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

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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.

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Contents User’sGuide Benelux CanadaMexico Czech RepublicOME-A-822PGH/PGL Tables of Contents IntroductionConnector Features General DescriptionAnalog Inputs SpecificationsPower Consumption 3 A/D ConverterInterrupt Channel DA ConverterDigital I/O Programmable Timer/Counter Direct Memory Access Channel DMAApplications Product Check ListHardware Configuration Board LayoutI/O Base Address Setting Default base address isJumper Settings 1 JP1 D/A Internal Reference Voltage Selection2 JP2 D/A Int/Ext Ref Voltage Selection 3 JP3 Single-ended/Differential Selection4 JP4 A/D Trigger Source Selection 5 JP5 Interrupt Level Selection6 JP6 User Timer/Counter Clock Input Selection 7 JP7 DMA Dack Selection JP8 DMA DRQ Selection DRQ JP7 Dack JP8 DMAI/O Register Address Address Read WriteConversion 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 Request6 A/D Gain Control Register GAIN3 GAIN2 GAIN1 GAIN0OME-A-822PGH Gain Control Code Table 7 A/D Multiplex Control Register8 A/D Mode Control Register 9 A/D Software Trigger Control Register 10 D/O Output Latch Register Digital I/O CN28254 Timer/Counter CounterA/D Conversion 1 A/D conversion flow Polling, interrupt and DMA2 A/D Conversion Trigger Modes 3 A/D Transfer ModesRefer 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.GNDUsing 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-16PCalibration Description of Variable ResistorsD/A Calibration A/D Calibration Diagnostic Utility IntroductionOME-A-822PGL/PGH Hardware Manual Running The Diagnostic Utility Setup Base address selection screenDMA 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