Using Multiple USB to RS-485 Adaptors

[kychristmas]

Personally, I use a Moxa 4-Port RS-485 card, but I recently ordered a Bulk-Lot of USB to RS485 converters for when the Connection Frenzy happens. The idea is to have a Converter that is pre-configured, wired, and tested for Renard so that the user can just plug in a straight through Cat-5 cable between the adaptor and the first Renard.

I had been asked about using multiples...

Can someone that uses one of these tell me if it is possible to use more than one of these simultaneously? Meaning, have get two or more RS-485 using multiples of these? In theory, it should work, but relying on theory is the same as assuming.


Kelly

[chelmuth]

My experience with the USB-485 Dongles is about 2 minutes old. But with that said as far as I can tell they are just like the USB-RS-232 Dongles.. I would say it's possible to use multiples.. The only caviat being that when you put one in a different USB port.. It changes Com port numbers.. IE.. I plugged the same dongle in to each of my USB ports on the computer and each time it came up as a different Com Port.. ie. Com4,5,6,7.. Now if I were to plug a different one in and do the same thing it would end up being 8,9,10,11.. So it will work people will just have to be concious of what they are plugging where.. if they accidently move or reverse them while moving something windows will add additional Com ports instead of re-activating the currently assigned ports. ie if I had 4 and they were arranged as 1,2,3,4.. If I accidently unplugged or reversed 2 of them it could end up looking like 1,3,5,6.. in this example I reversed what was origianally 2 and 4 and windows made new ports 5,6.. So in short it will work, but you have to be aware of what is happening and what you assign ports to in Vixen and understand how it could possible change.. where as the moxa cards are always in the same spot everytime.

Edit : Additionally it is possible to change them around manually in the device manager. If someone is comfortable enough to do it.. it's under the advanced settings for the com options.

[kychristmas]

That makes sense given that USB ports are essentially a big hub and there's really only one USB plane (for lack of the correct term).

Since someone asked, I wanted to know. I'll stick with my Moxa PCI card. Multiples would definitely not be something that I suggest or recommend for a new users anyway.

[ErnieHorning]

You can have up to 31 USB devices per controller. Most computers have at least two USB controllers. If you have anything inside the case that’s connected to the bus, it will be included in the total. The number of USB port connectors, is not the number of controllers. You may have 6 ports and only one controller.

[griffixdc]

if you read the "rs485 help" thread i started it explains that in there... it also explains that you cant essentially do it because the com port addressing wouldn't work it would send duplicate data to each split usb channel not different data ( like we want) ....but maybe if you can program a driver to recognize new ports from a port being split into multiple channels of ports then maybe it would work...but i have zero idea how to do that.

[dlovely]

if you read the "rs485 help" thread i started it explains that in there... it also explains that you cant essentially do it because the com port addressing wouldn't work it would send duplicate data to each split usb channel not different data ( like we want) ....but maybe if you can program a driver to recognize new ports from a port being split into multiple channels of ports then maybe it would work...but i have zero idea how to do that.

Will actually work just fine. Each USB->Serial adapter will get a individual port address and show up in the system as COM#. No data ever gets split this way. USB specifications allow hubs to allow multiple USB devices, this has no affect on the RS485 data coming out of the converter.

[kychristmas]

You can have up to 31 USB devices per controller. Most computers have at least two USB controllers. If you have anything inside the case that’s connected to the bus, it will be included in the total. The number of USB port connectors, is not the number of controllers. You may have 6 ports and only one controller.

That I didn't know. I assumed it was one controller. I added a USB 2.0 Card to an old Laptop that only had USB 1. That was the first time that I remember seeing multiple USB Controllers in the Device Manager.

[griffixdc]

Will actually work just fine. Each USB->Serial adapter will get a individual port address and show up in the system as COM#. No data ever gets split this way. USB specifications allow hubs to allow multiple USB devices, this has no affect on the RS485 data coming out of the converter.

ok never tried it out, just explaining what was explain to me :)....although my desktop computer has 6 usb ports and only 4 show up in the drivers info but i can use all 6 successfully, can you explain that ? it it bewilders me. trying to assign a usb to parallel cable to bring my laserjet printer up and running.

