TILI Automation

 Build the ladder logic program to turn ON or OFF the lamp using single push buttons using one shot rising (ONR) instruction. ONE Shot Rising (OSR) Instruction One shot Rising is used to develop a signal/Pulse that is exactly one scan in duration. When a signal is applied to a contact/Push Button, no matter how long the signal stays on, a single pulse of one scan length is generated after the one shot. List of Inputs and Outputs PLC Logic Conditions One Shot Rising PLC Program Program Description RUNG 0000 Start/Stop Push Button is connected with one shot rising bit with the output memory bit. RUNG 0001 Previous rung output bit and Lamp output bit are connected in X-OR gate logic to make the condition possible. Interlocking of output bit is used to turn the output ON/OFF in different condition. Conclusion: The above explained ladder logic for lamp turn ON/OFF using single push button is for example only. We can use this example program to understand the working of Push Buttons, one...

 This article discusses about ON delay timer instruction and its working principle using Allen Bradley Programmable Logic Controller (PLC) Ladder Logic. ON Delay Timer In the above On-delay timer instruction, there are totally four parameter, TIMER: T4:0 – Timer File name (Timer T4:0, T4:1, T4:2…) TIMER BASE – How the time need to count, in Seconds, Milli Seconds… PRESET – Limit value of Timer-Up to how much it should count ACCUMULATOR – Running Value of timer when it is in ON condition. Program Description ON delay timer purpose is to delaying the ON time, Example : After the turning ON of main switch, Air Conditioner takes nearly 5s to 15s to turn ON. On Delay Timer using PLC RUNG 0000 Start and Stop Switch is to turn ON/OFF the timer. RUNG 0001 When start switch is pressed, Timer Enable bit (T4:0/EN) is turned ON to show the status of TIMER ON/OFF condition RUNG 0002 When start switch is pressed, along with the timer enable bit timer timing bit also turned ON to show the status ...

 This article discusses about OFF delay timer instruction and its working principle using Allen Bradley Programmable Logic Controller (PLC) Ladder Logic. Timer OFF delay is to delaying the turning OFF of any output, Example-Setting timer to turn off Induction Stove, TV remote settings to turn OFF TV after certain time. OFF Delay Timer In the above OFF delay timer instruction, there are totally four parameter, TIMER: T4:0 – Timer File name (Timer T4:0, T4:1, T4:2…) TIMER BASE – How the time need to count, in Seconds, Milli Seconds. PRESET – Limit value of Timer-Up to how much it should count ACCUMULATOR – Running Value of timer when it is in ON condition. Program Description Off- delay timer instructions is used to program a time delay to begin after rung input goes false. As an example, when an external cooling fan on a motor is provided, the fan has to run all the time the motor is running and also for certain time (say 10 min) after the motor is turned off. This is a ten minute o...

 Supervisory control and data acquisition (SCADA) is a system of software and hardware elements that allows industrial organizations to : Controlling & monitoring Process in real time from Remote location Analyze & calculation of complex the Process & maintain accordingly the Control Signals Data Acquisition, Historical Data Logging, Archiving & retrieving Trend & Alarm generation Recipe Management for Process & Chemical Industries Report Generation Applications of SCADA SCADA is widely used in different areas from chemical, gas, water, communications and power systems. The list of applications of SCADA can be listed as follows. Electric power system, operation and control: SCADA systems are used in electric power generation plants, transmission area and distribution system. Manufacturing Industries or plants: A SCADA helps in management of different inventory items or raw materials, controlling of automated systems in synchronous manner. Telecom and IT base...

 Build the ladder logic program to turn ON and OFF the lamp using push buttons with respect to program logic conditions. PLC Lamp Control PLC Problem Logic Start PB and Stop PB are used to turn ON and OFF the lamp. It should follow the following two cases. CASE 1 : Start PB is used to turn ON the lamp, Same Start PB is thrown again to turn OFF the lamp. CASE 2 : Start PB is Pressed to turn on the Lamp, if stop PB is pressed to turn OFF the lamp, Start PB is pressed twice to turn ON the lamp again. NOTE: Both the cases should satisfy in single program using minimum number of memories. Its user choice to pick the case option. List of Inputs and Outputs PLC Lamp Program PLC Lamp Ladder Logic Description RUNG 0000 Latching rung to operate the system through Master Start and Stop PB. RUNG 0001 To store the status of start PB (When we released hand after we pressed it for first time) when lamp is in ON condition. Since we are using Push Buttons, Memory Switch B3:0/1 is connected in paral...

