181-122018_THCD-101 Instruction Manual
Page 12 of 26
subsequent readings. Ensure any process value to be zeroed, is in fact truly zero before performing this
function. This would mean isolating flow devices or fully pumping a pressure device.
Note that the user communicating with the THCD-101 unit remotely using the USB or Ethernet communication
ports can also clear a previously entered user re-zero value. This should be used before any input calibration is
performed to ensure that the calculated calibration points are not distorted by the user zero offset.
3.1.4. Adaptive Filtering
The THCD-101100 includes an adaptive averaging filter on the display and remote communication readings to
aid in ‘smoothing out’ unwanted ‘noise’ on the displayed readings.
(a) Operational band
The filter can be configured to filter values that are within a certain band, meaning that excursions between
subsequent readings that fall outside that band are shown as non-filtered readings. The band is configurable
between 0.01% and 1.00% of the full-scale range of the input channel. The filter can be set to OFF, which
means that no filtering is performed and can be set to ON which means that filtered value is always shown, no
matter how big of an excursion occurs.
(b) Filter size
The size of the filter is currently configurable between 0 and 6 seconds and simply indicates the amount of
readings that are taken and buffered to calculate and show the averaged reading. A filter size of 0 will
naturally turn off the filtering, irrespective of the band setting. If the buffer size is greater than 5 seconds,
filter is turned ON, meaning that filtered data will always be shown.
3.1.5. Analog Output
The analog process measurement input value received from the attached sensor is retransmitted to the user
and available on the Interface Socket. This output can be used for data logging purposes or for providing an
external setpoint control to another THCD-101 or similar instrument.
3.1.6. Alarm Relays
The THCD-101 has two internal alarm relays. Each relay has Common, Normally Open, and Normally Closed
contact connections available on the Interface Socket. Each relay will switch positions when the displayed
process variable changes from below the previously set Trip Point value to above the Trip Point + the Hysteresis
value. The relay will change back when the process value drops below the Trip Point – the Hysteresis value.
Front Panel Interface
(a) Main Screen (not changing Setpoint)
The main screen shows the main channel
input data (with range, full-scale and
calibration applied) and the associated
units string. If an input is over range (more
than 15% above full-scale voltage) then the
data value is replaced with the over range
error – “RANGE”. This screen also shows the
current mode of the setpoint, if not in
AUTO (i.e. OPEN or CLOSE). If either of the
relays have been tripped then they are also
indicated as such on the far right of the
screen.
Switch Functions:
