Looking USB to RS-232 + RS-422/485 Module ?

Hi,

I need 2 simple Asyncronous serial ports on a laptop without any
serial ports. I have found many USB to RS-232 and a few USB to
RS-422/485 modules, but have not able to find a reasonably priced unit
that has one RS-232 port and one RS-422/485 port. We are currently
using a separate USB to RS-232 and USB to RS422/485, but the "COM"
port changes depending on the sequence in which they are plugged in.
This is for a test system where the people are fairly clueless, and I
want something that stays consistant.

Regards
  Anton Erasmus

Anton Erasmus wrote:

> Hi,
> 
> I need 2 simple Asyncronous serial ports on a laptop without any
> serial ports. I have found many USB to RS-232 and a few USB to
> RS-422/485 modules, but have not able to find a reasonably priced unit
> that has one RS-232 port and one RS-422/485 port. We are currently
> using a separate USB to RS-232 and USB to RS422/485, but the "COM"
> port changes depending on the sequence in which they are plugged in.
> This is for a test system where the people are fairly clueless, and I
> want something that stays consistant.

USB to RS232 is fairly standard, they go from 10 Euro up.
All you need is now an RS232 to RS422 converter. They are
rather simple to build.

Rene
-- 
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

"Anton Erasmus" <nobody@spam.prevent.net> wrote in message 
news:4h9pd25gmobmopos2ivgbv98vuin8iufn7@4ax.com...
> Hi,
>
> I need 2 simple Asyncronous serial ports on a laptop without any
> serial ports. I have found many USB to RS-232 and a few USB to
> RS-422/485 modules, but have not able to find a reasonably priced unit
> that has one RS-232 port and one RS-422/485 port. We are currently
> using a separate USB to RS-232 and USB to RS422/485, but the "COM"
> port changes depending on the sequence in which they are plugged in.
> This is for a test system where the people are fairly clueless, and I
> want something that stays consistant.
>
> Regards
>  Anton Erasmus

Maybe a PCMCIA card like the Sealevel 3623 ?

Hoss 

"Anton Erasmus" <nobody@spam.prevent.net> wrote in message 
news:4h9pd25gmobmopos2ivgbv98vuin8iufn7@4ax.com...
> Hi,
>
> I need 2 simple Asyncronous serial ports on a laptop without any
> serial ports. I have found many USB to RS-232 and a few USB to
> RS-422/485 modules, but have not able to find a reasonably priced unit
> that has one RS-232 port and one RS-422/485 port. We are currently
> using a separate USB to RS-232 and USB to RS422/485, but the "COM"
> port changes depending on the sequence in which they are plugged in.
> This is for a test system where the people are fairly clueless, and I
> want something that stays consistant.

When the are both plugged in goto the device manager of the computer and 
bring up the comm ports. There should be advanced properties and dig around 
and you should be able to change from auto to a specific com port so that it 
gets the same letter everytime.

If that doesnt seem to work get two 232 usbs and one converter, rs232 to 
rs485. Though this will likly require an external power pack. They are 
normally $50 to $99 though, it depends on how many things are on the rs485 
network, if its the full 32 then you need alot of power so the external 
power pack ones are always a good idea. 

Hi Anton,

I have units which feature an isolated RS-232, RS-422, or RS-485 port. 
The interfaces are wired in parallel so there is no need to select the 
mode, just use the DB-9 or the screw terminals.

  The units have unique serial numbers which means that windows will 
allow  more than one or two (I have stacked 5 or more) without getting 
confused or losing track of which serial port number it was assigned to 
it. Since these are single port units you would need two. Let me know if 
you are interested and I can email you the data short.

