LG master k Training 1

EHA Training center

LG PLC training course Level I (beginner)

Electro Hydraulic Automation (EHA) ℡ (+202)4941760-499377 Fax.(+202)49192896 -2-

EHA Training center LG PLC training course Level 1 (beginners level) Pre-requisites Duration Description Technology

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Target audience

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contents

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None 6 days two hours per day Basics of PLC Operation and programming • LG K7M/MK-120S • PC • KGL and other appropriate Software All person that are required to deal with PLC circuits and PLC programming. Lesson 1: • Digital signal • Digital input device • Digital output device • PLC architecture "PLC inside view" • PLC circuit wiring and interface Lesson 2: • Ladder logic • Memory map • KGL programming software Lesson 3: • Timers 1. On delay timer 2. Off delay timer 3. Mono stable timer • Examples • using master controller tool Lesson 4: • Counters • Examples Lesson 5: • Step controller "sequence controller" and its' applications Lesson 6: • How to choose suitable PLC for your application • General notes


Course Philosophy: Training depends mainly on Practical applications. The course contents are spread out over a 6-day period one lesson per day every lesson is two hours, thus allowing absorption of technical data through practical example. Training manuals are supplied to the student for future reference. Included in the course is a copy of the entire PLC and HMI reference manuals in soft copy version. Once a student has completed the LG PLC course level I, he/she will be able to: • Create basic PLC programs. • Understand the internals of a PLC. • Have practical experience in choosing and connection and programming of PLC. • Be ready to advance to the LG PLC course level II.

Looking forward to having you on the course!


Lesson1

introduction to PLC

Main points Digital Signal Digital input Devices Digital output Devices PLC in side view Hardware wiring


1

Digital Signal Definitions of Digital Signal

An electrical signal that varies in discrete steps ON ( 24V or 5V TTL) And OFF (0V)

A digital signal is composed only of electrical pulses representing either zero or one

Digital value is non-sequentially changing value Written as the Number like 0,1,2,3. The signal of on or Off is written as digital Value of 0 or 1


1

Digital input devices Inputs come from sensors that translate physical phenomena into electrical signals. Typical examples of sensors are listed below in relative order of popularity. • Inductive proximity - is a metal object nearby? • Capacitive proximity - is a dielectric object nearby? • Optical presence - is an object breaking a light beam or reflecting light? • Mechanical contact - is an object touching a switch? Inputs for a PLC come in a few basic varieties, the simplest are AC and DC inputs. Sourcing and sinking inputs are also popular. Instead, the device only switches current on or off, like a simple switch. Sensors allow a PLC to detect the state of a process. Logical sensors can only detect a state that is either true or false.


2

Inductive Sensors Inductive sensors use currents induced by magnetic fields to detect nearby metal objects. The inductive sensor uses a coil (an inductor) to generate a high frequency magnetic field as shown in Figure.

If there is a metal object near the changing magnetic field, current will flow in the object. This resulting current flow sets up a new magnetic field that opposes the original magnetic field. The net effect is that it changes the inductance of the coil in the inductive sensor. By measuring the inductance the sensor can determine when a metal have been brought nearby. These sensors will detect any metals, when detecting multiple types of metal multiple sensors are often used. The sensors can detect objects a few centimeters away from the end. But, the direction to the object can be arbitrary as shown in Figure. The magnetic field of the unshielded sensor covers a larger volume around the head of the coil. By adding a shield (A metal jacket around the sides of the coil) the magnetic field becomes smaller, but also more directed. Shields will often be available for inductive sensors to improve their directionality and accuracy.


Example (CYLINDRICAL TYPE WITH LEADS) Part number: PR08DC Form autonics PR Series

FEATURES: Size: 8-12-18-30 mm diameter 2-wire DC, 3-wire DC or 2-wire AC models available Normally open or normally closed Shielded or non-shielded models 3-wire DC available NPN or PNP Standard or long body versions LED indication of output status 2 meter cable


Capacitive Sensors Capacitive sensors are able to detect most materials at distances up to a few centimeters. Recall the basic relationship for capacitance.

In the sensor the area of the plates and distance between them is fixed. But, the dielectric constant of the space around them will vary as different materials are brought near the sensor. An illustration of a capacitive sensor is shown in Figure. an oscillating field is used to determine the capacitance of the plates. When this changes beyond a selected sensitivity the sensor output is activated.

