Newbie Question on development

D

Doorman352

Guest
How does one simulate an RS485 multi drop circuit for development? I am
trying to figure out how to simplify my design so I can simulate it, but
this critical piece is beyond my grasp.

Doorman352
 
On Wed, 05 May 2004 02:44:24 GMT, the renowned "Doorman352"
<doorman352@earthlink.net> wrote:

How does one simulate an RS485 multi drop circuit for development? I am
trying to figure out how to simplify my design so I can simulate it, but
this critical piece is beyond my grasp.

Doorman352
Click to expand...
You can buy inexpensive (<$100) adapters for a PC to change RS-232 to
RS-485. That might not have enough versatility to really wring out a
new design, but it's a start.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
Doorman352 wrote:
How does one simulate an RS485 multi drop circuit for development? I am
trying to figure out how to simplify my design so I can simulate it, but
this critical piece is beyond my grasp.
Click to expand...
Why simulate ?
At one point or another you actually have to run it.
Yes, there are cheap RS232 to RS485 converters.
There is one drawback, however.
For a true multipoint setup, the PC is too slow in
changing the direction of its RS485 driver.
This is improved in the RS422 setup, where the PC is always listening on
one pair and transmitting exclusively on the other, while the external
devices share the first pair for transmission to the PC.
This RS422 setup is perfect for a PC based master-slave setup.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
 
I would like to simulate my boards to determine if I can design/build a
working configuration before I start blowing up chips. I know I need to
build a prototype at some point, but I am trying to develop a circuit and do
as much work as I can while before I commit to specific chips, etc.

I am not considering using adapters.... so these aren't going to help.

Doorman352
 
Doorman352 wrote:

I would like to simulate my boards to determine if I can design/build a
working configuration before I start blowing up chips. I know I need to
build a prototype at some point, but I am trying to develop a circuit and do
as much work as I can while before I commit to specific chips, etc.

I am not considering using adapters.... so these aren't going to help.
Click to expand...
A working configuration ?
Why shouldn't it work ?
What do you have this far ?
Where are the problems ?

As to the line transceivers : DS75176 are common.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
 
Doorman352 wrote:

I would like to simulate my boards to determine if I can design/build a
working configuration before I start blowing up chips. I know I need to
build a prototype at some point, but I am trying to develop a circuit and do
as much work as I can while before I commit to specific chips, etc.

I am not considering using adapters.... so these aren't going to help.
Click to expand...
Your simulation is only as good as your models.
Most important on RS485, especially because of the length,
is the limited common mode range.
So, unless you exceed that, RS485/422 is trivial to work with.

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

I am trying to develop an interface by which I can set/read conditions
of various sensor or controls, as well as activate relays to start/stop
controls. I am by no means an electronics engineer, but I do have a working
knowledge of it.

I originally started with an 8 bit parallel bus and have since scraped
the idea because of cabling concerns, so I decided to work with serial. That
too is becomming a problem because I do not want to have to hire someone to
develop a software application to control my boards via serial ports. Hence
my desire to do modeling first to see if this is even something I can do.

Since the RS485 interfaces are going to be an integral part of my
design, I need to find out what *I* can and can't do with them.

My plan is to work in a virtual environment as much as possible so that
I can determine what works, and what does not with a minimal of material
waste. Since I have nothing hard wired, I can change my design as needed. So
that is why I am trying to find a way to model an RS485 chip.

Regards


Doorman352
 
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