Syntax.: _NMEAChecksum($sData ) Parameters. : Takes a NMEA sentence, and returns its validity, or calculates its checksum. I have tested the code on the following NMEA sentences and it works perfectly

The checksum is calculated and added to each sentence and is used to confirm that the data contained within each sentence has not been corrupted. WTF is a NMEA sentence? Well the short answer is its the standard protocol used by a GPS receiver to create a sentence from data streamed from a GPS Satellite. I would like to confirm that your help is very much appreciated. I will check it further to make sure that it works on all NMEA sentence types. Not knowing WTF an 'NMEA checksum' is, I obviously can't be sure, so over to you. Global $input = 'GPGLL,5300.97914,N,00259.98174,E,125926,A' Global $result = NMEA _Checksum ( $input ) MsgBox ( 0, 'NMEA Checksummmer', ' input: ' & $input & & 'output: ' & $result ) Func NMEA _Checksum ( $string ) Local $ret = 0 For $i = 1 To StringLen ( $string ) $ret = BitXOR ( $ret, Asc ( StringMid ( $string, $i, 1 ) ) ) Next Return Hex ( $ret, 2 ) EndFunc This worked for me (as in: gives the answer you specified) strChecksum=checksum.ToString(“X2”).Ĭan this calculator be coded in AutoIT and is their an example available? In VB.Net and C# you can use the ToString function for this, e.g. What is left is to transform the checksum into two hexadecimal characters, and that is it. Int checksum = 0 for (inti = 0 i checksum ^= Convert.ToByte(sentence ) }ĭim checksum as Integer = 0 For Each Character As Char In stringToCalculateTheChecksumOver checksum = checksum Xor Convert.ToByte(Character) Next Var checksum = 0 for(var i = 0 i checksum = checksum ^ stringToCalculateTheChecksumOver.charCodeAt(i) } Then just XOR the first character with the next character, until the end of the string.īelow you find a code example in Java script, VB.Net and C#. In the examples below the name of this new string is stringToCalculateTheChecksumOver. To calculate the checksum you parse all characters between $ and * from the NMEA sentence into a new string. The string that the checksum is calculated over is In this sentence the checksum is the character representation of the hexadecimal value 28. To release the point, click anywhere on the map.Calculating the checksum is the representation of two hexadecimal characters of an XOR of all characters in the sentence between – but not including – the $ and the * character. Pressing the 'Enter' key will move the point to the new specified location. First, select a point, then you will be able to change its latitude and longitude values on the menu (left side). The 'Edit point' tool allows you to directly set the latitude and longitude values for a point. Setting latitude and longitude values for a point Clicking once again will release the point at its current position. To move a point, click on it first to select it: the point will then start following the mouse cursor. The 'Move point' tool can be used to manually move points around. the GPS frequency) will however not be preserved. The map view will be preserved, so you will not lose the location you are currently working on. To delete all points, simply reload the application. To delete a point, select the 'Delete point' tool and click on the point you wish to delete. The time elapsed between two consecutive points is always the same and equal to one second by default, but this can be changed under 'Global settings'. When you click on the map using this tool, a point is added to your path at the location you clicked on.Ī point represents a position measured using a GPS device being carried around. The 'Add point' tool is selected by default when the NMEA Generator is started.

Nmea checksum calculator