Replaying RS232 Data

In digitized mode, the data level is sampled and stored in synchronisation with the recorded GNSS data. When replayed, the levels are recreated and output via a voltage level shifter to the RS232 output of the LabSat 4 unit. The benefit of this method is that you are not required to configure the baud rate. You can also use this method to capture binary data that does not use the ASCII format.

Log File mode is suitable for recorded ASCII text-based message data. As data is received, a new time stamped line is created in a log file which is has the same name as the GNSS signal data but with a .ser extension. Each byte of incoming data is added to the line until the LabSat 4 unit recognises a carriage return [CR] or a line feed [LF] character. On receiving a CR, LF or both characters together, a new line is started in the text file with a new timestamp for the next received character.
 

An example of an ASCII formatted message would be NMEA data from a GNSS module:
 

$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47

Because Log File data is received and processed by the LabSat 4 unit, you must configure the correct data or baud rate on the LabSat 4 unit. The standard rate for NMEA is 4800 bit/s but it is not uncommon for systems to use other rates such as 9600 or 115,200 bit/s per second.
 

Example of a log file
 

The first section of the log file contains details such as the serial number of the LabSat 4 unit, the date and time of recording and the baud rate settings. After the [TIME] and character heading, the received data will appear along with the timestamp of the start of each line.

When you replay a recording with logged RS232 data, the LabSat 4 unit uses the timestamp in the file to replay each line at the corresponding time.

Once a Log File has been created, you can modify the log file by using a text editor application such as Notepad, to change the replayed output.