 To study the working of One Shot Rising (OSR) and One Shot Falling (OSF) functions in Allen Bradley programmable logic controllers (PLC). One Shot Rising and One Shot Falling Instructions In the above instruction block of One shot Rising (OSR) or One shot falling (OSF), There are two Variables, Storage Bit: This bit is to store the status of input. Output Bit: This bit store the value when it executes the function of Block One Shot Rising (OSR) One shot rising is similar to ONS except the storage and output bits. It gives single pulse at the time of going ON condition. Storage bit stores the status of input. Output bit stores the status of function performed by the block. One Shot Falling (OSF) One shot falling gives single pulse at the time of going input’s OFF condition  which is connected to it. Storage bit stores the status of input. Output bit stores the status of function performed by the block. PLC Program using OSR and OSF Ladder Logic Explanation RUNG 0000 Input 1 (I...

 To study the working of comparator blocks (EQU, NEQ, LES, GRT, LEQ and GEQ) using simple example in Allen Bradley programmable logic controllers (PLC). Ccomparator in PLC There are two parameter in each block, Source A & Source B –where values are stored. Description of Comparator Blocks : EQU :  Equal block is used to compare the two values stored in Source A and source B and gives output as “1” if both are equal and “0” if both are not equal. LES : Lesser than block is used to compare the two values stored in Source A and source B and gives output as “1” if  Source A value is Lesser than Source B value and “0” if Source A value is greater  than  or equal to Source B value. LEQ : Lesser than or equal to   block is used to compare the two values stored in Source A and source B and gives output as “1” if Source A value is lesser than or equal value to Source B value and “0” if Source A value is greater Source B value. NEQ : Not equal  block is...

 Write the PLC program for two tanks filling as per priority. Design the PLC Ladder Logic programming for this application. Tanks Filling as per Priority In pneumatic conveying system two or more tanks are used for material supply. Sometimes it is necessary to define priority for tanks. For example, if there are two feeding tanks are used in system and both the tanks are empty so we which tank should be filled first? So write priority logic in PLC for this problem. In this example we have taken two feeding tanks and we will fill tank as per priority. Hence we will fill tank 1 first if booth the tanks are detected empty. PLC I/O List of Inputs I1 :- Start PB I2 :- Stop PB I3 :- Tank 1 low level sensor (LL) I4 :- Tank 1 high level sensor (HL) I5 :- Tank 2 low level sensor (LL) I6 :- Tank 2 high level sensor (HL) List of Outputs Q1 :- Cycle ON Q2 :- Tank 1 feeding valve Q3 :- Tank 2 feeding valve List of Memory M1 :- Tank 1 feeding priority M2 :- Tank 2 feeding priority PLC Programmin...

 Jogging refers to repeated starting and stopping of a motor in short bursts to perform a particular movement such as moving a crane to a particular location. The motor is operated on full power. Jogging is moving the motor in small increments. Inching is similar to Jogging and the two are often confused with each other. Inching involves short thrusts of motion at reduced power. The motor is made to run at a reduced voltage. Jogging and Inching The definition of jogging or inching as described by NEMA is “the quickly repeated closure of a circuit to start a motor from rest for the purpose of accomplishing small movements of the driven machine.” The term jogging actually means to start a motor with short jabs of power at full voltage. The term inching means to start a motor with short jabs of power at reduced voltage. Although the two terms mean different things, they are often used interchangeably because both are accomplished by preventing the holding contacts from sealing the cir...

 Industrial Control Systems Different Types of Industrial Control Systems are Distributed Control System (DCS), Remote terminal unit (RTU) and Programmable logic controller (PLC). Distributed Control System (DCS) Plant distributed control system (DCS) – While the term DCS applies in general to any system in which controllers are distributed rather than centralized, in the power generation and petrochemical process industries it has come to refer to a specific type of control system able to execute complex analog process control algorithms at high speed, as well as provide routine monitoring, reporting and data logging functions. Figure : Simple example of distributed control systems In most applications, the input and output modules of the system are distributed throughout the facility, but the control processors themselves are centrally located in proximity to the control room. These systems typically use proprietary hardware, software and communication protocols, requiring that b...

 The recommended controller for SCADA systems is the programmable logic controller (PLC). PLCs are general-purpose microprocessor based controllers that provide logic, timing, counting, and analog control with network communications capability. Components of PLC A PLC consists of the required quantities of the following types of modules or cards, mounted on a common physical support and electrical interconnection structure known as a rack. A typical PLC rack configuration is shown in below figure. (1) Power supply : The power supply converts facility electrical distribution voltage, such as 230 VAC, 120 VAC or 125 VDC to signal level voltage used by the plc processor and other modules. (2) Processor : The processor module contains the microprocessor that performs control functions and computations, as well as the memory required to store the program. (3) Input/Output (I/O) : These modules provide the means of connecting the processor to the field devices. Examples of these modules ...