*Peter*



Anton Erasmus wrote:
> Hi,
> 
> I need 2 simple Asyncronous serial ports on a laptop without any
> serial ports. I have found many USB to RS-232 and a few USB to
> RS-422/485 modules, but have not able to find a reasonably priced unit
> that has one RS-232 port and one RS-422/485 port. We are currently
> using a separate USB to RS-232 and USB to RS422/485, but the "COM"
> port changes depending on the sequence in which they are plugged in.
> This is for a test system where the people are fairly clueless, and I
> want something that stays consistant.
> 
> Regards
>   Anton Erasmus

On Fri, 11 Aug 2006 19:50:13 +0200, Rene Tschaggelar <none@none.net>
wrote:

>Anton Erasmus wrote:
>
>> Hi,
>> 
>> I need 2 simple Asyncronous serial ports on a laptop without any
>> serial ports. I have found many USB to RS-232 and a few USB to
>> RS-422/485 modules, but have not able to find a reasonably priced unit
>> that has one RS-232 port and one RS-422/485 port. We are currently
>> using a separate USB to RS-232 and USB to RS422/485, but the "COM"
>> port changes depending on the sequence in which they are plugged in.
>> This is for a test system where the people are fairly clueless, and I
>> want something that stays consistant.
>
>USB to RS232 is fairly standard, they go from 10 Euro up.
>All you need is now an RS232 to RS422 converter. They are
>rather simple to build.

The RS-232/422 conversion is trivial, but if RS-232/485 conversion is
required, the converter becomes quite complex. Don't expect to be able
to use RTS data direction control over USB (or Ethernet), since the
latencies even in direct PCI connection with software RTS data
direction control are often too long.

Paul

Paul Keinanen wrote:
> The RS-232/422 conversion is trivial, but if RS-232/485 conversion is
> required, the converter becomes quite complex. Don't expect to be able
> to use RTS data direction control over USB (or Ethernet), since the
> latencies even in direct PCI connection with software RTS data
> direction control are often too long.

I always use a small dedicated micro to handle the line turn-around in 
RS-485 interfaces. When the control micro is locked to the baud rate it 
is possible to have a very tight line turn-around which I usually set to 
be around 2 bits.

*Peter*

Peter Jakacki wrote:
> Paul Keinanen wrote:
> 
>> The RS-232/422 conversion is trivial, but if RS-232/485 conversion is
>> required, the converter becomes quite complex. Don't expect to be able
>> to use RTS data direction control over USB (or Ethernet), since the
>> latencies even in direct PCI connection with software RTS data
>> direction control are often too long.
> 
> 
> I always use a small dedicated micro to handle the line turn-around in 
> RS-485 interfaces. When the control micro is locked to the baud rate it 
> is possible to have a very tight line turn-around which I usually set to 
> be around 2 bits.

This means the micro understands the protocol.

Rene
-- 
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

On Fri, 11 Aug 2006 19:50:13 +0200, Rene Tschaggelar <none@none.net>
wrote:

>Anton Erasmus wrote:
>
>> Hi,
>> 
>> I need 2 simple Asyncronous serial ports on a laptop without any
>> serial ports. I have found many USB to RS-232 and a few USB to
>> RS-422/485 modules, but have not able to find a reasonably priced unit
>> that has one RS-232 port and one RS-422/485 port. We are currently
>> using a separate USB to RS-232 and USB to RS422/485, but the "COM"
>> port changes depending on the sequence in which they are plugged in.
>> This is for a test system where the people are fairly clueless, and I
>> want something that stays consistant.
>
>USB to RS232 is fairly standard, they go from 10 Euro up.
>All you need is now an RS232 to RS422 converter. They are
>rather simple to build.

I have separate USB to RS-232 and USB to RS-422. The problem is that
depending on which ports the devices are plugged in, or in which
sequence the COM port changes. I have found USB to 2 and more RS-232
ports, but not to a mixture of RS-232 and RS-422/485 ports. I do not
need the multidrop functionality of RS-485. I am using full duplex
comms.

Regards
  Anton

On 2006-08-12, Anton Erasmus <nobody@spam.prevent.net> wrote:

> I have separate USB to RS-232 and USB to RS-422. The problem
> is that depending on which ports the devices are plugged in,
> or in which sequence the COM port changes.

And you've been told how to fix that.  Didn't it work?  I know
you can fix that easily under Linux -- all of my USB serial
ports show up with pre-configured device names no matter what
order I plug them in.

> I have found USB to 2 and more RS-232 ports, but not to a
> mixture of RS-232 and RS-422/485 ports. I do not need the
> multidrop functionality of RS-485. I am using full duplex
> comms.

-- 
Grant Edwards                   grante             Yow!  I brought my BOWLING
                                  at               BALL -- and some DRUGS!!
                               visi.com