To make matters even worse, a lot of devices you THINK are USB devices have the
converter chip inside them somewhere and have the same issues, with the
drawback that you can’t change it.
See any number of cheap interface cables for OBD car diagnostics. I think I
have 2 or 3 that won’t reliably connect.
Also note NMEA 0183 and RS-232 are not the same voltage specifications. Well
over 90% of the time they play well together, but not 100%. I had a non-marine
GPS puck that had an RS-232 serial connection. It worked OK for just the
laptop, but failed driving the laptop, the VHF, and the APRS tracker. I had to
buy a marine Garmin unit that had a true buffered NMEA output with enough power
to deal with multiple listeners.
From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Marek
Dziedzic via CnC-List
Sent: Thursday, September 15, 2016 10:39 PM
Cc: Marek Dziedzic
Subject: Re: Stus-List USB to Serial - reading NMEA stream
I cannot answer any of the really technical questions, but…
There is, generally, a problem with eth USB2Serial adapters. One of the most
common is that the adapter does not have the real Prolific h/w; rather is an
imitation. This happens even if you purchased the adapter from a reputable
source. This is a reasonably well know issue. To the point that some s/w
developers refuse to support a solution if a USB2Serial adapter is used. I had
major stability problem with my previous weather station that used a serial
connection and a special rain dance or waving a chicken leg was often required
in order to make it connect.
So, in short, there may not be a bullet proof USB2Serial driver.
From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Dennis C.
Sent: Thursday, September 15, 2016 17:26
To: CnClist <CnC-List@cnc-list.com<mailto:CnC-List@cnc-list.com>>
Cc: Dennis C. <capt...@gmail.com<mailto:capt...@gmail.com>>
Subject: Stus-List USB to Serial - reading NMEA stream
Really technical question here.
I'm try to solve a puzzling issue on Touche'. I installed a Noland AM43
multiplexer to gather wind data from my Nexus instruments and send it to my
Simrad WP30 wheel pilot. That works now. However, in the process, the WP30 is
not receiving the waypoint arrival alarm. When the WP30 was interfaced
directly to the GPS, it always deactivated "Nav" mode when we got to 0.10 nm of
a waypoint and the arrival alarm activated. Now I hear the GPS audible alarm
but the WP30 keeps on steering.
I know the WP30 is receiving GPS data because it steers right past the waypoint
and gradually changes course and navigates dutifully to the next waypoint in
the route. The Nexus instruments show all the correct data, distance/bearing
to waypoint, course to steer, cross track error, etc.
I have what I consider the appropriate sentences programmed into the Nexus NMEA
output slots; APA, APB, RMB, etc.
I want to read and log the data stream. The AM43 has a USB port.
I have a Dell mini laptop with a Prolific PL2303 USB to Serial driver
installed. It usually shows on COM3. I have two applications, GPSinfo and
DPort Lite (a lite version of Hyperterminal). I can see the NMEA data stream
from my Globalsat BU-353 GPS adapter on both applications but I have to unplug
and re-plug the BU-353 in some mystical order for it to be seen in DPort Lite.
Since there is no Wi-Fi or internet at my marina for troubleshooting, I want
some reasonable assurance that when I connect to the multiplexer, I will see
data. I two questions for the cyber-minded folks.
1. Is there a bombproof USB serial driver that will work every time with DPort
Lite without having to plug/unplug/reboot or place a chicken wing under a
cypress tree at full moon?
2. Where in the APA, APB, RMB sentences is the arrival alarm data and what
characters signal on or off?
Touche' 35-1 #83
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