User manual

IEC61131 User and Reference Manual
April 22, 2008
246
dlogfcfg
Configure Data Log to File
Data Log to File Operation Overview
The SCADAPack 330 and SCADAPack 350 controllers and SCADASense 4203 support
data logging to the internal file system and the SCADAPack 330 and SCADAPack 350
controllers support data logging to a mass storage device connected via the USB host port.
Each data log can be independently configured to write data to either the internal file system
or a mass storage drive connected through the USB host interface.
Each data log creates a configurable number of data log files. Data Log records are buffered
to optimize file-writing dynamics. The log specific buffer is flushed to the active log file once
per minute.
Each log can be suspended and resumed. In a suspended state data log records can still be
written to the log, but the buffer won‟t be flushed to file. The state is useful when external
medium has to be exchanged.
Data Log Storage Medium
Data log files are stored either on the internal file system or an external drive in form of an
USB memory stick or an USB hard drive. If more than one USB drive is connected through a
hub, only the first drive connected is the active USB log drive.
Logging to File Mechanism
The data is buffered in RAM before being written to file. The buffer holds a maximum of 600
records. This is done to optimize data writes to file and reduce the total CPU load. The data
is buffered in non-volatile memory so that a power cycle does not result in the loss of data.
The structure for a single log file is shown below.
A single log file is made up of a configured number of records with each record containing a
maximum of 8 data fields. Records are added to the buffered data in RAM each time the log
data input for the DLGF function transitions from OFF to ON.
Once per minute the records that have been added to the buffered data in RAM are added to
the log file in the internal drive or the mass storage drive. Based on the number of records
configured and the logging interval eventually the log file will be full.
There are two methods for handling the full file:
 Logging can be configured to stop when the maximum number of records and
maximum number of log files has been reached. In this case there is a single log file
configured and logging will stop when all records are filled.
 Logging can be configured to overwrite the oldest log file, with a new file, when the
maximum number of log files is reached. In this case there is a single log file