Matrix Switch 5x8 +/-10V

J

Jens Bretschneider

Guest
Hi,

I'm looking for a matrix switch IC which is able to handle the voltage of a
serial (RS232/V24) connection (+/- 10 V should be enough).

All I've found so far is the MT8808
http://www.alldatasheet.com/datasheet-pdf/pdf/MITEL/MT8808.html
but it doesn't support negative voltage.

Any Hints?

What I want to create is a software-configurable break-out-box for a serial
port, to use only *one* cable to connect to many different devices (routers,
switches etc.).

USB2RS232-IC (TUSB3410) <-> DRIVER/RECEIVER (MAX232) <-> 5x8 Matrix Switch
(???) <-> RJ45-Plug <-> DB9/25-converter (if necessary)

(5x8 because 4x RS232 + 1x Gnd to 8x RJ45)

Any help is greatly appreciated! :)
Jens
 
"Jens Bretschneider" <news@jens-bretschneider.de> wrote in message
news:2r2thfF158ls1U1@uni-berlin.de...
Hi,

I'm looking for a matrix switch IC which is able to handle the voltage
of a
serial (RS232/V24) connection (+/- 10 V should be enough).
Click to expand...
The standard for RS-232 or EIA-232 is much higher than that, plus or
minus 25V in this URL.
http://www.lammertbies.nl/comm/info/RS-232_specs.html Since it's
unbalanced it can have much higher voltages if there is a problem with
grounding.

All I've found so far is the MT8808
http://www.alldatasheet.com/datasheet-pdf/pdf/MITEL/MT8808.html
but it doesn't support negative voltage.

Any Hints?
Click to expand...
If you're wise, you will stay away from electronic switching and use
relays to switch the RS-232 signals. These can be easily controlled
from your parallel port.

This stray currents problem is especially important if you plan on
having the cables from the devices more than a few meters from your PC.

Another solution you might consider is wire ORing all the devices. If
they are 'slaves', they don't put put out data unless they are asked to,
then just wire OR all their TXDs to your PC's RXD, and switch your PC's
TXD among their RXDs. Do all the switching *before* you send the data
to the MAX232 drivers. That way, everything will be TTL logic levels.
You can do it *so* much easier that way.


What I want to create is a software-configurable break-out-box for a
serial
port, to use only *one* cable to connect to many different devices
(routers,
switches etc.).

USB2RS232-IC (TUSB3410) <-> DRIVER/RECEIVER (MAX232) <-> 5x8 Matrix
Switch
(???) <-> RJ45-Plug <-> DB9/25-converter (if necessary)

(5x8 because 4x RS232 + 1x Gnd to 8x RJ45)

Any help is greatly appreciated! :)
Jens
Click to expand...
 
Hi again,

The standard for RS-232 or EIA-232 is much higher than that, plus or
minus 25V in this URL.
http://www.lammertbies.nl/comm/info/RS-232_specs.html Since it's
unbalanced it can have much higher voltages if there is a problem with
grounding.
Click to expand...
Yes, that's right, but:
* the MAX232 will only drive +/- 10 V outgoing
* I've seen some schematics where the incoming level is limited with a ~9V6
Zener Diode and a resistor

If you're wise, you will stay away from electronic switching and use
relays to switch the RS-232 signals. These can be easily controlled
from your parallel port.
Click to expand...
No way... I want to use an USB2RS232-Converter to be independant of legacy
ports. And 5x8 = 40 relais is not really an option for a handy console cable
for a service technician "on the road"... ;-)

This stray currents problem is especially important if you plan on
having the cables from the devices more than a few meters from your PC.
Click to expand...
I think 2 meters would be enough.

Another solution you might consider is wire ORing all the devices. If
they are 'slaves', they don't put put out data unless they are asked to,
then just wire OR all their TXDs to your PC's RXD, and switch your PC's
TXD among their RXDs. Do all the switching *before* you send the data
to the MAX232 drivers. That way, everything will be TTL logic levels.
You can do it *so* much easier that way.
Click to expand...
No, that's impossible: the goal is to have a flexible pinout on the end to
the (router-)device, so I have to do the switching between the drivers and
the device. Else I don't know which way around to put the MAX232-drivers
into the connections, because I don't know which one is a transmitting and
which one is a receiving line.

Jens
 
"Jens Bretschneider" <news@jens-bretschneider.de> wrote in message
news:2r347gF15stl7U1@uni-berlin.de...
Hi again,

The standard for RS-232 or EIA-232 is much higher than that, plus or
minus 25V in this URL.
http://www.lammertbies.nl/comm/info/RS-232_specs.html Since it's
unbalanced it can have much higher voltages if there is a problem
with
grounding.

Yes, that's right, but:
* the MAX232 will only drive +/- 10 V outgoing
* I've seen some schematics where the incoming level is limited with a
~9V6
Zener Diode and a resistor

If you're wise, you will stay away from electronic switching and use
relays to switch the RS-232 signals. These can be easily controlled
from your parallel port.

No way... I want to use an USB2RS232-Converter to be independant of
legacy
ports. And 5x8 = 40 relais is not really an option for a handy console
cable
for a service technician "on the road"... ;-)

This stray currents problem is especially important if you plan on
having the cables from the devices more than a few meters from your
PC.

I think 2 meters would be enough.

Another solution you might consider is wire ORing all the devices.
If
they are 'slaves', they don't put put out data unless they are asked
to,
then just wire OR all their TXDs to your PC's RXD, and switch your
PC's
TXD among their RXDs. Do all the switching *before* you send the
data
to the MAX232 drivers. That way, everything will be TTL logic
levels.
You can do it *so* much easier that way.

