Multiple Choice Questions & Answers on 8051 Microcontroller I/O Port Programming and Addressing Modes 1. Which operator is the most important while assigning any instruction as register indirect instruction? a) $ b) # c) @ d) & Answer: @ 2. Which of the following comes under the indexed addressing mode? a) MOVX A, @DPTR b) MOVC @A+DPTR,A c) MOV A,R0 d) MOV @R0,A Answer: MOVC @A+DPTR,A 3. Which out of the four ports of 8051 needs a pull-up resistor for using it is as an input or an output port? a) PORT 0 b) PORT 1 c) PORT 2 d) PORT 3 Answer: PORT 0 4. Which of the ports act as the 16 bit address lines for transferring data through it? a) PORT 0 and PORT 1 b) PORT 1 and PORT 2 c) PORT 0 and PORT 2 d) PORT 1 and PORT 3 Answer: PORT 0 and PORT 2 5. Which instruction is used to check the status of a single bit? a) MOV A,P0 b) ADD A,#05H c) JNB PO.0, label d) CLR P0.05H Answer: JNB PO.0, label 6. Which of the following registers are not bit addressable? a) SCON b) PCON c) A d) PSW An...

Multiple Choice Questions & Answers on 8051 Microcontroller Interrupt Programming 1. Which pin of the external hardware is said to exhibit INT0 interrupt? a) pin no 10 b) pin no 11 c) pin no 12 d) pin no 13 Answer: pin no 12 2. What are the contents of the IE register, when the interrupt of the memory location 0x00 is caused? a) 0xFFH b) 0x00H c) 0x10H d) 0xF0H Answer: 0x00H 3. Which of the following combination is the best to enable the external hardware interrupt 0 of the IE register (assuming initially all bits of the IE register are zero)? a) EX0=1 b) EA=1 c) any of the mentioned d) EX0=1 & EA=1 Answer: EX0=1 & EA=1. 4. Which bit of the IE register is used to enable TxD/RxD interrupt? a) IE.D5 b) IE.D2 c) IE.D3 d) IE.D4 Answer: IE.D4 5. What is the correct order of priority that is set after a controller gets reset? a) RI/TI > TF1 > TF0 > INT1 > INT0 b) RI/TI < TF1 < TF0 < INT1 < INT0 c) INT0 > TF0 > INT1 > TF1 > RI/TI d) INT0 < TF...

  Light Dependent Resistor (LDR)  Working Principle of Light Dependent Resistor (LDR) Light Dependent Resistor work based off of the principle of photoconductivity. Photoconductivity is an optical phenomenon in which the material’s conductivity is increased when light is absorbed by the material. When light falls i.e. when the photons fall on the device, the electrons in the valence band of the semiconductor material are excited to the conduction band. These photons in the incident light should have energy greater than the bandgap of the semiconductor material to make the electrons jump from the valence band to the conduction band. Hence when light having enough energy strikes on the device, more and more electrons are excited to the conduction band which results in a large number of charge carriers. The result of this process is more and more current starts flowing through the device when the circuit is closed and hence it is said that the resistance of the device has been de...

Multiple Choice Questions & Answers on 8051 Microcontroller  Serial Port Communication 1. With what frequency UART operates( where f denoted the crystal frequency )? a) f/12 b) f/32 c) f/144 d) f/384 Answer: f/384 2. What is a null modem connection? a) no data transmission b) no MAX232 c) the RxD of one is the TxD for the other d) no serial communication Answer: the RxD of one is the TxD for the other 3. What should be done if we want to double the baud rate? a) change a bit of the TMOD register b) change a bit of the PCON register c) change a bit of the SCON register d) change a bit of the SBUF register Answer: change a bit of the PCON register 4. Which of the following signal control the flow of data? a) RTS b) DTR c) RTS & DTR d) None of the mentioned Answer: RTS 5. Which of the following best describes the use of framing in asynchronous means of communication? a) it binds the data properly b) it tells us about the start and stops of the data to be transmitted or receive...

