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NMEA-0183

NMEA-0183

NMEA-0183 communication protocol

Supported device types and versions 
Communication line configuration
Communication station configuration
I/O tag configuration
Errors and problems
Geofencing - localization of the position
Literature
Changes and modifications
Document revision

Supported device types and versions

This protocol supports the communication with GPS receivers that send data according to NMEA-0183 standard. It supports only data receive.

Communication line configuration

File I/O communication line

The implementation of the NMEA-0183 protocol supports the reading of files that contain NMEA packets/records. As NMEA-0183 records are text strings with CR-LF in the end, one row of the file must contain a single NMEA-0183 record.

The files are searched in the directory according to the setting of the "Input file" parameter on the "File I/O" tab in the configuration of the line. The file must correspond to a mask according to the Filename Mask station protocol parameter. The file is analyzed (read) from top to bottom, after processing it is moved to the archive directory according to the setting of parameter "Archive directory" on the "File I/O" tab in the configuration of the line. In this directory, the subdirectories with the time of creation or data analysis are created (see the "Archive subdirectory time mask" parameter).

Protocol line parameters

Dialog window of Line configuration - tab "Protocol parameters", choose the protocol NMEA-0183.
They influence some optional parameters of the protocol. You may set the following parameters for the line:

Table 1

Full name

Meaning

Unit / Size

Default value

Archive Subdirectory Time Mask

A mask used to create the archive subdirectories for storing the processed files (important only for File I/O lines). Use the following text string to set mask::
"yy" or "rr" - year (short format),
"yyyy" or "rrrr" - year (long format),
"mm" - month,
"dd" - day.

-

yyyymm

Geofencing Polygons Definition File

Full path to a file that contains a definition of polygons (a localization of position in polygon - geofencing). Blank text disables the localization feature. See chapter Geofencing - localization of position.

-

-

Files Checking Period

The time period of reading of the source directory.

mi:ss

01:00

Unknown Files Backup Directory

Backup directory for storing unknown files.

-

-

After Processing Timeout

Delay after processing of a file.

ss.mss

00.100

Future Data Filter

Time filter of data. If the timestamp of received data deviates from the current time by more than defined hours in the future, they are ignored. Set 0 (zero) to ignore the time filter.

hours

0

History Data Filter

Time filter of data. If the timestamp of received data deviates from the current time by more than defined days in the past, they are ignored. Set 0 (zero) to ignore the time filter.

days

0

Additional Error Logfile

Additional error log file for tracing communication errors

-

-

Communication station configuration

  • Communication protocol "NMEA-0183".

  • As for Serial and SerialOverUDP Device Redundant lines (i.e. asynchronous serial communication), the address parameter is not required (blank text). The protocol NMEA-0183 does not support the addressing of devices. Data are sent spontaneously. Only one device may be connected to one serial asynchronous communication line.

  • As regards the File I/O line, the address may be any text string. It can be used for searching the file with NMEA data for the given station (see the Filename Mask station protocol parameter).

Station protocol parameters

Dialog window for configuration of station - tab "Protocol parameters".
They influence some optional parameters of the protocol. You can set the following parameters:

Table 2

Full name

Description

Unit / Size

Default value

Maximum Wait Retry

A retry count of reading response until its completion.
Maximum retries of reading of line so that the NMEA packet/record is complete (it is relevant only for Serial and SerialOverUDP Device Redundant lines).

-

40

Wait Timeout

Delay between the readings of the line until NMEA packet/record is complete (it is relevant only for Serial and SerialOverUDP Device Redundant lines).

ms

50 ms

Position Data Format

Conversion of data of geographical position from NMEA records GPRMC.3, GPRMI.1, GPGGA.2, GPGLL.1, PGRMF.6 for latitude and GPRMC.5, GPRMI.3, GPGGA.4, GPGLL.2, PGRMF.8 for longitude. You can choose "deg/min" (a native format of NMEA, the same value as it has been read) or "deg" (conversion to degrees).

deg/min
deg

deg

Speed Units

Conversion of data about the speed to a required technical unit (GPRMC.7 and GPVTG.3 in knots, GPVTG.4 and PGRMF.12 in km/hour).

knots
km/hour

knots

Trace Received Data

Show information about the received raw data.

YES/NO

YES

Trace Received Values

Show details about analyzed values of I/O tags.

YES/NO

YES

Filename Mask

Mask for searching of files with NMEA information (it is important only for File I/O). Mask must be a text string with support of special items in braces {}:
{N...N} - address of station, 'N' character count must be equal to the length of station address,
{yyyy} or {yy} - year (short/long format),
{mm} - month (1 to 12),
{dd} - day (1 to 31),
{hh} - hour (0 to 23),
{mi} - minute (0 to 59),
{ss} - second (0 to 59).
Digit placeholder '*' may be used also at any position in a mask.
Examples:
nmea_data.*
nmea_data*.txt
nmea_data{NNN}.txt
nmea_data{yyyy}{mm}{dd}_{hh}.txt
station_{NNNNNN}*

-

 

Synchronize Time Delta

Positive value activates the correction of system time from GPS data. If the difference between the system time and time received from GPS is greater than the value of this parameter (in milliseconds), a task that adjusts system time will be started. Time will be adjusted in small steps to avoid a sudden time-jump which is usually undesirable.
The default value of this parameter is 0 and it means that time synchronization is disabled.

ms

0

Long Difference Time

If the absolute value of a computed time difference between GPS time and system time is greater than the value of the parameter Long Difference Time, then the correction of system time will not be started immediately. Instead, the D2000 KOM process detects whether this difference is repeated at least Long Difference Count times consecutively. If it does and if the absolute value of the difference of consecutive time differences is not greater than Long Difference Time then the correction of system time will be started.
Parameters are meant as a protection of random occurrence of "out of range" time. Value 0 of parameter Long Difference Time disables this protection.

sec

0

Long Difference Count

-

0

Align To Minutes

KOM process publishes only the values received on the edge of a new minute (sec = 0). For proper functionality, the polling period must be less than one minute.

YES/NO

NO

External Command File

Full path to the external command file which is called with the defined period. Empty text string means that the external command file is not used.

-

 

External Command Period

The period for calling external command file. If the value is 0 seconds, the command file is called always before data reading from the particular station.

min:sec

60 sec

Call External Command Synchronously

Call external command file synchronously (YES) or asynchronously (NO).

YES/NO

YES