Rosemount 3491 - Logging (3493 Only)

Reference Manual
00809-0100-4841, Rev. AA
May 2007
Rosemount 3490 Series
4-34
Logging (3493 Only) Menu: MAIN MENU / SETUP / [CONTROL UNIT /] LOGGING
Overview
Model 3493 will log up to 7000 events at regular intervals. An event is the
value of a parameter. The parameter to be logged is the one selected for the
middle section of the Primary Display (see “Primary Display Options“ on
page 4-72). This parameter is typically the MCU Primary Variable (MCU PV).
If model 3493 has been set-up to totalise the parameter value, the daily value
of the totaliser at midnight is also logged. Up to 60 midnight totalised values
will be held in memory. (This is in addition to the memory for 7000 events.)
In addition, the maximum instantaneous value of the parameter recorded in
each 24-hour period is logged.
Logged data may be downloaded at any time using the RS232 data port
socket provided for connection details (see “RS232 Connections“ on
page 3-13). You can download data using a PC with optional logger software.
NOTE:
See “Serial Communications“ on page 4-74 for associated parameters.
Model 3493 gives a visual indication that logging of data is underway by
flashing "LOG" in the bottom, right-hand corner of the Primary Display.
P590: Logging Interval
The logging interval is the period over which the parameter-to-be-logged
(e.g. MCU PV) is sampled every 5 seconds and then averaged at the end.
The averaged value is then logged.
An interval value of 15 minutes will log the averaged value at 15-minute
intervals, which equates to 50 days elapsed time.
P591: Fast Log Mode
If the (logged) parameter value exceeds a user-entered value (P591), model
3493 automatically moves to a fast log mode and then logs the PV once every
minute until the (logged) parameter value falls below that user-entered value.
Fast log values are tagged, and so are easily identified when examining
logged data.
P593: Low Memory Alarm
The user may allocate an alarm to indicate when the memory remaining falls
to a user-defined percentage (P593). The user must also set the action to be
taken when this occurs. A choice of activating a relay, driving the output
current to a set level, or doing both is available (P542).
If no action is taken, the memory will fill, and then logged data will either be
overwritten or the logging will stop, as determined by parameter P592.
Parameter D846 shows the percentage of free memory remaining for data
logging.
P592: Do/Do not Overwrite Old Data
Once the logging memory is full, there is a choice to continue logging, in
which case the earliest data is overwritten, or logging may be stopped at that
time.