RS232 vs RS422 (AIS/plotter integration)

demonboy

demonboy

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My AIS Comar CSB200 has an RS232 that used to go to my laptop. My new B&G plotter says it uses RS422 and we have been supplied with a cable with four stripped ends ready for connection.

Is there a way of taking the RS232 output from my AIS and splitting it to both USB and to the B&G cable? If not, can I take the RS232 output and wire it directly to the B&G cable, even though it is RS422?

Edit: Just seen this on Amazon and wondered if this would be a solution: http://www.amazon.co.uk/StarTech-co...1-fkmr1&keywords=rs232+split+to+rs422+and+usb
 
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demonboy said:
My AIS Comar CSB200 has an RS232 that used to go to my laptop. My new B&G plotter says it uses RS422 and we have been supplied with a cable with four stripped ends ready for connection.

Is there a way of taking the RS232 output from my AIS and splitting it to both USB and to the B&G cable? If not, can I take the RS232 output and wire it directly to the B&G cable, even though it is RS422?
Click to expand...

As the input on the B&G plotter is NMEA-0183 you can feed it a signal with RS232 or RS422 voltage levels. Tiz in the standard that a device must accept either.

Not sure what you are doing with the USB. You will have to explain further.
 
AngusMcDoon said:
As the input on the B&G plotter is NMEA-0183 you can feed it a signal with RS232 or RS422 voltage levels. Tiz in the standard that a device must accept either.

Not sure what you are doing with the USB. You will have to explain further.
Click to expand...

Hi Angus - the USB is to send the signal to my netbook, which I use as backup. I was confused as to why B&G states it is RS422. What is the difference in this instance? Surely they are both DB9 and use the same cables, or is that not the case?
 
My setup is NASA AIS (RS232 out) feeding my SH DX2000 radio and my onboard PC which only has USB. I made up a cable using male and female 9 pin Dtype connectors back to back with the RS232 output/ground cable to go to the radio AIS input from between the D-types then I plugged a RS232 converter into the now spare D-type connector then to the USB on the PC/Laptop.

The radio also needs GPS input which is also RS232. I have a spare RS232 GPS mouse and an doing the same to feed the GPS to the Radio and to my newly received crew watch sent by Angus ( Thks Angus it works great will post about my setup next time I am on the boat and installed properly.
 
Is this a simple RS232 output from the AIS or is it NMEA0183?

If it's a basic RS232 serial port you can't normally wire RS232 and RS422 together directly you need a converter - some examples shown here (in the US):

http://www.serialcomm.com/serial_rs232_converters/rs232_to_rs422_converters.aspx

Similarly you'd need a USB to RS232 or RS422 convertor, this is quite simple and they aren't expensive, RS232 is more common such as here (same site in the US):

http://www.serialcomm.com/USB_adapters/USB_converters/usb_to_rs485_rs422_adapter/usb_to_rs485_rs422_adapter.product_general_info.aspx

RS232 and RS422 are point-to-point so you can't split a single RS232 to USB/RS422 in a simple way as there's no point-to-multi-point support defined.

However if it's an NMEA0183 output from the AIS (which uses RS232 electrically but can support multi-point comms) then you'd be better off looking at an NMEA multiplexor that can take the AIS and pass it on down the chain to the plotter. You can get NMEA0183 to USB convertors too so you could just plug you laptop into the NMEA network via one of those.

Here's one from Brookhouse in New Zealand which takes 4 NMEA/RS232 inputs (including one version with an AIS-specific input) and outputs both RS232 and RS422, so does potentially everything you'd want (there's an optional add-on which gives a USB output as well):

http://brookhouseonline.com/nmea_multiplexer.htm

Note that one of their models has a wifi output so you could ditch the USB and just use that to connect to your laptop if you wanted.

