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Standard Commands for Programmable Instruments(SCPI)

FROM WIKIPEDIA: The  Standard Commands for Programmable Instruments (SCPI)  (often pronounced "skippy") defines a standard for syntax and commands to use in controlling programmable test and measurement devices. Overview In 1990, SCPI became defined with the  IEEE 488.2  specification. The standard specifies a common  syntax ,  command  structure, and  data formats , to be used with all instruments. It introduced generic commands (such as  CONFigure  and  MEASure ), which could be used with any instrument. These commands are grouped into subsystems. SCPI also defines several classes of instruments. For example, any controllable  power supply  would implement the same  DCPSUPPLY  base functionality class. Instrument classes specify which subsystems they implement, as well as any instrument-specific features. The physical communications link is not defined by SCPI. While originally created f...

GPIB-IEEE488

IEEE-488 Pin out Female IEEE-488 connector Pin 1 DIO1 Data input/output bit. Pin 2 DIO2 Data input/output bit. Pin 3 DIO3 Data input/output bit. Pin 4 DIO4 Data input/output bit. Pin 5 EOI End-or-identify. Pin 6 DAV Data valid. Pin 7 NRFD Not ready for data. Pin 8 NDAC Not data accepted. Pin 9 IFC Interface clear. Pin 10 SRQ Service request. Pin 11 ATN Attention. Pin 12 SHIELD Pin 13 DIO5 Data input/output bit. Pin 14 DIO6 Data input/output bit. Pin 15 DIO7 Data input/output bit. Pin 16 DIO8 Data input/output bit. Pin 17 REN Remote enable. Pin 18 GND (wire twisted with DAV) Pin 19 GND (wire twisted with NRFD) Pin 20 GND (wire twisted with NDAC) Pin 21 GND (wire twisted with IFC) Pin 22 GND (wire twisted with SRQ) Pin 23 GND (wire twisted with ATN) Pin 24 Logic ground Advantages Simple hardware interface Ease of connecting multiple device to a single host Allows mixing of slow and fast devices Well-established and mature, widely supported Rugged...

PEP IMPORTANT Q's

FIRST UNIT  Classify chemical industries   Flow charts types - explain *   Define  moles, ideal gas law   Principle involved in material & Energy Balances*  What is Rate? Equilibrium?  What is vapour pressure?What is the effect of the temperature on vapour pressure?   SECOND UNIT What is viscosity? What is shear stress? Newtonian  &Non Newtonian fluids.Eg.* Laminar Flow,Turbulent flow. What is cavitation? What are the different types of pumps?* Explain    Mechanical Operation? Jaw crusher -        Principle of working Ball Mill                -        Principle of working Sieve Shaker         -        Principle of working   THIRD UNIT   Evaporation -Refer my notes   What is conduction? Give eg. Convection? Give eg. /Radiation eg.   Fouriers Law o...

Humidity Measurement

Absolute humidity If all the water vapor in one cubic meter of air were condensed into a container, the mass of the water in the container could be measured with a scale to determine absolute humidity. The amount of water vapor in that cube of air is the absolute humidity of that cubic meter of air. More technically, absolute humidity on a volume basis is the mass of dissolved water vapor,  m w , per cubic meter of total moist air,  V n e t : Absolute humidity ranges from 0 grams per cubic meter in dry air to 30 grams per cubic meter (0.03 ounce per cubic foot) when the vapor is saturated at 30 °C. The absolute humidity changes as air pressure changes. This is very inconvenient for chemical engineering calculations, e.g. for clothes dryers, where temperature can vary considerably. As a result, absolute humidity is generally defined in chemical engineering as mass of water vapor per unit mass of dry air, also known ...

Understanding Absolute and Kinematic Viscosity

        Of all the tests employed for used oil analysis, none provides better test repeatability or consistency than viscosity. Likewise, there is no property more critical to effective component lubrication than base oil viscosity. However, there is more to viscosity than meets the eye. Viscosity can be measured and reported as dynamic (absolute) viscosity or as kinematic viscosity. The two are easily confused, but are significantly different. Most used oil analysis laboratories measure and report kinematic viscosity. By contrast, most onsite viscometers measure absolute viscosity, but are typically programmed to estimate and report kinematic viscosity, so that the viscosity measurements reported reflect kinematic numbers reported by most labs and lube oil suppliers. Given the importance of viscosity analysis coupled with the increasing popularity of onsite oil analysis instruments used to screen and supplement offsite laboratory oil analysis, it is essential t...

Cold Junction Compensation

This is a  temperature measurement   circuit  using thermocouple. This is a low-frequency application . It will allow the OPA335 to be switched directly into the signal path. Thiscircuit has low noise, high accuracy, and low drift. Here is the circuit : The 4.096-V bridge supply is provided by a precision voltage  reference . A  negative temperature coefficient of  diode D1′s forward voltage is -2 mV/ºC. It also provides cold junction compensation via the  resistor  network R1 to R3. R6 is used to obtain the zero adjustment for a defined minimum temperature. The gain for the output  amplifier  is set by R8 and R7. This circuit has 16-bit or better accuracy at high gain in low-voltage applications because the single-supply amplifier provide an open loop gain of 130dB. This circuit has an auto zeroing, that is used to provide typical values of 1 µV of input offset and 20 nV/ºC of offset...

Laws of Thermocouple

The Seebeck Effect A German physician turned physicist named Thomas Johann Seebeck took two different metals, with one at a higher temperature than the other, and made a series circuit by joining them together to form a junction. He found that by doing so he was able to generate an electromotive force (emf). Emfs are voltages. Seebeck found that the larger the temperature differences between the metals, the higher the generated voltage, regardless of their shapes. His discovery is called the Seebeck effect, and it is the basis of all thermocouples. Background Seebeck, H.G. Magnus, and A.C. Becquerel proposed the empirical rules of thermoelectric circuits. Lord Kelvin explained their thermodynamic basis, and W.F. Roesser compiled them into a set of three fundamental laws. They have all been verified experimentally. The second law is sometimes broken up into three parts by modern day researchers, to give a total number of five, but Roesser's are still the standar...