NOTE: For this sensor the proximity of any material near the electrodes will increase the capacitance. This will vary the magnitude of the oscillating signal and the detector will decide when this is great enough to determine proximity. These sensors work well for insulators (such as plastics) that tend to have high dielectric coefficients, thus increasing the capacitance. But, they also work well for metals because the conductive materials in the target appear as larger electrodes, thus increasing the capacitance as shown in Figure. In total the capacitance changes are normally in the order of pFard Electro Hydraulic Automation (EHA) ℡ (+202)4941760-499377 Fax.(+202)49192896 - 10 -

Dielectrics and Metals Increase the Capacitance

The sensors are normally made with rings (not plates) in the configuration shown in Figure. In the figure the two inner metal rings are the capacitor electrodes, but a third outer ring is added to compensate for variations. Without the compensator ring the sensor would be very sensitive to dirt, oil and other contaminants that might stick to the sensor. Example: (CYLINDRICAL TYPE WITH LEADS) Part number: CR18-8DN Form autonics CR Series

FEATURES: Size: 18mm or 30 mm 3-wire DC or 2-wire AC models normally open or normally closed 3-wire DC available NPN or PNP Adjustable sensitivity Detecting distance to 15mm LED indication of output status 2 meter cable IP66 (18mm) or IP65 (30mm)

Electro Hydraulic Automation (EHA) ℡ (+202)4941760-499377 Fax.(+202)49192896 - 11 -

Optical (Photoelectric) Sensors Light sensors have been used for almost a century - originally photocells were used for applications such as reading audio tracks on motion pictures. But modern optical sensors are much more sophisticated. Optical sensors require both a light source (emitter) and detector. Emitters will produce light beams in the visible and invisible spectrums using LEDs and laser diodes. Detectors are typically built with photodiodes or phototransistors. The emitter and detector are positioned so that an object will block or reflect a beam when present. A basic optical sensor is shown in Figure

In the figure the light beam is generated on the left, focused through a lens. At the detector side the beam is focused on the detector with a second lens. If the beam is broken the detector will indicate an object is present. The oscillating light wave is used so that the sensor can filter out normal light in the room. The light from the emitter is turned on and off at a set frequency. When the detector receives the light it checks to make sure that it is at the same frequency. If light is being received at the right frequency then the beam is not broken. The frequency of oscillation is in the KHz range, and too fast to be noticed. A side effect of the frequency method is that the sensors can be used with lower power at longer Distances.


Digital outputs devices

3

Digital outputs devices such that solenoids, valves

SOLENOIDS Solenoids are the most common actuator components. The basic principle of operation is there is a moving ferrous core (a piston) that will move inside wire coil as shown in Figure 5.1. Normally the piston is held outside the coil by a spring. When a voltage is applied to the coil and current flows, the coil builds up a magnetic field that attracts the piston and pulls it into the center of the coil. The piston can be used to supply a linear force. Well known applications of these include pneumatic values and car door openers.

VALVES The flow of fluids and air can be controlled with solenoid controlled valves. An example of a solenoid controlled valve is shown in Figure the solenoid is mounted on the side. When actuated it will drive the central spool left. The top of the valve body has two ports that will be connected to a device such as a hydraulic cylinder. The bottom of the valve body has a single pressure line in the center with two exhausts to the side. In the top drawing the power flows in through the center to the right hand cylinder port. The left hand cylinder port is allowed to exit through an exhaust port. In the bottom drawing the solenoid is in a new position and the pressure is now applied to the left hand port on the Top and the right hand port can exhaust. The symbols to the left of the figure show the schematic equivalent of the actual valve positions. Valves are also available that allow the valves to be blocked when unused.



PLC in side view

3

The PLC mainly consists of a CPU, memory areas, and appropriate circuits to receive input/output data. We can actually consider the PLC to be a box full of hundreds or thousands of separate relays, counters, timers and data storage locations. Do these counters, timers, etc. really exist? No, they don't "physically" exist but rather they are simulated and can be considered software counters, timers, etc. These internal relays are simulated through bit locations in registers. (More on that later)