[dlovely]

ok never tried it out, just explaining what was explain to me :)....although my desktop computer has 6 usb ports and only 4 show up in the drivers info but i can use all 6 successfully, can you explain that ? it it bewilders me. trying to assign a usb to parallel cable to bring my laserjet printer up and running.

You were wanting to split the 485 signal AFTER the adapter. That will just duplicate the data as the computer has only 1 port. Now when you put in a additional adapter you get an additional port to output data on from Vixan. No splitting signals so all data is original.

[griffixdc]

You were wanting to split the 485 signal AFTER the adapter. That will just duplicate the data as the computer has only 1 port. Now when you put in a additional adapter you get an additional port to output data on from Vixan. No splitting signals so all data is original.

ok heres my stupid question but it will help me learn.....so can i take a usb splitter 1 port in 4 out and then use that to have 4 different ports to feed different cables to rs485 converters while also having 4 separate signals not 4 duplicate signals?

[dlovely]

ok heres my stupid question but it will help me learn.....so can i take a usb splitter 1 port in 4 out and then use that to have 4 different ports to feed different cables to rs485 converters while also having 4 separate signals not 4 duplicate signals?

It is referred to as a USB Hub. If you plugged 4 different USB to Serial adapters into the USB Hub it would work. The 'ports' on a USB Hub are not 485 out, so you still need multiple adapters.

[griffixdc]

It is referred to as a USB Hub. If you plugged 4 different USB to Serial adapters into the USB Hub it would work. The 'ports' on a USB Hub are not 485 out, so you still need multiple adapters.

well i think i got it but i wont repeat that knowledge until i test it ;)

[kychristmas]

ok heres my stupid question but it will help me learn.....so can i take a usb splitter 1 port in 4 out and then use that to have 4 different ports to feed different cables to rs485 converters while also having 4 separate signals not 4 duplicate signals?

A "Splitter" and "Hub" are completely different things. This is why you can simply add more USB ports to your computer by adding a "HUB" they usually come in 4 and 6 port. My work computer has 12 ports total becaue of the various USB devices that also contain USB Hubs. I just realized this morning that my Keyboard has 3 USB ports in it.

My original question was more about whether the drivers for these converters can be configured seperately allowing for different port assignments. Sometimes this cheap chinese stuff is very Brute force. It looks like they are. The USB conversation was just bonus learning :)

[dlovely]

My original question was more about whether the drivers for these converters can be configured seperately allowing for different port assignments. Sometimes this cheap chinese stuff is very Brute force. It looks like they are. The USB conversation was just bonus learning :)

I cannot speak for the cheap or new ones, but the old Belkin ones I've used allow multiple to be plugged in each configured to its own serial address. As Cory said, they tend to change port numbers with multiples when re-added, but you can go to the device manager and override that. I have a few IP Serial port adapters from Sena I was going to try out. Altho someone posted they might not work great.

[dmoore]

How many channels do you have in your display or are you planning for in 2011?

[griffixdc]

How many channels do you have in your display or are you planning for in 2011?

who are you asking?

[kychristmas]

How many channels do you have in your display or are you planning for in 2011?

If you are asking me, I will have a few more than I had this year. Around 300, but that's not why I'm asking. I already have a Moxa 4-Port card so I'm in good shape. I run 3 hard-wired ports and then the 4th goes to a Ren-Wireless transmitter (Athough I didn't use it this year)

I was asking because it came up when I was helping someone else and I was just ordered a dozen of the Chinese converters.

[oldcqr]

FYI.....

2 years ago I used USB adapters and every couple of days I would get the dreaded Vixen 'unable to open port' crash. This year I switched to real rs232 ports (via a PCI card), and did not have the problem again.

I also ran 2 separate networks on 1 CAT 5, but that's a different post :)

[RickeyS]

I used three usb>RS485 adapters this year from one computer (they all were radio shack ones), reason why was, one I used a RW for a wireless part of my display and the other two went in two different directions which saved me a lot of cat 5 wires to run. Again I had them so it just made it easier to set up my display, all worked great.
Rick