NMEA Protocol Datatype

Vaitheeswaran

Member
Join Date
May 2019
Location
Madurai
Posts
20
Hello,
I am using Trimble 2000 GPS, I had been trying to take the Latitude and Longitude data in my controller and SCADA. I took position data from GLL package using Functional Block Diagram(Isagraf Software). But I need to show the data in SCADA(Wonderware Intouch). The GLL package data will be like "$GPGLL,3723.2475,N,12158.3416,W,161229.487,A,A*41" this. Here i need to take both 3723.2475,N and 12158.3416,W through modbus address in SCADA. I need to know what's the datatype of the values 3723.2475 and 12158.3416, is it ASCII or Decimal. When i tried to get these values in Wonderware Intouch it's showing a complete different value. If these data's are ASCII could you please tell me if Wonderware intouch can read/get ASCII values?


Thanks and Regards,
Vaithees :)
India.
 
Having worked with NMEA a lot I can tell you that you need to treat it as a string the number is actually 2 pieces of data which you will here sailors refer to as hours and minutes of longitude and hours of minutes as latitude. You can parse out as individual strings or make the whole thing a string. strings are stored in Modbus registers as bytes so there are two characters stored per register.
 
Hey Fred,
I had already did that, i took degree, minute, direction(North/South or East/West) as a separate string. Look at the attached image i had mentioned the each and every thing. In the N/S and E/W it should be shown as a string it shows as 306.00000000 for both and for the Latitude and Longitude the Degrees, Minutes and the whole data should be like 37°23.2475,N but its showing values like 818.00000000, 1586.00000000, 1074.00000000. Please help me with this.

Edit2.jpg
 
Last edited:
Unfortunately I am not a Wonderware Expert but if you are parsing the output into string variables then it should display as string variables unless the objects you are using to display the data in on the screen are converting them to a number/float.

Are those digital display objects or smart objects?
See of there is a property that can force them to display string/ascii data only.
 

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