What does each part do? CPU - Central Processing Unit is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime these were 8-bit microcontrollers such as 8051, and now these are 16- and 32-bit microcontrollers. INPUT RELAYS-(contacts) these are connected to the outside world. They physically exist and receive signals from switches, sensors, etc. Typically they are not relays but rather they may be transistors or opti-couplers. Marker RELAYS -these do not receive signals from the outside world nor do they physically exist. They are simulated relays and are what enables a PLC to eliminate external relays. There are also some special relays that are dedicated to performing only one task. Some are always on while some are always off. Some are on only once during power-on and are typically used for initializing data that was stored. COUNTERS-These again do not physically exist. They are simulated counters and they can be programmed to count pulses. Typically these counters can count up, down or both up and down. Since they are simulated they are limited in their counting speed. There are also high-speed counters that are hardware based. We can think of these as physically existing. Most times these counters can count up, down or up and down. Electro Hydraulic Automation (EHA) ℡ (+202)4941760-499377 Fax.(+202)49192896 - 15 -

TIMERS-These also do not physically exist. They come in many varieties and increments. The most common type is an on-delay type and off-delay. Increments vary from 1ms through 1s. OUTPUT RELAYS-(coils) these are connected to the outside world. They physically exist and send on/off signals to solenoids, lights, etc. They can be transistors, relays, or triacs depending upon the model chosen. DATA STORAGE-Typically there are registers assigned to simply store data. They are usually used as temporary storage for math or data manipulation. They can also typically be used to store data when power is removed from the PLC. Upon power-up they will still have the same contents as before power was removed. Very convenient and necessary!!


PLC SCAN CYCLE A PLC works by continually scanning a program. We can think of this scan cycle as consisting of 3 important steps. There are typically more than 3 but we can focus on the important parts and not worry about the others. Typically the others are checking the system and updating the current internal counter and timer values.

Step 1-CHECK INPUT STATUS

First the PLC takes a look at each input to determine if it is on or off. In other words, is the sensor connected to the first input on? How about the second input? How about the third... It records this data into its memory to be used during the next step. Step 2-EXECUTE PROGRAM

Next the PLC executes your program one instruction at a time. Maybe your program said that if the first input was on then it should turn on the first output. Since it already knows which inputs are on/off from the previous step it will be able to decide whether the first output should be turned on based on the state of the first input. It will store the execution results for use later during the next step. Step 3-UPDATE OUTPUT STATUS

Finally the PLC updates the status of the outputs. It updates the outputs based on which inputs were on during the first step and the results of executing your program during the second step. Based on the example in step 2 it would now turn on the first output because the first input was on and your program said to turn on the first output when this condition is true. After the third step the PLC goes back to step one and repeats the steps continuously. One scan time is defined as the time it takes to execute the 3 steps listed above.


Memo ……………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… …………………………………………………………………………….…………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… Electro Hydraulic Automation (EHA) ℡ (+202)4941760-499377 Fax.(+202)49192896 - 18 -

Hardware wiring

1.5

Input wiring Dc 24v

Output wiring



Wiring precautions: • Re-check the input voltage for the input part. If a voltage over the maximum switching capacity (24V) is applied, it can cause faults, destruction or fire. • Before applying the power to part that has polarities, be sure to check its polarities. • During drilling or wiring, do not allow any wire scraps to enter the PLC. It can cause malfunction and fault. • Wiring I/O wires with high voltage cable or power supply line can cause malfunction or disorder. • Be sure that any wire does not pass across during input LED (I/O status will not be clearly identified). • If an inductive load has been connected to output part, connect parallel surge killer or diode to a load. Connect the cathode of diode to the ‘+’ part of the power supply.

• Be cautious that strong shock does not applied to the I/O part. • Do not separate the PCB from its case.


Memo ……………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… …………………………………………………………………………….…………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… Electro Hydraulic Automation (EHA) ℡ (+202)4941760-499377 Fax.(+202)49192896 - 22 -

2

Lesson 2

Main points Ladder Logic Memory Map KGL Programming Software


2.1

Ladder Logic

Ladder logic is the main programming method used for PLCs. Relay is a simple device that uses a magnetic field to control a switch, when a voltage is applied to the input coil; the resulting current creates a magnetic field the magnetic field pulls a metal switch (or reed) towards it and the contacts touch, closing the switch. The contact that closes when the coil is energized is called normally open. The normally closed contacts touch when the input coil is not energized. Relays are normally drawn in schematic form using a circle to represent the input coil.

Example1: Now let's compare a simple ladder diagram with its real world external physically connected relay circuit and see the differences.

Figure (1.6)

In the above circuit, the coil will be energized when there is a closed loop between the + and - terminals of the battery. We can simulate this same circuit with a ladder diagram. Aladder diagram consists of individual rungs just like on a real ladder. Each rung must contain one or more inputs and one or more outputs. The first instruction on a rung must always be an input instruction and the last instruction on a rung should always be an output (or its equivalent).


