"Glen Wiley Wilson" wrote in message
news
snip

If you select a multiplexor, make
sure it has the isolation feature. I believe that Meindert's have
this.

That's right. And beware of the new 'improved' model of Noland: this one has
NO galvanic isolation.

To make it more complex, not all NMEA instruments are actually using
RS-422. For instance, my Garmin handheld actually uses RS-232 and has
a typical serial port connector, so no convertor is necessary. My
depth sounder and knotlog seem to be using some sort of hybrid. My
autopilot is an honest to gosh RS-422 interface. When you look at the
wiring instructions, if you see a +, a ground, and a signal wire, you
aren't looking at RS-422. If you see a +, a ground, a signal +, and a
signal -, you have an RS-422. Again, I would never hook an RS-422 and
an RS-232 circuit together directly. Your mileage may vary.

In general: you can connect a RS-232 output to a NMEA RS-422 input by
connecting teh TX or OUT from the RS-232 to the + or 'A' from an NMEA in,
while connecting the - or B from NMEA in to the ground of teh RS-232 output.
The other way around (RS-422 out to RS-232 in) will mosty not work.

Meindert

On Wed, 22 Oct 2003 09:19:20 +0200, "Meindert Sprang"
tempted fate with:

"Glen Wiley Wilson" wrote in message
news
Again, I would never hook an RS-422 and
an RS-232 circuit together directly. Your mileage may vary.

In general: you can connect a RS-232 output to a NMEA RS-422 input by
connecting teh TX or OUT from the RS-232 to the + or 'A' from an NMEA in,
while connecting the - or B from NMEA in to the ground of teh RS-232 output.
The other way around (RS-422 out to RS-232 in) will mosty not work.

Meindert

Yes, I have seen or done both. I even understand why it works that
way. I was merely stating a policy. When I spec something for
navigating a boat it has to be bulletproof, not a marginal "generally
works" type of thing.

Also, I don't like connecting anything to a ground except another
ground. Seems to me to be asking for several different kinds of
trouble. I am not any kind of an engineer, whereas I believe you are,
but that is my policy. As I said, other peoples's mileage may vary,
but I suspect we are more or less in agreement, or your products would
not be what they are.

On a different subject, do you know what's going on with NMEA2000?
Did it wind up being CAN, and is anyone supporting it yet? It looks
like a sweet deal for the instrument makers. RS-232/CAN convertors
are 3 times the price of RS-422/RS-232 and it looks as if they could
potentially lock out anyone who doesn't pony up the fee to get an ID
assigned. But maybe I'm just paranoid...




__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at worldwidewiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

On Wed, 22 Oct 2003 14:02:52 GMT, "Glen Wiley Wilson"
tempted fate with:

On Wed, 22 Oct 2003 09:19:20 +0200, "Meindert Sprang"
tempted fate with:

"Glen Wiley Wilson" wrote in message
news
Again, I would never hook an RS-422 and
an RS-232 circuit together directly. Your mileage may vary.

In general: you can connect a RS-232 output to a NMEA RS-422 input by
connecting teh TX or OUT from the RS-232 to the + or 'A' from an NMEA in,
while connecting the - or B from NMEA in to the ground of teh RS-232 output.
The other way around (RS-422 out to RS-232 in) will mosty not work.

Meindert

Yes, I have seen or done both. I even understand why it works that
way. I was merely stating a policy. When I spec something for
navigating a boat it has to be bulletproof, not a marginal "generally
works" type of thing.

I forgot to mention that NMEA listeners are supposed to be isolated,
so it should be perfectly fine to attach an RS-232 talker to an NMEA
listener. I'm just not sure everyone implemented that particular
feature, given the workmanship I've seen in the instruments I've
cracked open. So, for the record, when speaking for public
consumption, I prefer to play it safe.

But, as I said before, I'm not an expert and I'm willing to be
educated if I'm wrong.