Multiple Choice Questions & Answers on 8051 Microcontroller LCD and Keyboard Interfacing 1. The RS pin is _________ for an LCD. a) input b) output c) input & output d) none of the mentioned Answer: input 2. How many data lines are there in a 16*2 alphanumeric LCD? a) 16 b) 8 c) 1 d) 0 Answer: 8 3. In reading the columns of a matrix, if no key is pressed we should get all in binary notation a) 0 b) 1 c) F d) 7 Answer: 1 4. Which pin of the LCD is used for adjusting its contrast? a) pin no 1 b) pin no 2 c) pin no 3 d) pin no 4 Answer: pin no 3 5. How many rows and columns are present in a 16*2 alphanumeric LCD? a) rows=2, columns=32 b) rows=16, columns=2 c) rows=16, columns=16 d) rows=2, columns=16 Answer: rows=2, columns=16 6. Which command is used to select the 2 lines and 5*7 matrix of an LCD? a) 0x01 b) 0x06 c) 0x0e d) 0x38 Answer: 0x38 7. Which instruction is used to select the first row first column of an LCD? a) 0x08 b) 0x0c c) 0x80 d) 0xc0 Answer: 0x80 8. Which command of...

Multiple Choice Questions & Answers on 8051Microcontroller ADC, DAC Interfacing 1. 8 input DAC has ________ a) 8 discrete voltage levels b) 64 discrete voltage levels c) 124 discrete voltage levels d) 256 discrete voltage levels Answer: 256 discrete voltage levels 2. What is the function of the WR pin? a) its active high input used to inform ADC0804 to the end of conversion b) its active low input used to inform ADC0804 to the end of conversion c) its active low input used to inform ADC0804 to the start of conversion d) its active high input used to inform ADC0804 to the start of conversion Answer: its active low input used to inform ADC0804 to the start of conversion 3. State which of the following statements are false? a) CLK IN pin used for External Clock Input or Internal Clock with external RC element b) INTR pin tells about the end of the conversion c) ADC0804 IC is an 8 bit parallel ADC in the family of the ADC0800 series d) None of the mentioned Answer: None of the mentio...

Multiple Choice Questions & Answers on Key Enablers of Industrial IoT   1. SIGFOX radio link operates on _____________. a) Both licensed and unlicensed ISM band b) Only licensed ISM band c) Only unlicensed ISM band d) None of the above Answer: Only unlicensed ISM band 2. Coordinator ZigBee devices act as the bridge between ______. a) Different networks b) Different edge devices c) Different fog devices d) All of the above Answer: Different networks 3. The architectural layers of SmartSantander include __________. a) Accessible, Authorization, and Accounting subsystem b) Authentication, Authorization, and Accounting subsystem c) Authentication, Authorization, and Accomodation subsystem d) None of the above Answer: Authentication, Authorization, and Accounting subsystem 4. Smart warehousing uses ____________-based framework. a) Both RIFT and RIST b) Only RIFT c) Only RIST d) Only REST Answer: Only REST 5. A typical industrial control system includes _____________ major componen...

Safety Instrumented Function and Safety Instrumented System Safety Instrumented Function A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific safety-related task in the event of a specific dangerous condition. The over-temperature shutdown switch inside a clothes dryer or an electric water heater is a simple, domestic example of an SIF, shutting off the source of energy to the appliance in the event of a detected over-temperature condition. Safety Instrumented Functions are alternatively referred to as Instrument Protective Functions, or IPFs.  The safety instrumented function is a control loop in a process or machine whose objective is safety. SIF is its acronym in English. In the following image we see the most common simplified representation of the SIF. The integrity and performance of the safety instrumented function depends on a large number of factors, and it is measured by the so-called “Safety Integrated Level” (SIL) which a...

Level troll A Level troll in and instrument used for measuring the liquid level between two known points. The Level troll works on the buoyancy principal. Leveltrol has a float, which submerses proportionately with liquid level raise in the float chamber. The amount of submersion of the dis placer depends on the liquid density, which produces a torque. The amount of torque produced in measured in terms of % of level. Parts of Level troll Float chamber Float Torque lever Knife edge  Feedback Bellows Air Relay Restriction Flapper Nozzle Feedback link Density range Action change lever HP and LP flange

Process Variables What are the Process Variables? Answer: The process variables are Flow. Pressure. Temperature. Level. Quality i.e. % O2, CO2, pH etc. Define all the process Variable and state their unit of measurement. ? Answer:  Flow Any fluids or liquids flowing from one place to another place is called flow and it is defined as volume per unit of time at specified temperature and pressure .Conditions, is generally measured by positive-displacement or rate meters. Units:- kg / hr, litter / min, gallon / min, m3 / hr, Nm3 / hr. (Gases) Pressure It is defined as Force per unit Area. P = F/A Units:- bar, Pascal, kg / cm2, lb / in2. Level The height of the water column, liquid and powder etc., at the desired measurement of height between minimum level points to maximum level point is called level. The measurement principle is, head pressure method. Units:- Meters, mm, cm, percentage. Temperature It is the degree of hotness or coldness of a body is called temperature. Units:- Deg...