Example 3: MOTOR START WITH LATCH Make a program to control motor through push button but motor not stop after releasing the button but can stop by pushing push button (P1)

P0 COM K

24VDC P1 P40 K

COM 24VDC M

220VAC


[[[[[[[[[[[[[[[

memory mapping

2.2

To study PLC you must know the memory mapping of the data memory of this PLC, the PLC data memory is divided into several parts , every part have a name & special specifications , these parts called devices . MK 120S DATA MEMORY DEVIDED INTO

1- P area 2- M area 3- K area

1- P Æ input &output image. This device for real input and real outputs only, you can change these device status (write in these bits) using hardware, if you put 24v on p0 input, and the bit of p0 get high (on)

Example:

P0 Æ input for point labeled 0 on plc. P40 Æ output for point labeled 40 on plc. Note: No. of points (pxx) limited to plc 2- M Æ auxiliary relay. (Markers) This device for not real input and not real outputs, you can only write in these bits using software instructions.

Example:

M0 Æ internal imagine input or output in plc.

Note: No. of points (mxx) limited to plc software point For example for master k120s from m000 to m191f (191*16= 3056 marker)


3- K Æ keep relay This device the same like m device but it can keep its value even if power off and on again.

Example: K0 Æinternal imagine input or output in plc can Keep its value even power off and on again.

Note: No. of points (kxx) limited to plc software point For example for master k120s from k00 to k31f (31*16= 496) Keep relay. (I.e. if power off while k0 was on, when power turn on again we Will find k0 on)

4- F Æ special relay. (Flags) These special relays (flags) are predetermined flags each one make one predetermined job only can’t be changed

Example: F10 Æalways no flag. F11 Æalways off flag. Note: You can get list of flags by click f3 from the keyboard then select flags


Programming software

2.3

The programming software of LG Master K PLC's is named KGLWIN, KGLWIN is under windows package which you can use to write ladder or mnemonic (statement) programs and to download it to PLC also to emulate the downloaded




You can open an existing files b KGL win





Lesson3

3

Main points Timers Examples Using Master controller tool


Timers

3.1

The most popular types of timers

1 –TON

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ON DELAY TIMER

2 –TOFF

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OFF DELAY TIMER

3 –TMON

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MONOSTABLE TIMER

Let's now see how a timer works. What is a timer? It's exactly what the word says…….. It is an instruction that waits a set amount of time before doing something. Sounds simple doesn't it.

On-Delay timer This type of timer simply "delays turning on". In other words, after our sensor (input) turns on we wait x seconds before activating a solenoid valve (output). This is the most common timer. It is often called TON (timer on delay)

Off-Delay timer This type of timer is the opposite of the on-delay timer listed above. This timer simply "delays turning off". After our sensor (input) sees a target we turn on a solenoid (output). When the sensor no longer sees the target we hold the solenoid on for xseconds before turning it off. It is called a TOFF (timer off-delay) and is less common than the on-delay type listed above. (i.e. few manufacturers include this type of timer) Let's now see how to use them. We typically need to know 2 things: 1. What will enable the timer? Typically this is one of the inputs.(a sensor connected to input P0000 for example) 2. How long we want to delay before we react. Let's wait 5 seconds before we turn on a solenoid, for example. When the instructions before the timer symbol are true the timer starts "ticking". When the time elapses the timer will automatically close its contacts. When the program is running on the plc the program typically displays the elapsed or "accumulated" time for us so we can see the current value. Typically timers can tick from 0 to 65535 times.


Why this specified numbers? Again it's because LG MK PLCs have 16-bit timers. We'll get into what this means in a later chapter but for now suffice it to say that 65535 is 16-bit binary. Each tick of the clock is equal to x-seconds. Typically LG MK series offers several different ticks. 10 and 100 ms increments (ticks of the clock). An "ms" is a milli-second or 1/1000th of a second. MK 120s also offer 1ms increments. These different increment timers work the same as above but sometimes they have different names to show their time base. Shown below is a typical timer instruction symbol we will encounter and how to use it.

This timer is the on-delay type and is named T0. When the enable input is on the timer starts to tick. When it ticks 10 (the preset value) times, it will turn on its contacts that we will use later in the program. Remember that the duration of a tick (increment) varies with the time base used. (I.e. in MK 120s I can set some timers the time base 100msec, others to the time base 10msec ...)

