Campbell-scientific CR3000 Micrologger Uživatelský manuál stáhnout pdf (Strana 296)

Section 8. Operation

296



If this rate of update for measurement channels is too slow, the Calibrate()

instruction can be used. The Calibrate() instruction computes the necessary G

and B values every scan without any low-pass filtering.

For a VoltSe() instruction, B is determined as part of self-calibration only if the

parameter MeasOff = 0. An exception is B for VoltSe() on the ±2500 mV input

range with 250 μs integration, which is always determined in self-calibration for

use internally. For a VoltDiff() instruction, B is determined as part of self-

calibration only if the parameter RevDiff = 0.

VoltSe() and VoltDiff() instructions, on a given input range with the same

integration durations, utilize the same G values but different B values. The 5

input-voltage ranges (±5000 mV, ±1000 mV, ±200 mV, ±50 mV, ±20 mV) along

with the three different integration durations (250 μs, 50-Hz half-cycle, and 60-Hz

half-cycle) result in a maximum of 15 different gains (G), and 15 offsets for

VoltSe() measurements (B), and 15 offsets for VoltDiff() measurements (B) to be

determined during CR3000 self-calibration (maximum of 45 values). These

values can be viewed in the Status table, with entries identified as listed in table

Status Table Calibration Entries

(p. 296).

Automatic self-calibration can be overridden with the Calibrate() instruction,

which forces a calibration for each execution, and does not employ any low-pass

filtering on the newly determined G and B values. There are two parameters

associated with the Calibrate() instruction: CalRange and Dest. CalRange

determines whether to calibrate only the necessary input ranges for a given

CRBasic program (CalRange = 0) or to calibrate all input ranges (CalRange  0).

The Dest parameter should be of sufficient dimension for all the returned G and B

values, which is a minimum of two for the automatic self-calibration of VoltSE()

including B (offset) for the ±5000 mV input range with first 250 µs integration,

and a maximum of 45 for all possible integration durations and input-voltage

ranges chosen.

An example use of the Calibrate() instruction programmed to calibrate all input

ranges is given as:

'Calibrate(Dest,Range)

Calibrate(cal(1),true)

where Dest is an array of 45 variables, and Range ≠ 0 to calibrate all input ranges.

Results of this command are listed in the table Calibrate() Instruction Results

(p.

298).

Table 61. Status Table Calibration Entries

Descriptions of Status Table Elements

Status Table

Element

Differential (Diff)

Single-Ended (SE)

Offset or Gain

±mV Input

Range

Integration

CalGain(1) Gain 5000 250 ms

CalGain(2) Gain 1000 250 ms

CalGain(3) Gain 200 250 ms

CalGain(4) Gain 50 250 ms

CalGain(5) Gain 20 250 ms

1 2 ... 291 292 293 294 295 296 297 298 299 300 301 ... 589 590

Komentáře k této Příručce

Žádné komentáře

Campbell-scientific CR3000 Micrologger Uživatelský manuál Strana 296

Komentáře k této Příručce

Související produkty a manuály pro Měřící nástroje Campbell-scientific CR3000 Micrologger