Omega Engineering OMB-CHARTSCAN 1400 User Manual page 123

4. Type
5. Enter commands similar to those in the first two columns in the following table. This example is for a
T/C card in slot #1, and a Type 3 ("T" type) thermocouple. The table on the preceding page provides
additional channel numbers to use as they apply to your system.
Enter:
Note: The number after the J is the channel number, the next number is the thermocouple "type," and the
Response codes and meanings applicable to calibration are as follows:
Response to
7. Verify calibrated temperature using one of the following three options. Note related figure on
following page.
a) Cold Cell Method. Connect Cold Cell simulator to the T/C card's 4 CJC reference channels and to the
DC voltage calibrator, as indicated in the following illustration, figure (a). Adjust the calibrator
voltage to match that of the desired test temperature using Voltage-to-Temperature Reference Tables.
Verify the channel readings match the test temperature for each of the four CJC reference channels.
Repeat verification for all T/C cards.
Note: The Cold Cell Simulator in figure (a) shows a special connection box attached to it. This
b) Hot Cell Method. Connect Hot Cell simulator to T/C card's first CJC reference channel. Adjust Hot
Cell to obtain desired test temperature and ensure temperature is stabilized. Observe channel reading
to match test temperature. Repeat test for remaining three CJC reference channels. Repeat verification
for all T/C cards.
c) T/C Calibrator Method (see note). Connect a thermocouple calibrator/simulator to the first
ChartScan, or NetScan, CJC channel in accordance with the calibrator/simulator manufacturer's
instructions. Certain simulators will require the use of specific type T/C extension wire to create a
cold junction at ChartScan's, or NetScan's, input; while other simulators require copper wire and
reduce the output voltage as a function of ambient temperature to create the effect of a cold junction at
the main unit. Adjust the output setting to the desired temperature and verify the channel reading is
within the range of ChartScan's, or NetScan's, tolerance band for the T/C type and temperature.
Repeat test for remaining three CJC reference channels. Repeat this test for all thermocouple type
signal conditioning cards.
ChartScan User's Manual
to verify calibration mode.
U2X
After each calibration enter
J3,3,0000.0X
then observe
J6,3,0000.0X
J11,3,0000.0X
J14,3,0000.0X
number preceding the X is the temperature in °C. Thus, J3,3,0000.0X means "Calibrate cold
junction offset for channel 3, type 3 (T-type) thermocouple at 0°C.
Indication for Calibration Mode
U2X
No error
U128
Read Failure (EEPROM Error)
U129
Write Failure (EEPROM Error)
U130
Chksum Err (EEPROM Error)
U132
Cal Err (offset, gain, or temperature sensor out of range)
U136
Invalid password
U144
Invalid command
U160
connection box, which can be easily made, is not part of the cold cell device.
The T/C Calibrator/Simulator Method is not recommended because, unlike voltage
calibrators, T/C Calibrator/Simulators have no provisions for remote sensing (and are
therefore more readily subject to the transient effects of sampled data acquisition
systems, such as ChartScan and NetScan). These transient effects can cause erroneous
readings, even when both units are calibrated within specifications.
should appear, indicating the unit is in calibration mode.
U128
,
U2X
indicating no errors.
U128
Calibration 6-19