In this diagram we wait for input P0 to turn on. When it does, timer T000 (a100ms increment timer) starts ticking. It will tick 100 times. Each tick (increment) is 100ms so the timer will be a 10000ms (i.e. 10 second) timer. 100ticks X 100ms = 10,000ms. When 10 seconds have elapsed, the T000 contacts close and P40 turns on. When input P0 turns off (false) the timer T000 will reset back to 0 causing its contacts to turn off (become false) thereby making output P40 turn back off. To get help on timers just click F10 (dialogue box will appear) Î then SELECT TON FROM the LIST Î THEN CLICK help


To put timer in the ladder diagram click F10 from the keypad, dialogue box will appear then write the following expression

Instruction

op1 op2

Where: Op1 is the timer number, in MK120s there are 256 timer from T0 to T255 Op2 is the delay time multiplied by 0.1 sec (To make 10 sec delay then make op2=100) Example To put on delay timer with 100sec delay do the following Click F10---write Ton Tn 1000 as n any number from 0-255 Hint: Don’t use the same timer more than one Hint: Every timer has a bit or contact take the same name of the timer for example t10 is contact of the timer T10 this bit condition depend on its timer condition.


Examples

3.2

1-TON Example


Example: Lamp flickers


2-TOFF example: Write a program to operate a lamp for 20 sec if I hit a button. Solution connect the button with P0 and connect the lamp with P40, the program are as following

When push the button P0 get on the contact T0 get on, when release the button P0 get off T0 will keep on for 20 sec then get off


3- Monostable Timer example:



Extra

Examples

Example1: Motor with two direction with time OBJECT: Make a program to control motor with two directions with two DEFFERINT TIME. SOLUTION: When start p.b (P0) pushed motor run in forward direction so Till certain time (T144) then motor stop running at forward direction (P40 off ) and reverse direction Begin till certain time (T145) then motor stop running at backward direction (P41 off ) and run forward again and so on.


Example 2 When click start pushbutton we want the conveyer to run with the sequence C---10sec delay—B—20sec delay ---A when I click stop I want the conveyer to stop with the sequence C—10sec delay—b-10 sec delay


Master Control

3.3

Let's now look at what are called master controls. Master controls can be thought of as "emergency stop switches". An emergency stop switch typically is a big red button on a machine that will shut it off in cases of emergency. Next time you're at the local gas station look near the door on the outside to see an example of an e-stop.

Note: We're not implying that this instruction is a substitute for a "hard wired" e-stop switch. There is no substitute for such a switch! Rather it's just an easy way to get to understand them. The master control instruction typically is used in pairs with a master control clear (reset). Abbreviated as MCS/MCSCLR (master control/master control reset),

Here is the master control symbol looks.

Below is an example of a master control clear.

MCS & EXAMPLE






Lesson4

4

Main points Counters Examples Using Positive edge and negative tool


Counters

4.1

There are four types of counters:-

1- CTR 2- CTU 3- CTD 4- CTUD

Æ Æ Æ Æ

RING COUNTER UP COUNTER. DOWN COUNT UP DOWN COUNTER

A counter is a simple device intended to do one simple thing count. There are up-counters (they only count up 1, 2, 3...). These are called CTU (count up), there are down counters (they only count down 9, 8, 7...). These are typically called CTD (count down) when they are a separate instruction. there are also up-down counters(they count up and/or down 1,2,3,4,3,2,3,4,5,...) these are typically called CTUD (up-down counter) when they are separate instructions.

To get help on counters Just click F10 (dialogue box will appear) Î then write CTU Î help To put counter in the ladder diagram, click F10 from keypad dialogue box will appear write in it the following expression CTU C0 10 ASCTU the counter type may be CTU or CTD or CTUD or CTR every type is explained in details in the following pages C0 the counter number, there are 256 counter in mk120s plc, from C0 to C255, I can use every counter only once the set point of the counter, it can from 0 to 65535

Hint: every counter have a bit or a contact, these bit state change depending on the state of it's counter for example if the counter is CTU then it's bit will have 0 as the present value in the counter less than the set point, when the present value in the counter is more than or equal the set point the bit of this counter will be 1

Hint: The bit of any counter take the same number of these counters, as c100 is the bit of the counter c100


CTU+EXAMPLE


CTD+EXAMPLE


CTUD+EXAMPLE



CTR+EXAMPLE


MAKE A WATCH Make a program to make out contact after 1 month Solution: make counter (C1) with enable F93 ( this is special clock flag for 1 sec ) C1 preset value is 60 his counter express seconds , so after1 minute (60 second) C1 make pulse to C2 (minute counter) and C2 after 60 minute (Pulse) give pulse to C3 ( hour counter) and when hour counter reach 24 Hour (pulse) give C4 (month counter).


