port Ethernet-to-Serial device server in an LED display application.
I think your solution would be fine but my gut tells me that an Ethernet-to-Serial solution would scale better, but at a considerably higher price. With the USB solution you have 32 serial objects to manage, with the Ethernet solution you have two objects (one for each 16 port server) sending out all the data but the added complexity of figuring out how to format the TCP/IP information in the way the device server wants it. (This may be easy, I actually haven’t done it – the application I mentioned uses some custom firmware on the Device Server side to read and parse the jit.net.send packets)
good luck!, -bob


June 29, 2013 | 1:50 pm

Thanks a lot Bob ,
the USB to serial hub has just been ordered (i couldn’t have paid more) .
i had noticed the Moxa Brand (and its price ) , but hadn’t really had a look on the ethernet ones .i sure see , now , the advantages (particularly distance cables …)
i’ll keep in mind what you’ve just said , that’s the expensive but strong way ,very good to know it .
for the moment , i’m working with devices that are built to work at 4800 baud (90′s displays) ,and i can’t refresh them more than 1 time in ~2 seconds .
i suppose i would’nt need faster serial server , without modifying my devices ‘ electronics itself (please , life , let me do this later ,i need sun) .
i have planned to try this , but really later .then maybe i would reach the limits of the startech hub ?
i’ll report how the Startech ‘s working (at this speed it HAS to work good).

Thanks again Bob for sharing ,
Matthieu


July 8, 2013 | 10:57 am

hi ,
so i’ve been working a little with it ,
it seems to handle the 16 channels without any problem ,
but , and i’m quite amazed about it ,
as i unplug and plug back the device ,
the serial ports don’t appear in the same order ,
meaning that i have to re-link my patch’s outputs each time i open it ,
it even seems that the 16 names of the 16 ports are applying to different outputs ,
randomnly ,at each launch .
that is serious crap !
i’ll try to deal with it , … strange …

Matthieu


September 21, 2013 | 4:28 pm

so ,
everything ‘s now running fine , and the re-linking problem has been solved .
i just had to set the port using "port" message , followed by the name of the port,
instead of using the "serport" attribute , followed by the number …

so , i would just say it’s a good serial interface .
and , by far , the cheapest .

cheers
Matthieu


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