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Hysteresis, Span
Same relay operation as for split hysteresis,
but specified differently. Here the setpoint is
the upper control limit, and the lower control
limit is the setpoint less the hysteresis band.
Menu Mode The meter programming mode used for input
and range selection, meter setup, and meter
configuration. Entered into from the Run mode
by pressing the MENU key. The Menu mode
can be locked out completely by a jumper.
Meter Hold A rear panel input which freezes the meter display and all meter outputs while
that input is tied to logic ground by a switch or is held at 0V (resume operation
when the input is allowed to float or is held at +5V (logic level false).
Meter Reset Causes the meter to reinitialize and take a tare reading when set up for auto-
tare. Takes about 2-3 sec. rESEt is displayed briefly. Achievable by removing
and reapplying power to the meter, by simultaneously pressing the RESET and
MENU keys, by supplying an ASCII command, by stepping through all top-level
menu choices, or by grounding a rear panel control input 1 or 2 if so programmed
under Setup.
Modbus An industry-standard serial communications protocol which allows devices by
different manufacturers to be digitally addressed by a PC on the same commu-
nication line, with up to 247 digital addresses. More complex than the Custom
ASCII protocol, which is also supported by these meters.
Moving Average Filter
A digital filter mode which displays a weighting moving average of readings.
Readings are taken at 60/sec with 60 Hz power and 50/sec with 50 Hz power.
Display update rates remain 3.5/sec with 60 Hz power and 3.0/sec with 50 Hz
power. There are eight moving average modes:
▪ Old average x 1/2 + new reading x 1/2 (equivalent to 0.08 sec RC time constant).
▪ Old average x 3/4 + new reading x 1/4 (equivalent to 0.15 sec RC time constant).
▪ Old average x 7/8 + new reading x 1/8 (equivalent to 0.3 sec RC time constant).
▪ Old average x 15/16 + new reading x 1/16 (equivalent to 0.6 sec RC time constant).
▪ Old average x 31/32 + new reading x 1/32 (equivalent to 1.2 sec RC time constant).
▪ Old average x 63/64 + new reading x 1/64 (equivalent to 2.4 sec RC time constant).
▪ Old avg. x 127/128 + new reading x 1/128 (equivalent to 4.8 sec RC time constant).
▪ Old avg. x 255/256 + new reading x 1/256 (equivalent to 9.6 sec RC time constant).
Offset A constant adder used for the displayed reading. This is the term b in the straight
line formula y = mx + b, where y is the displayed reading in counts, m is the
scale factor, x is the measured reading in counts, and b is the offset. For direct
readout in (milli)volts or (milli)amps, offset is 0.
Peak Display The maximum (or most positive) reading since that maximum was last reset.
Reset can be via the meter front panel, an external input, or a software command.
The displayed value can reflect the filtered or unfiltered readings.
Process Signal A signal whose display requires setup of scale and offset settings for display
in engineering units. A classical process signal is 4-20 mA, where the 4 mA and
20 mA end points can each correspond to a desired meter reading.
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