 Hello everyone. Welcome to this session on PLC programming. Let us today learn one of the programming method of PLC instruction list. So at the end of this session you will be able to examine basic instructions or operators which are used in instruction list programming method. Also you can able to write small instruction list programs for basic logic operations. So we have gone through all the programming methods which are supported by standard IEC 61131 part 3. So ladder diagrams, functional block diagram programming, instruction lists, sequential function charts, structure text. So in this session we are going to learn instruction list for basic operations. So let us learn about instruction list programming method. So it is a low level textual language in which programs are written as a series of instructions. So if you observe here one example is shown. So this instruction or operation is mentioned with a label then operator, operand and command. So if you observe this statement it very much similar to assembly language programming instruction. So it is very much similar like language also sometimes referred as a memonic programming code. So this instruction start with some label which is optional then the operation which you want to perform then operands and again optional commands. So each instruction shall begin on a new line. So this is the condition. Then each instruction shall contain an operator with an optional modifier and if necessary for particular application one or more operands separated by commands. So let us go through this example where one run each shown for a ladder diagram having one output and one input switch. So if you want to write a instruction list program for this particular ladder example you will see that here LD in 0 is the first instruction which loads the status of switch A into the memory. Then next instruction is store st out 0. So this instruction reads the status of switch and it outputs to the light. So this is very simple example having only one run. Let us go through some instruction code memonics. So here some examples are shown which are defined in IEC standard. Then some of the companies also uses these instructions but with their own conventions. So LD which loads the operand into the result register. So if you compare this with a ladder diagram so it is nothing but a start run start run with open contact. So Mitsubishi uses the same convention. Omeran also uses same convention whereas Siemens use A to load this operand into the result register. Second is the load negative LDN. Mitsubishi have LDI. Omeran have LD0 whereas Siemens uses AN convention. So the meaning of this LDN operator is load the negative operand into the result register. So it is very much similar to a start a run with closed contact. Then we have some logical operators also and negative or negative. Then again we have a store which is used for writing to an output. So these are few examples of operators. You can also have addition, subtraction, multiplication, division operators also. Please go through the standard IEC 1131 part 3 for further details. So let us write an instruction list program to turn output A on when input A is satisfactory and turn output B on when input A is not satisfactory. So if you observe this statement we have only one input condition whereas we have two outputs to turn on. So let us write an instruction list and corresponding ladder diagram for this example. So here for first run we have two instructions LDX400STY430. So these statements are responsible for first run whereas LDNX400 and STY431 are responsible for second run. So LDX400 reads the status of input A and STY430 applies the status of X400 to output A. Then LDNX400 reads the status of input A but in negative form and STY431 applies this status to output B. So this is a simple example which shows you how to write an instruction list for a particular ladder diagram or for particular example. Let us go to the next example. Let us develop an instruction list program for the given ladder diagram. So here two switches input A and B and input B are connected in series. Similarly input C and input D is also connected in series whereas these two are connected in parallel. So here you have one block and another block. So first block is made up of input A and input B whereas second block is made up of input C and input D. And if you observe this is a combination of ending and oring and output is responding to this combination. So here is the equivalent instruction list program for this ladder diagram. So first read the status of X400 then AND it with the status of X401 switch. So this is similar to writing instructions for a micro controller. Then for second block LDX402 reads the status of input C then ANDX403 and the status of input D2 input C. Then these two blocks are all together using OR instruction and at last store the status to the output Y430. So here this first AND instruction ANDs the status of two switches 400 and 401 whereas second AND instruction ANDs the status of two switches X402 and X403 then OR instruction is used to OR the two blocks and at last store instruction is used to write the status, overall status to output Y430. Let us solve one more example. A lamp is required to be switched on if outputs of a pump sensor and pressure sensors are satisfactory or if the output of a test switch is satisfactory. So let us develop an instruction list program for this given task. So if you read this statement we can write a expression lamp is equal to pump AND it with pressure OR with test switch. So we have just converted this problem statement into a Boolean expression with the ANDing and ORing operations. So this is how a ladder diagram and corresponding instruction list code looks like. So two switches in series and third two sensors are in series and a switch is in parallel with them and a lamp at the output side. So this first load instruction LD reads the status of pump sensor then AND instruction ANDs the status of pressure sensor with pump sensor then again loading instruction reads the status of test switch and then ORB instruction is used to add these two blocks together and last store ST instruction is used to write the status to output Y430 that is a lamp. So this are few examples where we have used some basic operations to develop simple instruction list programs for simple logic operations. These are the references you can read further. Thank you.