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 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
Category of communication line: Serial, SerialOverUDP Device Redundant or File I/O.
Parameters of Serial line are set according to setting of GPS equipment.
File I/O communication line
The implementation of NMEA-0183 protocol supports the reading of files which contains NMEA packets/records. As NMEA-0183 records are text strings with CR-LF at the end, in one row of file must contain one NMEA-0183 record.
The files are searched in the directory according to the setting of parameter "Input file" on the tab "File I/O" in the configuration of line. The file must correspond to a mask according to the parameter "Filename Mask" in protocol of station. 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 tab "File I/O" in configuration of line. In this directory, the subdirectories with the time of creation or data analysis are created (see the parameter "Archive subdirectory time mask").
Protocol line parameters
Dialog window of
Line configuration - tab "Protocol parameters", choose the protocol NMEA-0183.
They influence some optional parameters of 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 which is used to create the archive subdirectories for storing of
the processed files (important only for File I/O lines). Use the following
text string to set mask:: | - | yyyymm |
Geofencing Polygons Definition File | Full path to a file which contain a definition of polygons (a localization of position in polygon - geofencing). Blank text switches of the localization feature. See the chapter Geofencing - localization of position. | - | - |
Files Checking Period | Time period of loading of source directory. | mi:ss | 01:00 |
Unknown Files Backup Directory | Backup directory for storing the unknown files. | - | - |
After Processing Timeout | Delay after processing of file. | ss.mss | 00.100 |
Future Data Filter | Time filter of data. If the time stamp 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 time stamp 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 File I/O line, the address may be any text string. It can be used for searching of the file with NMEA data for the given station (see the parameter "Filename Mask" on protocol of station).
Station protocol parameters
Dialog window for configuration
of station - tab "Protocol parameters".
They influence some optional parameters of protocol. You can set the following
parameters:
Table 2
Full name | Description | Unit / size | Default value |
|---|---|---|---|
Maximum Wait Retry | Retry count of reading response till its completion. | - | 40 |
Wait Timeout | Delay between the readings of 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" (initial form of NMEA, the same value as it has been read) or "deg" (conversion to degrees). | deg/min | deg |
Speed Units | Conversion of data about speed to required technical unit (GPRMC.7 and GPVTG.3 in knots, GPVTG.4 and PGRMF.12 in km/hour). | knots | knots |
Trace Received Data | Show information about 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 {}:
| - |
|
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 value of this parameter (in miliseconds), 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. | ms | 0 |
Long Difference Time | If absolute value of a computed time difference between GPS time and system time is greater than parameter Long Difference Time then
the correcton of system time will not be started immediately. Instead KOM detects whether this difference is repeated at least Long Difference Count
times consecutively.
If it does and if absolute value of difference of consecutive time differences is not greater than Long Difference Time then the correcton of system time will be started. | sec | 0 |
Long Difference Count | - | 0 | |
Align To Minutes | KOM process publishes only the values received on the edge of 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 |