Documents and drawings, which is essential for instrumentation engineer. As an instrumentation engineer, one must be familiar with the following documents and drawings. Documents Instrument index. Instrument data sheet Cable schedule Bill of material. Drawing JB & Instrumentation location drawing. GA Drawings. Piping instrument drawing. Hook up drawing Documents Instrument index An instrument index is a consolidated list of all instruments which is used in the plant. Instrument index is made according to the P&ID. In this all instruments tags are listed in an orderly manner. It consists of following details. Type of instrument. Location of an instrument. Installation standard. Data sheet Data sheet is a document which contains information about the performance and characteristics of an instrument.  Cable schedule We can categorise the cables in to two type Primary cables and Secondary cables. Primary cables Cable which is laid between junction box and control room is cal...

Instrumentation Instrumentation=measure+control. It measure the parameters which helps the process and control the process. The basic parameters associated with process are temperature,flow level and measure. Origin of instrumentation. Instrumentation is the combintion of electrical,mechanical and electronics. In the first stage of instrumentation the connection between the instrument and controller were mechanical(Pneumatic connection). In pneumatic connection 3-15 psi pressure was used as signal. In 1970’sindustries started to using electrical connection between instrument and controller instead of pneumatic connection. Two types of signals are using in electrical transmission. Analog Digital Analog Signal signal which varies continously with time. From the real world itsel we can found out so many examples for analog signals. Sound,light etc.. But in the case of instrumentaton we are using 4-20 ma or 0-20 ma as analog signals. Here the voltage between controller and instrume...

Hot Water System And Loops Hot-Water Systems Hot-water systems use hot water to convey heat to a conditioned space. This is done using suitable heat transfer units located in the duct work or in the conditioned space. Hot-water heating systems are also called hydronic heating systems. Water Temperature Hot-water systems vary in the temperature of supply water provided and can be classified as follows Low temperature systems operate below 250° F and maintain a typical operating pressure of about 30 psi. Specifically designed low temperature water systems rated for higher pressures may be used up to 160 psi. Medium temperature systems operate at temperatures below 350°F with pressures not exceeding 150 psi. The usual water supply temperature is 250 to 325° F with a pressure rating of 150 psi. High temperature systems operate below 450° F with pressures not exceeding 300 psi. Typical operating temperatures are over 350° with pressure around 300 psi.  Each component in the high tempera...

Root Locus Effect of Addition of zeros and poles Addition of zeros The addition of a zero to the open-loop transfer function has the effect of pulling the root locus to the left, tending to make the system more stable and to speed up the settling of the response.  Physically, the addition of a zero in the feed forward transfer function means the addition of derivative control to the system. The effect of such control is to introduce a degree of anticipation into the system and speed up the transient response. The Figure 1(a) shows the root loci for a system that is stable for small gain but unstable for large gain.  Figures 1(b), (c), and (d) show root-locus plots for the system when a zero is added to the open-loop transfer function. It becomes stable for all values of gain. However, it is not possible to add an isolated zero to a transfer function because of physical non-realizability. Therefore, in order to realize the compensating network a pair of pole-zero has to be inco...

root-locus Approach The root-locus method is a graphical method for determining the locations of all closed-loop poles from knowledge of the locations of the open-loop poles and zeros as some parameter (usually the gain) is varied from zero to infinity. The method yields a clear indication of the effects of parameter adjustment. In practice, the root-locus plot of a system may indicate that the desired performance cannot be achieved just by the adjustment of gain.  In fact, in some cases, the system may not be stable for all values of gain. Then it is necessary to reshape the root loci to meet the performance specifications. In designing a control system, if other than a gain adjustment is required, we must modify the original root loci by inserting a suitable compensator.  Once the effects on the root locus of the addition of poles and/or zeros are fully understood, we can readily determine the locations of the pole(s) and zero(s) of the compensator that will reshape the root...