I haven't used one of these so you'd have to satisfy yourself about it, maybe someone with direct experience can chime in. There are other multiplexers from the big marine elec manufacturers, Raymarine's is about £150:

http://www.mesltd.co.uk/raymarine-nmea-0183-multiplexer-p-337.html

Hope that helps...?

Cheers

Neil
 
As Angus has said in the NMEA spec you can connect RS232 and RS422 into each other. This is how my SIMRAD instruments connect to my PC SIMRAD 422 into RS232 to USb converter.

In this case you dont need a multiplexer as you are feeding one RS232 output (the AIS) into 2 inputs in the OP case RS232 to USB and the B&G plotter.

In my case RS232 to USB and to the RS232 input of my SH AIS radio. The same with the GPS input to the radio and the input to Angus crew watcher.

Like this

https://www.google.co.za/search?q=rs232+splitter+cable&newwindow=1&tbm=isch&imgil=UgCQ58afIOwllM%253A%253BDcbKCLHbovbV4M%253Bhttp%25253A%25252F%25252Fwww.ethernut.de%25252Fen%25252Fdocuments%25252Frs232primer.html&source=iu&pf=m&fir=UgCQ58afIOwllM%253A%252CDcbKCLHbovbV4M%252C_&usg=__gYX4bSFrhF8JKeBeVvd9Km0IFDc%3D&biw=1280&bih=655&ved=0CDYQyjc&ei=UJiaVK2XNoqxUd_hgaAL#facrc=_&imgdii=_&imgrc=6eFF3ZlXHScpTM%253A%3BuKcd6EVOGAb5BM%3Bhttp%253A%252F%252Flefebure.com%252Farticles%252Frs232-splitter-cable%252Frs-232-splitter-cable.png%3Bhttp%253A%252F%252Flefebure.com%252Farticles%252Frs232-splitter-cable%252F%3B679%3B328
 
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Nigel

OP wants to feed RS232 from a AIS in both PC and a B&G plotter, so 1 RS232 output into 2 RS232 inputs.

This is also my requirement x 2.

Your info will feed 2 RS232 outputs into one USB PC input.

You could do it you way but the PC would need to feed data back to one of the devices IMHO over complicated.
 
Rogershaw said:
Nigel

OP wants to feed RS232 from a AIS in both PC and a B&G plotter, so 1 RS232 output into 2 RS232 inputs.

This is also my requirement x 2.

Your info will feed 2 RS232 outputs into one USB PC input.

You could do it you way but the PC would need to feed data back to one of the devices IMHO over complicated.
Click to expand...

So just connect the two inputs together and to the AIS's output. You can drive several inputs from one output. RS232 signals 'officially' range from -12 to + 12, but the actual switching points are about +0.8v and + 1.6v hence are compatible with all NMEA equipment. The inputs are usually photo couplers anyway so provided 2ma is available from the source per input, the actual voltage isn't critical.
 
ianj99 said:
So just connect the two inputs together and to the AIS's output. You can drive several inputs from one output. RS232 signals 'officially' range from -12 to + 12, but the actual switching points are about +0.8v and + 1.6v hence are compatible with all NMEA equipment. The inputs are usually photo couplers anyway so provided 2ma is available from the source per input, the actual voltage isn't critical.
Click to expand...

My info is that RS232 switching points between +12 & +3 and -12 & -3, that's how built my RS232 light box some 35 years ago. I dont think RA232 specified photo coulpers but 422/3 does and in effect is a current drive not voltage but it seems to work.

Any way NMEA specify one output can drive upto 3 or 4 inputs and on my SIMRAD system I have IS11 instruments driving at lease 4 inputs including RS232 to USB and SIMRAD plotter and autopilot.
 
Rogershaw said:
My info is that RS232 switching points between +12 & +3 and -12 & -3, that's how built my RS232 light box some 35 years ago. I dont think RA232 specified photo coulpers but 422/3 does and in effect is a current drive not voltage but it seems to work.

