Measurement Computing TempBook rev.3.0 - Manual (Page 148)

11-24 daqCommand Reference (Enhanced API) TempBook User’s Manual
daqCvtTCSetup
DLL Function daqCvtTCSetup(DWORD nscan, DWORD cjcPosition, DWORD ntc, TCType tcType, BOOL
bipolar, DWORD avg);
C daqCvtTCSetup(DWORD nscan, DWORD cjcPosition, DWORD ntc, TCType tcType, BOOL
bipolar, DWORD avg);
Visual BASIC VBdaqCvtTCSetup&(ByVal nscan&, ByVal cjcPosition&, ByVal ntc&, ByVal tcType&,
ByVal bipolar&, ByVal avg&)
Delphi daqCvtTCSetup(nscan:DWORD; cjcPosition:DWORD; ntc:DWORD; tcType:TCType;
bipolar:longbool; avg:DWORD)
Parameters
nscan The number of readings in a single scan of DaqBook/DaqBoard data. The daqCvtTC… functions can
convert several consecutive scans worth of data in a single invocation.
Valid range: 2 to 512.
cjcPosition The position of the actual cold-junction compensation circuit (CJC) reading within each scan (not the CJC
zero reading, if any). The first reading of the scan is position 0, and the last reading is nscan -1. Each
scan of temperature data must include a reading of the CJC signal on the expansion board to which the
thermocouples are attached. The CJC readings must be taken with the gain in the section Scan Setup.
Valid range: 0 to nscan-2 with no zero compensation; 2 to nscan-2 with zero compensation.
ntc The number of thermocouple signals that are to be converted to temperature values. The thermocouple
signal readings must immediately follow the CJC reading in the scan data. The first thermocouple signal
is at scan position cjcPosition+1,; the next is at cjcPosition+2,; and so on. Valid range: 1 to nscan-1-
cjcPosition.
tcType The type of thermocouples that generated the measurements. Valid range: One of the pre-defined values,
TbkTCTypeJ, TbkTCTypeK, TbkTCTypeT, TbkTCTypeE, TbkTCTypeN28, TbkTCTypeN14,
TbkTCTypeS, TbkTCTypeR or TbkTCTypeB.
bipolar Must be set true (non-zero) if the readings were acquired with the Daq* set for bipolar operation. Must be
set false (zero) for unipolar operation. The required gain settings for the CJC and thermocouple channels
change depending on the unipolar/bipolar mode. Valid range: 0 for unipolar or any non-zero value for
bipolar.
avg The type of averaging to be performed. Valid range: any unsigned integer. Since the thermocouple voltage
may be small compared to the ambient electrical noise, averaging may be necessary to yield a steady
temperature output.
0 specifies block averaging in which all of the scans are averaged together to compute a single temperature
measurement for each of the ntemp thermocouples.
1 specifies no averaging. Each scan’s readings are converted into ntemp measured temperatures for a
total of scans*ntemp results.
2 or more specifies moving average of the specified number of scans. Scan readings are averaged with the
avg-1 preceding scans’ readings before conversion. The first avg-1 scans are averaged with all of the
preceding scans because they do not have enough preceding scans. For example, if avg is 3, then the
results from the first scan are not averaged at all, the results from the second scan are averaged with the
first scan, the results from the third and subsequent scans are averaged with the preceding two scans as
shown in the table.
Returns DerrTCE_PARAM - Parameter out of range
DerrTCE_TYPE - Invalid thermocouple type
DerrNoError - No Error (also, refer to API Error Codes on page 11-39)
See Also daqCvtTCConvert, daqCvtTCSetupConvert
Program References None
Used With All devices
daqCvtTCSetup sets up parameters for subsequent temperature conversions. The next table
shows how averages are computed.
Scan Readings
from
Channel
Results from Channel
0 1 0 1
1 1A 2A 1A 2A
2 1B 2B (1A+1B)/2 (2A+2B)/2
3 1C 2C (1A+1B+1C)/3 (2A+2B+2C)/3
4 1D 2D (1B+1C+1D)/3 (2B+2C+2D)/3
5 1E 2E (1C+1D+1E)/3 (2C+2D+2E)/3
6 1F 2F (1D+1E+1F)/3 (2D+2E+2F)/3