The data logger will log at the rate given in HH:MM:SS (hours, minutes, seconds). Logging is disabled if the rate is zero. If the "log only when" register number is zero, logging will be enabled continuously if the enable box is checked and rate is nonzero. If the "log only when" register contains a valid local register number, that register must be greater than zero before logging will be enabled (in addition to checking the enable box). This allows data logging to be tied to a schedule.

Eventually a log file will be come full, and you must decide what to do about that. In addition, available memory resources may be used up by other data loggers. Therefore, it is a good idea to manage all of the data loggers in a coordinated manner, allocating only an attainable size limit to each one.

You have the option of closing one file and starting a new one daily, weekly, or upon file full (size is met). At this point, you can allow the file to sit there until retrieved via FTP, or you can have the data log file automatically emailed as an attachment. If the "discard oldest" option is enabled, you can have a perpetual data logger requiring no particular log-in maintenance (as with FTP). To enable the email feature, enter a recepient email name (myname@myplace.com), a subject line for the email, and an optional message.

The "discard oldest" will discard the oldest file having the given file name as its name prefix. The oldest file will be deleted when there is no longer empty space available for the file size indicated for this log file. This rule applies independently for each log file rule set. Therefore, the event logger will never delete data files for data log #1, etc. The event logger will only delete oldest event log files.

You may find it desirable to delete old log files before you run out of room. To enable this automatically, enter a non-zero number of days for file life. The file will automatically be deleted after this number of days, but only if a new file is created in its place first. If you allow daily files to accumulate until you run out of room, the file list will become very long, and consequently response time for any functions requiring file name lookup becomes slow.

The file name you give above is only the first part of the name that is generated. The file creation date in the format YYYYMMDD is appended to this name. Therefore multiple files with the same "name" given above will still be unique file names. If you change the name after some amount of data has been logged with the old name, you must manually delete the old files. The "discard oldest" rule will only find files by the same name prefix currently defined above.

Log files will be sent at most once daily (unless file size is small and the file fills up). If the end time is later than current time when logging is first enabled, the file will not be sent at that time today; it will be sent at that time tomorrow. Logging daily does not mean you get precisely 24 hours of data. Daily means it will send a log file at most once a day, and never the same day the file was created.

You can log data to either RAM or FLASH memory. Data logged to RAM will be lost if power to this system is lost. The RAM area is known as directory RAM0 and has a capacity of about 200KB. The FLASH area is known as directory FLASH0 and has a capacity of 1.9MB. This FLASH0 area is shared with configuration files and program files. Note that Flash memory has a finite life. If you are logging data to Flash at a frequent rate, you may shorten the life of the product.

The specific rules followed for resource management are as follows:

If a file is full, i.e., its size setting is met, then disregard the schedule, send it now and request a new file. Until the file becomes full, check the schedule. If it should be sent now due to daily schedule settings, send it and request a new file. The "send it" applies only if email is configured (recipient given and server set up), but the new file request will always apply.

When a new file is requested, check the "discard" or "stop" setting. If "discard oldest" is selected, add up all log file sizes. If this much free space is not available, delete the oldest file with a name prefix matching the log configuration requesting a new file. If there are only zero or one older files, revert to "stop logging" rules. If "stop logging" is selected (by configuration or by default), check to see if there is room for 50% of just this file. If so, create it, otherwise disable this log.