Monarch Instrument DC 2000 - Manual (Page 80)

Page 5-14
Chapter 5 Programming
5.6.5.6 Filter
The digital filter smooths noisy or erratic signals by attenuating the effects of sudden transitions. The
digital filter is programmable from 0 to 30 seconds in one second increments (nominal).
Programming Filter Seconds - Use the UP (
↑) or DOWN (↓) Arrow Keys to scroll through the menu
items in the Point Setup Menu and highlight “Filter”. Press ENTER and the display reads “seconds ÎXXÍ.
Use the numeric keypad to enter the required number of seconds (maximum 30) then press ENTER to
return to the “Filter” menu item.
5.6.5.7 Compensation
Thermocouple compensation can be local, from the cold reference junction temperature sensor built into
the Recorder, or external through a direct input. When thermocouples are compensated locally, the
temperature sensor (located on the rear terminal panel of the Recorder) measures the ambient
temperature of the cold junction. For remote compensation, a single Thermocouple or RTD can be used to
measure the ambient temperature of the remote junction box. This method allows several thermocouple
points to be measured without using thermocouple extension wire for each input. The point used as the
measurement source of the remote cold junction source is referred to as the compensation channel.
The point used as the compensation channel must be programmed before the Thermocouple or RTD input
is assigned to it. When the system prompts for compensation parameters, the UP (
↑) or DOWN (↓) Arrow
Key allows you to define this parameter (local or remote). Once thermocouple compensation has been
set, continue the programming sequence.
Programming Compensation - Use the UP ( ↑) or DOWN (↓) Arrow Keys to scroll through the menu
items in the Point Setup Menu and highlight “Compensation” and press ENTER. Use the UP ( ↑) or DOWN
(
↓) Arrow Keys to highlight either “Local comp” or “Ext comp”. If “Local comp” is chosen, press ENTER and
the display returns to the “Compensation” prompt in the Point Setup Menu. If “Ext comp” is chosen, press
ENTER and the display prompts for “ext point? X”. Use the UP (
↑) or DOWN (↓) Arrow Keys to scroll
through the point numbers to choose the input where the external compensation is input. When the
desired point number is displayed, press ENTER and the display returns to the “Compensation” menu item
in the Point Setup Menu.
5.6.5.8 Span/Offset
In order for the Span/Offset menu option to be available, the user must turn this feature on in the
Measurement Program menu, refer to Section 5.8.2, Span and Offset. Once this option has been turned
on, the user can use Span and Offset to compensate for long thermocouple cable runs or thermocouple
inaccuracies. The default value for offset is 0 and the default value for span is 1. The offset is a value of
absolute degrees which is added or subtracted to the thermocouple reading. The span is a multiplier of the
absolute thermocouple range. Once span and offset have been entered, the new adjusted range will be
New T/C Range = (Full Scale * SPAN) + OFFSET
Note that span is a multiplier while offset is an additive.
To adjust the span and offset (this assumes this option has been turned on in the Measurement menu) use
the UP (
↑) or DOWN (↓) Arrow Keys in the Thermocouple option menu to select Span/Offset and press
ENTER. The display will show “Ofs → 0.0000←”. Use the numeric keys to enter a value for the offset
which will be added or subtracted to the thermocouple value. Note that offset is typically measured around
the ice point which should be 0° C or 32°F. The offset would be typically the difference between the
thermocouple reading at this point and the true ice point value. Press ENTER. The display will then show
“Spn
→ 1.00000←”. Use the numeric keypad to enter the new span value. The span should typically be
measured near the full scale value of the thermocouple using a known temperature or reference. The
span would be the absolute value of the reference divided by the reading of the thermocouple. Press
ENTER to register these values and return to the Thermocouple option menu.