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NMEA / USB wiring - help welcome ! - Printable Version

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NMEA / USB wiring - help welcome ! - Didier B - 02-06-2018

Hi,
How should I connect the NMEA output of my ST50 tridata repeater to the USB 422/485 adapter ? (see attachments)

[attachment=235][attachment=236]


On the ST50 instrument side are  2 wires 1 "signal" (red) and one "Ground" (blue) ;
On the adapter 5 screw connectors : R-, R+, T-, T+ and GND ;

I checked a signal is present on the ST50 equipment side (analogue multimeter, range 10VDC, the needle moves) ;
I tried, but without success these connections :
  • blue to GND, red to R+
  • blue to R-  red to R+
  • blue to T-, red to T+
  • blue to GND, red to T+
I'm stuck, has somebody already connected one of these NMEA/USB adapters ???


RE: NMEA / USB wiring - help welcome ! - marko_st - 02-07-2018

Hi, 
I'm not expert for this but as can see:

- on transmiter side is ST50 which have TTL(UART) output
- on receiver  side is USB port

That mean you need  UART to USB converter between this two parts.

You have USB to 485 converter, which is different protocol. 

Solution is use UART/USB adapter which is very cheap and just connect red from ST50 to RX, and blue to GND.
Then set baud rate and other and that is must work.

Maybe(just maybe, and I'm not responsible) you can tray connect red(ST50) to T+, blue(ST30) to T- (like you describe in 3nd option of wiring) and T- also to GND of ST30. 
Or 2nd option with R- also to GND of ST30.

Marko


RE: NMEA / USB wiring - help welcome ! - shipahoy - 02-07-2018

The ST50 is probably so old that it uses NMEA 0183 version 1. This is not RS422 but RS232.
You should try with a USB-RS232 converter (preferebly isolated). Remember to set the baudrate to 4800 baud.

(02-07-2018, 04:16 AM)marko_st Wrote: - on transmiter side is ST50 which have TTL(UART) output
That mean you need  UART to USB converter between this two parts.

I am quite sure that this would destroy the UART to USB converter because it only handles 0 to 3.3 or 5 V, and this output is probably ±12 V.


RE: NMEA / USB wiring - help welcome ! - marko_st - 02-07-2018

(02-07-2018, 04:18 AM)shipahoy Wrote: The ST50 is probably so old that it uses NMEA 0183 version 1. This is not RS422 but RS232.
You should try with a USB-RS232 converter (preferebly isolated). Remember to set the baudrate to 4800 baud.

(02-07-2018, 04:16 AM)marko_st Wrote: - on transmiter side is ST50 which have TTL(UART) output
That mean you need  UART to USB converter between this two parts.

I am quite sure that this would destroy the UART to USB converter because it only handles 0 to 3.3 or 5 V, and this output is probably ±12 V.
Maybe, but it will only be 12v not +/-12v.

This converter is very cheap so...
Maybe try to measure ST30 output with oscilloscope to check voltage. If it is 12v, you can use simple voltage divider with two resistor.

Poslano sa mog Redmi Note 4 koristeći Tapatalk


RE: NMEA / USB wiring - help welcome ! - shipahoy - 02-07-2018

Here is a lot of useful information: http://www.actisense.com/wp-content/uploads/2017/07/NMEA-0183-Information-sheet-issue-4-1-1.pdf


RE: NMEA / USB wiring - help welcome ! - Didier B - 02-07-2018

(02-07-2018, 07:57 AM)shipahoy Wrote: Here is a lot of useful information: http://www.actisense.com/wp-content/uploads/2017/07/NMEA-0183-Information-sheet-issue-4-1-1.pdf

Thanks a lot, very precious for an NMEA newbie !

(02-07-2018, 04:28 AM)marko_st Wrote:
(02-07-2018, 04:18 AM)shipahoy Wrote: The ST50 is probably so old that it uses NMEA 0183 version 1. This is not RS422 but RS232.
You should try with a USB-RS232 converter (preferebly isolated). Remember to set the baudrate to 4800 baud.

(02-07-2018, 04:16 AM)marko_st Wrote: - on transmiter side is ST50 which have TTL(UART) output
That mean you need  UART to USB converter between this two parts.

I am quite sure that this would destroy the UART to USB converter because it only handles 0 to 3.3 or 5 V, and this output is probably ±12 V.
Maybe, but it will only be 12v not +/-12v.

This converter is very cheap so...
Maybe try to measure ST30 output with oscilloscope to check voltage. If it is 12v, you can use simple voltage divider with two resistor.

Poslano sa mog Redmi Note 4 koristeći Tapatalk
Thanks for yor suggestion of a divider. I guess 12 to 5V ... Any suggestion for the impedance (from ST50 12 V side)  ?