Using OME-DB-8225 CJC Output | Omega OME-A822PG specs

2.10Using OME-DB-8225 CJC Output

The OME-DB-8225 daughter board contains built-in cold junction compensation (CJC) circuitry that provides a 10mV per Deg C output. With 0.0 Volts @ -273 Deg C. The OME-A-822 should be protected from drafts and direct sunlight in order to accurately reflect room temperature.

CJC Calibration:

1.Connect the OME-A-822PGL/PGH to the OME-DB-8225 CN1

2.Set the OME-A-822PGL/PGH to single-ended Mode

3.Set the JP1 jumper to 1-2 and the JP2 jumper to 2-3 ( single-ended mode) 4.Read the temperature from a digital thermometer placed near D1/D2(See the

OME-DB-8225 Layout) .

5.Read OME-A-822PGL/PGH analog input channel 0 (single-ended Channel 0) 6.Adjust VR1 until a stable reading of 10mV per deg C is attained .

For example, when the ambient temperature is 24 deg C. the reading value of CJC will be 2.97V

(273 deg c +24 deg c ) X 10 mV/deg c = 2.97V

You will need an A/D channel for the CJC calibration. AI0 is reserved for CJC calibration when used in single-ended mode and CH0-HI & CH0-LO is reserved for the differential mode. differential mode is recommended when working with thermocouples.

OME-A-822PGL/PGH Hardware Manual ---- 36

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Omega OME-A822PG manual Using OME-DB-8225 CJC Output

Contents

User’sGuide Benelux CanadaMexico Czech Republic OME-A-822PGH/PGL Tables of Contents Introduction Connector Features General Description Analog Inputs SpecificationsPower Consumption 3 A/D Converter Interrupt Channel DA ConverterDigital I/O Programmable Timer/Counter Direct Memory Access Channel DMA Applications Product Check List Hardware Configuration Board Layout I/O Base Address Setting Default base address is Jumper Settings 1 JP1 D/A Internal Reference Voltage Selection 2 JP2 D/A Int/Ext Ref Voltage Selection 3 JP3 Single-ended/Differential Selection 4 JP4 A/D Trigger Source Selection 5 JP5 Interrupt Level Selection 6 JP6 User Timer/Counter Clock Input Selection 7 JP7 DMA Dack Selection JP8 DMA DRQ Selection DRQ JP7 Dack JP8 DMA I/O Register Address Address Read Write Conversion is completed, the Ready bit will clear to zero 1 8254 Counter2 A/D Input Buffer Register 3 D/A Output Latch Register 4 D/I Input Buffer Register Clear Interrupt Request 6 A/D Gain Control Register GAIN3 GAIN2 GAIN1 GAIN0 OME-A-822PGH Gain Control Code Table 7 A/D Multiplex Control Register 8 A/D Mode Control Register 9 A/D Software Trigger Control Register 10 D/O Output Latch Register Digital I/O CN2 8254 Timer/Counter Counter A/D Conversion 1 A/D conversion flow Polling, interrupt and DMA 2 A/D Conversion Trigger Modes 3 A/D Transfer Modes Refer to Sec Using software trigger and polling transferDelay the settling time refer to Sec .4.6 and Sec D/A Conversion Analog Input Signal Connection OME-A-822PGL/PGH Hardware Manual OME-A-822PGL/PGH Hardware Manual Signal Shielding Use a single connection to frame ground not A.GND or D.GND Using OME-DB-8225 CJC Output CN2 Digital Output Pin Assignment CN1/CN2/CN3 Pin AssignmentCN1 Digital Input Pin Assignment SINGLE-ENDED Signal Mode Differential Signals OME-DB-37 Daughter BoardOME-DB-8225 OME-DB-16P Calibration Description of Variable Resistors D/A Calibration A/D Calibration Diagnostic Utility Introduction OME-A-822PGL/PGH Hardware Manual Running The Diagnostic Utility Setup Base address selection screen DMA no and IRQ no selection screen Calibration Function Test Test Test Screen Digital I/O Test Screen Multiplexer Test Screen Use IRQ Test Screen Use DMA Test Screen DA Gain Test Screen Timer 0 Test Screen Special Test Help WARRANTY/DISCLAIMER Temperature