QLG1 - Simple connection to PC USB Serial port


Chris Baragwanath
 

Hi

 

Can anyone please provide a novice with guidelines, hints or tips to connect a QLG1 RS232 serial port to a Win 10 PC via a USB serial port – the serial port connector is DB female type. This is just to see and better understand the NMEA sentences the QLG1 sends. Software on the PC is: ‘VisualGPS’ freeware.

 

Using HyperTerminal the port is definitely receiving something from the QLG1.

 

 

Many thanks in advance and kind regards,

 

 




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Alan G4ZFQ
 

Can anyone please provide a novice with guidelines, hints or tips to connect a QLG1 RS232 serial port to a Win 10 PC via a USB serial port - the serial port connector is DB female type. This is just to see and better understand the NMEA sentences the QLG1 sends. Software on the PC is: 'VisualGPS' freeware.
Chris,
Using HyperTerminal the port is definitely receiving something from the QLG1.
How are you connecting to see this? The above USB device?
Presumably if HyperTerminal sees something then GPS software should.
Pin 5 ground, pin 2 RXD from GPS TXD
There is other free software, u-center shows rather more than VisualGPS.

73 Alan G4ZFQ


KEN G4APB
 

On Mon, Apr 22, 2019 at 12:48 PM, Alan G4ZFQ wrote:
 
Alan,
to connect a QLG1 RS232 serial port to.... The QLG1 output is not RS232, it is 5v and TTL and will at least need to be inverted to feed it to a PC.

73 Ken G4APB


Alan G4ZFQ
 

to connect a QLG1 RS232 serial port to.... The QLG1 output is *not* RS232,
it is 5v and TTL and will at least need to be inverted to feed it to a PC.
Ken,

Thanks Ken:-)
It does get more difficult to be certain about polarity when USB adaptors are concerned.
A USB UART takes TTL from most modern GPS modules. A RS232 adaptor probably does not.

Chris,
If you see absolute gibberish with HyperTerminal then Ken will be correct, the Data line will have to be inverted. You should see NMEA messages which are almost gibberish but look as if they are telling you something.
Far better and easier is to get a UART. I've got all mine from Ebay for example https://www.ebay.co.uk/itm/CP2102-USB2-0-to-TTL-UART-Module-6Pin-Serial-Converter-Replace-FT232-Module-New/123527017817?epid=19026220568&hash=item1cc2c8b559:g:DBAAAOSwjoFcB3PX for a little more you will probably find a UK stockist.

73 Alan G4ZFQ


Graham, VE3GTC
 

The modules that Alan link to are very handy and I have several.

However, my favourite are these:

3.3V power and signal level  (3.3v is compatible with 5V ttl logic)

https://www.ebay.ca/itm/USB-to-TTL-Serial-Cable-FTDI-Genuine-chipset-3-3V-Transparent-with-LEDs/302695823027

or this for 5V power and signal level:

https://www.ebay.ca/itm/USB-to-TTL-Serial-Cable-FTDI-Genuine-chipset-5V-Transparent-with-LEDs/292901772167

Both have clear housing with LED so you can see that there is something on the TX and RX lines. They have genuine FTDI chips.

One of the reasons I like the FTDI chips is that there is a FTDI utility that lets you twiddled the devices settings including inverting the logic of each line:

https://www.ftdichip.com/Support/Utilities.htm#FT_PROG ( there are also many other utilities to be found there )

Yes, more $ but I find these cables much more useful.

There are many similar cables for less $ from your usual Asian sources but there is no guarentee that they will have a genuine FTDI chip but then again, there are other good alternatives.

The colour coding of the wires seems to be universal and I have yet to find a gps module that has it's TXD inverted with respect to the TTL serial data line. I seem to recall that the notion of inverted serial data was because the RS-232 converters put out a -V for a TTL + signal.

cheers, Graham ve3gtc

On 4/22/2019 15:20, Alan G4ZFQ wrote:

to connect a QLG1 RS232 serial port to.... The QLG1 output is *not* RS232,
it is 5v and TTL and will at least need to be inverted to feed it to a PC.
 Ken,

Thanks Ken:-)
It does get more difficult to be certain about polarity when USB adaptors are concerned.
A USB UART takes TTL from most modern GPS modules. A RS232 adaptor probably does not.

Chris,
If you see absolute gibberish with HyperTerminal then Ken will be correct, the Data line will have to be inverted. You should see NMEA messages which are almost gibberish but look as if they are telling you something.
Far better and easier is to get a UART. I've got all mine from Ebay for example https://www.ebay.co.uk/itm/CP2102-USB2-0-to-TTL-UART-Module-6Pin-Serial-Converter-Replace-FT232-Module-New/123527017817?epid=19026220568&hash=item1cc2c8b559:g:DBAAAOSwjoFcB3PX for a little more you will probably find a UK stockist.

73 Alan G4ZFQ


Alan G4ZFQ
 

They have genuine FTDI chips.
One of the reasons I like the FTDI chips is that there is a FTDI utility that lets you twiddled the devices settings including inverting the logic of each line:
Graham

Thanks, I had not come across that utility although after looking through the PDF I'm not sure I could pluck up the courage to use it:-)
Yes, I do have several FTDI adaptors, one 4 port used on my main SDR PC. I made sure they were FTDI as I got them during the fake Prolific era.
But I also do not know of a GPS module that works directly into a RS232 input. (And, of course, none of them should be connected to a RS232 output.)

I tried sending data from a GPS module into an adaptor yesterday. The GPS utility (Sirf configuration) showed error messages indicating it was seeing something on the COM port. Maybe that's what Chris saw in HyperTerminal.

73 Alan G4ZFQ