Specifications

Halogen Gas Monitor – MultiZone Remote Display
Instruction 3015-5157 37
The Trend Screen
Overview - Log Interval
The HGM-MZ retains a data log of 100 measurements for each zone. The log interval is the number of
minutes from 1 to 1440 between each log point. This parameter can be changed from Zone Setup Screen
#1 (Page 27).
The default setting for this parameter is 1440 minutes (24 hours). If the log interval time is set to 0, then a
measurement is recorded in the trend log after every measurement cycle. Therefore, after the trend log is
filled it will contain the last 100 measurement points for a zone. If you want the data logged less frequently
you should increase this value. It is important to remember that cycle time is dependent on many factors,
including the number of zones being monitored, input line length, and the run zeroing mode selected. Before
changing this value it may be useful to first review the log data using the Trend Screen to determine the
nominal cycle time.
Navigating to the Trend Screen
Access the Trend Screen from the Zone Screen as follows:
From the top level Zone Screen (Page 30) press the key adjacent to the zone you wish to work with to first
display its Zone Setup Screen #1. Then press the TREND key at the bottom of the display to go to the
Trend Screen.
Trend Screen
The trend graph opens with the cursor located over the most recent data point. Use the LEFT/RIGHT cursor
keys to move the cursor to different data points. Holding a key down will cause cursor to move rapidly across
the screen. As you move the cursor position, the date and time of that reading, along with the PPM value, are
displayed at the top of the screen above the graph. The trend graph is automatically scaled to accommodate
the largest PPM value displayed. The ZOOM OUT and ZOOM IN options, located in the bottom corners of
the screen, allow you to adjust the vertical scale of the graph.
The trend data is stored on a first-in, first-out basis. After 100 trend values have been stored the 101
st
value
will replace the first value stored. Therefore, in normal operation, when entering trend mode the cursor will be
located at the most recent data point. The data points to the left of the initial cursor location will be the next
most recent. The data point to the right will be the oldest data point in the buffer and will be over written by
the next data point.