 Three levels of SCADA system architecture are recommended to support Industrial facilities. These vary in configuration to correspond to the size, criticality, and amount of mechanical and electrical equipment installed in the facility as noted. NOTE : The below shown figures are only example configurations which are used in previous decades. Here shown only for reference. Modern configurations are quite easy and simplified. SCADA and PLC Configuration Small PLC SCADA System The small system is recommended to support a remote data and/or telephone switch site. Such a facility would generally include a single service transformer and a single standby diesel generator. Some equipment inside would consist of a small rectifier for a 24 VDC bus, telemetry systems, PLC, HMI, cooling units Systems for these facilities may not achieve the reliability/availability criteria specified for larger facilities. The level of SCADA system redundancy should reflect the mechanical/electrical system r...

 In this article, we discuss about How to Convert Current to Voltage using Resistor with different examples like 0-20 mA to 0-10 VDC Conversion, 4-20 mA to 2-10 VDC Conversion, 0-20 mA to 0-5 VDC Conversion. Convert Current to Voltage It is extremely simple to measure 0-20 mA signal with a device that will measure only Voltage inputs. If the Voltage input module available will accept a 0-10 Vdc signal, but may not accept a 0-20ma signal directly. Basically, Ohms law is used to calculate a resistor value in order to convert the 0-20ma signal to a voltage. Example : 0-20 mA to 0-10 VDC Conversion Ohms law states: R = V/I where V is the Voltage, I is the current and R is the resistance R = 10V/0.020A = 500 Ohms V = I*R = 0*500 = 0V   V = I*R = 0.020*500 = 10V Example : 4-20 mA to 2-10 VDC Conversion Ohms law states: R = V/I where V is the Voltage, I is the current and R is the resistance  R = 10V/0.020A = 500 Ohms V = I*R = 0.004*500 = 2V V = I*R = 0.020*500 = 10V Example : ...

 In this article, we discuss about How to Convert Voltage to Current using Resistor with different examples like 0-10 VDC to 0-20 mA Conversion, 0-5 VDC to 0-20 mA Conversion. Convert Voltage to Current It is extremely simple to measure 0-10Vdc signal with a device that will measure only Current inputs. If Current input module available will accept a 0-20mA signal, but may not accept a 0-10Vdc signal directly. Basically, Ohms law is used to calculate a resistor value in order to convert the 0-10Vdc signal to a current. Example : 0-10 VDC to 0-20 mA Conversion Ohms law states: R = V/I where V is the Voltage, I is the current and R is the resistance  R = 10V/0.020A = 500 Ohms I= V/R = 0/500   = 0mA I= V/R = 10/500 = 0.02A = 20mA Example : 0-5 VDC to 0-20 mA Conversion Ohms law states: R = V/I where V is the Voltage, I is the current and R is the resistance  R = 5V/0.020A = 250 Ohms I= V/R = 0/250   = 0mA I= V/R = 5/250 = 0.02A = 20mA Note:- To avoid dama...

 To study the working of Up Counter PLC program in Allen Bradley Programmable Logic Controller (PLC). Up Counter In the above picture, there are totally three parameter, COUNTER: C4:0 – Counter File name (Timer C5:0, C5:1, C5:2…) PRESET –PRE: Limit value of COUNT-Up to how much it should count ACCUMULATOR –ACC: Running Value of counter when condition turn ON. From the data file, along with preset and accumulator, we have few more bits, CU: Count up Bit-whenever the counter is enable makes this bit to go ON. DN: Done Bit-When accumulator value reached preset value, done bit turns to ON. OV: Over Flow Bit-When accumulator value reached the limit value (32767),it rolls back to -32767 for the upcoming counter operation, Overflow bit turns ON, in this condition. Notes: UA-Update Accumulator Value-Only used when high speed counters are used in the program. CD & UN-Used for down Counter Function. Up Counter Description Using PLC Program I:0/0 is used to give input to counter and Prese...

 The pattern of bits in the mask determines which bits will be passed from the source address to the destination address, and which bits will be masked. Only bits in the mask that are set (1) will activate the mask operation. In this article, MVM (Masked Move) is discussed. Masked Move Instruction Block Diagram MVM Instruction Description There are three parameters in MVM, Source : It is the address of the data you wants to move. Mask : Address of the mask through which the instruction moves data. The mask acts like a filter    for the destination. Destination : It is the address where the instruction moves the data. There are three ways to give mask address, To enter a hexadecimal mask: type the hexadecimal value followed by the letter H (Hexadecimal). To enter a binary mask: type the binary value followed by the letter B (Binary). To enter a decimal mask: type the decimal value. Note : RSLogix will make any necessary conversion and display the hexadecimal value. MVM Ins...