Any way NMEA specify one output can drive upto 3 or 4 inputs and on my SIMRAD system I have IS11 instruments driving at lease 4 inputs including RS232 to USB and SIMRAD plotter and autopilot.
Click to expand...

Yes you are right on the voltage 'range' but the point is that it encompasses the operating levels of a NMEA input.
 
That's because the 422 is a low impedance input and the RS232 id a higher output impedance thus dropping the output voltage but it still works anyway so what the hell. The only issue is then the number of inputs you can connect before the voltage of output becomes lower than the detect level of the input devices. That why on some installations some of the input devices will see the signal and some won't and that can cause some head scratching.
 
demonboy said:
Hi Angus - the USB is to send the signal to my netbook, which I use as backup. I was confused as to why B&G states it is RS422. What is the difference in this instance? Surely they are both DB9 and use the same cables, or is that not the case?
Click to expand...

There's some mis-information on this thread, so I have written a brief explanation of NMEA-0183 voltage levels here...

http://yappelectronics.co.uk/nmea.htm

All comments will be received and acted upon some time. :)
 
Thanks for the info, ppl. Hope you had a nice break. The output on the Comar, btw, is a 9-way D-type female connector. Whether that makes it RS232 or NMEA0183, I'm afraid I don't know the difference.

I had a conversation on Christmas Eve about this subject and came up with a possible alternative, which I'd appreciate your feedback on. The output from the AIS could go straight to the B&G plotter (so that's from the D-type 0183 on the AIS to RS422 on the plotter), which is part of an ethernet network with wifi. Could I not then just log into the B&G network on my laptop and pick up the NMEA data (somehow) from that, to be seen on OpenCPN?
 
OpenCPN will looks for a RS232 port. This can be real or virtual like RS232 to USB.

Have not done it with wifi but looks like this or similar may be needed.

https://serialio.com/products/mobile/wifi/software/WiSnapCOMTCP.php

I used a home made version of one of these with no problem and no third party software to setup

http://www.yourcablestore.com/1-Foot-9-Pin-Serial-Splitter-Cable-DB9-1M-2F-RS232_p_242.html

There will be lots of suppliers of similar products around as most will be made in China.

http://electronics.stackexchange.co...plit-one-rs232-output-signal-into-two-signals

This is a question like yours on an electronics info exchange.

Hope it helps

Generally 9 pin D type are RS232 and I found most NMEA are just bare wires or screw terminals but different manufactures can do different things so no guarantee.
 
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demonboy said:
My AIS Comar CSB200 has an RS232 that used to go to my laptop. My new B&G plotter says it uses RS422 and we have been supplied with a cable with four stripped ends ready for connection.

Is there a way of taking the RS232 output from my AIS and splitting it to both USB and to the B&G cable? If not, can I take the RS232 output and wire it directly to the B&G cable, even though it is RS422?

Edit: Just seen this on Amazon and wondered if this would be a solution: http://www.amazon.co.uk/StarTech-co...1-fkmr1&keywords=rs232+split+to+rs422+and+usb
Click to expand...
I connected my RO4800 AIS radio output to my VYacht Wifi transmitter set at RS232. It woukdnt transmit anything, I fiddled and set the RO4800 to RS422 and bingo it all worked! Quite why I dont know, it was supposed to work with RS232.
S
 
drakes drum said:
If your new B&G plotter is like mjy new B&G plotter, then under the system settings menu - the network bit - it gives you a choice of either input.It isnt just 422
Click to expand...

It runs on NMEA2000, being ethernet-based, but the video-in allows for NMEA0183 as well. It looks like OpenCPN allows for TCP networking so I can pick up the NMEA via wifi, provided the laptop is connected to B&G's network. This still doesn't get round the initial problem of outputting to the laptop from AIS separately because I'm now dependent upon the wifi network (my laptop is a backup in case the B&G packs up), but I picked up a DB9 connector and should be able to wire it for both laptop (RS232) and B&G (RS422). Problem solved, in a round-about way.
 
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