__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at worldwidewiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

"Glen Wiley Wilson" wrote in message
...

I forgot to mention that NMEA listeners are supposed to be isolated,
so it should be perfectly fine to attach an RS-232 talker to an NMEA
listener.

That is correct.

I'm just not sure everyone implemented that particular
feature, given the workmanship I've seen in the instruments I've
cracked open. So, for the record, when speaking for public
consumption, I prefer to play it safe.

And that is correct too. Many mfg's have just a single ended input aka 'in'
vs. 'gnd'. Even many with a + and - (differential) you cannot be sure if
they have isolation. Pity that the NMEA organisation does not 'approve'
designs. But rest asu my muxes all have optocouplers inside :-)

Meindert

"Glen Wiley Wilson" wrote in message
...

On a different subject, do you know what's going on with NMEA2000?
Did it wind up being CAN, and is anyone supporting it yet? It looks
like a sweet deal for the instrument makers. RS-232/CAN convertors
are 3 times the price of RS-422/RS-232 and it looks as if they could
potentially lock out anyone who doesn't pony up the fee to get an ID
assigned. But maybe I'm just paranoid...

Well, it's pretty expensive to get NMEA2000 running for the first product.
All standards, testsuites and manufacter- and product ID for the first
product sets you back for $10,500. So I'll stick to NMEA 0183 for a while
:-)

As far as I see it, only the big guys go for NMEA2000.

Meindert

There was a write up in this month's Ocean Navigator. Thus far only 5
products have been fully certified but another 40 are in the process.
Teleflex has a full line of CANbus engine controls. One thing for sure,
it will be more expensive. The prices for just the cable connectors is
outrageous and no doubt we will end up eating our share of the
certification costs. NMEA charges an arm and a leg for almost
everything they do like that.

Meindert Sprang wrote:

"Glen Wiley Wilson" wrote in message
...

On a different subject, do you know what's going on with NMEA2000?
Did it wind up being CAN, and is anyone supporting it yet? It looks
like a sweet deal for the instrument makers. RS-232/CAN convertors
are 3 times the price of RS-422/RS-232 and it looks as if they could
potentially lock out anyone who doesn't pony up the fee to get an ID
assigned. But maybe I'm just paranoid...


Well, it's pretty expensive to get NMEA2000 running for the first product.
All standards, testsuites and manufacter- and product ID for the first
product sets you back for $10,500. So I'll stick to NMEA 0183 for a while
:-)

As far as I see it, only the big guys go for NMEA2000.

Meindert



--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Did they change the spec? I got ahold of one of the later prelim specs
and just like 0183, they specified no connectors and were pretty solid
on the fact that the flexability of not specifying them was a good thing.

Doug

"Glenn Ashmore" wrote in message
news:TDylb.86906$sp2.60656@lakeread04...
There was a write up in this month's Ocean Navigator. Thus far only 5
products have been fully certified but another 40 are in the process.
Teleflex has a full line of CANbus engine controls. One thing for sure,
it will be more expensive. The prices for just the cable connectors is
outrageous and no doubt we will end up eating our share of the
certification costs. NMEA charges an arm and a leg for almost
everything they do like that.

Meindert Sprang wrote:

"Glen Wiley Wilson" wrote in
message
...

On a different subject, do you know what's going on with NMEA2000?
Did it wind up being CAN, and is anyone supporting it yet? It looks
like a sweet deal for the instrument makers. RS-232/CAN convertors
are 3 times the price of RS-422/RS-232 and it looks as if they could
potentially lock out anyone who doesn't pony up the fee to get an ID
assigned. But maybe I'm just paranoid...


Well, it's pretty expensive to get NMEA2000 running for the first
product.
All standards, testsuites and manufacter- and product ID for the first
product sets you back for $10,500. So I'll stick to NMEA 0183 for a
while
:-)

As far as I see it, only the big guys go for NMEA2000.

Meindert



--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com