No, that's impossible: the goal is to have a flexible pinout on the
end to
the (router-)device, so I have to do the switching between the drivers
and
the device. Else I don't know which way around to put the
MAX232-drivers
into the connections, because I don't know which one is a transmitting
and
which one is a receiving line.

Jens
Click to expand...
Right. Well, Good Luck.
 
On Sat, 18 Sep 2004 15:58:27 +0200, "Jens Bretschneider"
<news@jens-bretschneider.de> put finger to keyboard and composed:

Hi,

I'm looking for a matrix switch IC which is able to handle the voltage of a
serial (RS232/V24) connection (+/- 10 V should be enough).

All I've found so far is the MT8808
http://www.alldatasheet.com/datasheet-pdf/pdf/MITEL/MT8808.html
but it doesn't support negative voltage.

Any Hints?

What I want to create is a software-configurable break-out-box for a serial
port, to use only *one* cable to connect to many different devices (routers,
switches etc.).

USB2RS232-IC (TUSB3410) <-> DRIVER/RECEIVER (MAX232) <-> 5x8 Matrix Switch
(???) <-> RJ45-Plug <-> DB9/25-converter (if necessary)

(5x8 because 4x RS232 + 1x Gnd to 8x RJ45)

Any help is greatly appreciated! :)
Jens
Click to expand...
Use additional RS232 driver/receiver ICs for each of the eight
devices, and select the desired device using a one-of-eight decoder.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
 
Hi,

USB2RS232-IC (TUSB3410) <-> DRIVER/RECEIVER (MAX232) <-> 5x8 Matrix Switch
(???) <-> RJ45-Plug <-> DB9/25-converter (if necessary)

(5x8 because 4x RS232 + 1x Gnd to 8x RJ45)


Use additional RS232 driver/receiver ICs for each of the eight
devices, and select the desired device using a one-of-eight decoder.
Click to expand...
I think you misunderstood my question: There is only *one* RJ45 plug with 8
wires. Each of the 8 wires can be any of the RS232 signals (TxD, RxD, RTS,
CTS, ...). Different devices use different pinouts on the RJ45 plug. The
goal is to make the pinout of the RJ45 plug configurable to support these
different devices with only one cable.

Jens
 
On Sun, 19 Sep 2004 23:02:48 +0200, "Jens Bretschneider"
<news@jens-bretschneider.de> wrote:

Hi,

USB2RS232-IC (TUSB3410) <-> DRIVER/RECEIVER (MAX232) <-> 5x8 Matrix Switch
(???) <-> RJ45-Plug <-> DB9/25-converter (if necessary)

(5x8 because 4x RS232 + 1x Gnd to 8x RJ45)


Use additional RS232 driver/receiver ICs for each of the eight
devices, and select the desired device using a one-of-eight decoder.

I think you misunderstood my question: There is only *one* RJ45 plug with 8
wires. Each of the 8 wires can be any of the RS232 signals (TxD, RxD, RTS,
CTS, ...). Different devices use different pinouts on the RJ45 plug. The
goal is to make the pinout of the RJ45 plug configurable to support these
different devices with only one cable.

Jens
Click to expand...

I see two easy solutions to your problem:

1. have 8 RJ45 sockets on your device, wired so that the 8 sockets
cover all possibilities - the user just has to plug the remote device
into the correct socket.

2. have a single RJ45 socket, and a selection of adaptor cables.

Either solution will be much easier (and probably more reliable) than
creating a complex switching system.

If you really feel you must create this switching system, the thing
you need to search for (at Maxim or elsewhere) is "Analog switch".




--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
 
Dear Jens,

You need some CD4051 (1/8 analog mux, not the HC74 types!), which
can be supplied with +/- 8V (should withstand +/- 9V).
Additionally you have to limit the input voltage range to this level,
which is easily done with a bunch of diodes and some resistors.

Every RS-232 device must be able to function with +/- 5V levels.

HTH
Wolfgang

--
From-address is Spam trap
Use: wolfgang (dot) mahringer (at) sbg (dot) at
 
Wolfgang posted:

<< Dear Jens,

You need some CD4051 (1/8 analog mux, not the HC74 types!), which
can be supplied with +/- 8V (should withstand +/- 9V).
Additionally you have to limit the input voltage range to this level,
which is easily done with a bunch of diodes and some resistors.

Every RS-232 device must be able to function with +/- 5V levels.
That *RS-232* is going to confuse a lot of people.

As I recall, RS-232 (Recommended Standard) specifies +/- 20V.

+/- 5V isn't specified until ANSI TIA 232-D,and also by ETSI, but I don't
recall the number.

If you mean new designs of the "232" interface *should* be at +/- 5V, you
should refer to the ANSI Standard or the ETSI Standard.

Don
 
Hi Don,

Dbowey wrote:

Wolfgang posted:

[...]
Every RS-232 device must be able to function with +/- 5V levels.

That *RS-232* is going to confuse a lot of people.

As I recall, RS-232 (Recommended Standard) specifies +/- 20V.
Click to expand...
As I recall, there a specified transmitter voltage level, and
a minimum receiver voltage level, which IIRC is +/- 3V (!).

+/- 5V isn't specified until ANSI TIA 232-D,and also by ETSI, but I don't
recall the number.
Click to expand...
Since the OP needs that for a testing device and not for a
high volume product, this point is totally irrrelevant.

If you mean new designs of the "232" interface *should* be at +/- 5V, you
should refer to the ANSI Standard or the ETSI Standard.
Click to expand...
No, you have misunderstood me. Sender should have +/- 12V (or whatever),
but receivers must be able to correctly detect +/- 3V.

HTH
Wolfgang

--
From-address is Spam trap
Use: wolfgang (dot) mahringer (at) sbg (dot) at
 
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