In order to access the core monitoring data (i.e. the raw data of each monitoring cycle) that PRTG Traffic Grapher acquires from a device you can export the data into CSV files.

If  you enable the CSV export (in each sensor's settings) you will get a daily CSV logfile for each sensor with the results of each refresh cycle. The file is placed in the daily subfolders ("yyyymmdd") of your PRTG monitoring data folder named "{sensorid}.csv" (e.g. "{D7BB45A1-0550-4201-93AF-F6EADFEC2D05}.csv").

The file uses standard CSV format, can be loaded with e.g. Excel or Notepad and looks like this (note: the first line was wrapped):

"date","time","timecode (seconds since 2000/1/1)",  
    "kbits_per_sec_in","kbits_per_sec_out","bytes_in","bytes_out"
"2003-12-31","12:57:59","126190679",18,27,2014,2948
"2003-12-31","12:58:03","126190683",56,24,32843,11954
"2003-12-31","12:58:08","126190688",7,4,4325,2759
"2003-12-31","12:58:13","126190693",74,204,51161,140067
"2003-12-31","12:58:18","126190698",133,20,74608,11260
"2003-12-31","12:58:23","126190703",55,116,34203,72308
"2003-12-31","12:58:28","126190708",181,56,113430,34827
"2003-12-31","12:58:33","126190713",17,7,10415,4134

As usual for CSV files the first line contains a short description of the columns. The columns are:

• 1st: Date (string)
• 2nd: Time (string)
• 3rd: Timecode (integer, the number of seconds since January 1st 2000 00h00m00s)
• 4th to n-th: Value(s)

For traffic sensors:

• the 4th (incoming) and 5th (outgoing) columns contain the kbit/second values
• the 6th and 7th columns contain the number of bytes.
  
• To get the number of bytes transferred over a certain time you must sum up the values in columns 6 and 7.
  
• To create a graph of bandwidth (bit/s) you must create a graph using date/time and columns 4 and 5.

For other sensors:

• there is one column per channel with the channel name in the heading. The unit is the base unit of that sensor (for packet sniffer and netflow sensors this is bytes).
• If it is a delta (difference per period) sensor you get these columns twice. The first with speed (per second) and the second  for the volume (similar to the traffic sensors).

When the "Extended CSV Format" option is enabled there are several additional columns:

• ID: The unique ID internally used to identify the sensor (the filename uses the same id)
• Name: Name of the sensor
• Group: Position of the sensor in the sensor tree
• Host: IP or dns name of the host
• Hostalias: The alias name of the host
  

Note: This information applies to PRTG Traffic Grapher 5.3 or later