3- STORE EXAMPLE OBJECT: Store with maximum capacity 200 car, has two gates each one has sensor make a program to output signal when store empty and other one when full Solution: By up down counter, up enable (P0) from entrance gate and down enable from exit Gate and compare counter value if less than 1 out EMPTY signal (P40) and if Greater Than 200 out FULL signal (P41)


D & D NOT INSTRUCTIONS

4.2

A one-shot (D& DNOT) is an interesting and invaluable programming tool. At first glance it might be difficult to figure out why such an instruction is needed. After we understand what this instruction does and how to use it, however, the necessity will become clear. A one-shot is used to make something happen for ONLY 1 SCAN. (You do remember what a scan is, right??) . The name of the instruction is D / D NOT (differentiate up/down).

D Instruction, device may be any P,M,K,L device

Above is the symbol for a D (differentiate) instruction. A D NOT instruction looks the same but inside the symbol it says "D NOT", Lets now setup an application to see how this instruction actually functions in a ladder. This instruction is most often used with some of the advanced instructions where we do some things that MUST happen only once. However, since we haven't gotten that far yet, let's set up a flip/flop circuit. In simple terms, a flip/flop turns something around each time an action happens. Here we'll use a single pushbutton switch. The first time the operator pushes it we want an output to turn on. It will remain "latched" on until the next time the operator pushes the button. When he does, the output turns off.

Here's the ladder diagram that does just that: Now this looks confusing! Actually it's not if we take it one step at a time.


• •

•

Rung 1-When NO (normally open) input P0000 becomes true D M10 becomes true. Rung 2- NO M10 is true, NO M15 remains false, NC M15 remains true, and NC M10 turns false. Since we have a true path, (NO M10 & NC M15) OUT M15 becomes true. Rung 3- NO M15 is true therefore OUT P40 turns true. Next Scan

•

•

•

Rung 1- NO P0 remains true. M10 now becomes false. This is because the D instruction is only true for one scan. (i.e. the rising edge of the logic before it on the rung) Rung 2- NO M10 is false, NO M15 remains true, NC M15 false, NC M10 turns true. Since we STILL have a true path, (NO M15 & NC M10) OUT M15 remains true. Rung 3- NO M15 is true therefore OUT P40 remains true.

After 100 scans, NO P0 turns off (becomes false, user release the push button connected P0). The logic remains in the same state as "next scan" shown above. (D doesn't react therefore the logic stays the same on rungs 2 and 3) On scan 101 NO P0 turns back on. (Becomes true, user re push the button) • •

•

Rung 1-When NO (normally open) input P0 becomes true D M10 becomes true. Rung 2- NO M10 is true, NO M15 remains true, NC M15 becomes false, and NC M10 also becomes false. Since we no longer have a true path, OUT 1001 becomes false. Rung 3- NO 1001 is false therefore OUT 500 becomes false

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D mean differentiate , this instruction write 1 in the bit it applied on for 1 scan cycle when the devices before it translate from disconnect to connect state Electro Hydraulic Automation (EHA) ℡ (+202)4941760-499377 Fax.(+202)49192896 - 61 -

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D NOT , this instruction write 1 in the bit it applied on for 1 scan cycle , when the devices before it translate from connect to disconnect state

When P0 get on m10 get on for one scan cycle, when P0 get off m12 get on for one scan cycle


EXAMPLE: OBJECT: Great knife driven by motor, make a program to operate this knife through selector and when Overload occur knife sops and never run again before make the selector off and ON again Solution: As it requested the run command hanged on the rising edge of the SELECTOR So we have to take the rising edge of the SELECTOR by D command on marker (m10 for example) And use this marker for run the motor (P40) and when overload point come (P1) motor stop and will not work till p1 return to its initial position and the next rising edge come again by changing the SELECTOR from ON to off and make it ON again



5

Lesson5

Main points STEP CONTROLLER


Step controllers like no. of ladders each one contain of no. of stairs Only one stair (step) can be on and all stairs for this ladder are off.

For example: For ladder S00.00 (it varies from S00.00 to S00.99) Step S00.00 ON firstly and if any step come (like S00.07) S00.00 OFF.

There are two ways to use the step controller

Last in priority (sequence command) OUT Sxx.xx

Step controller SET xx.xx

LAST IN PRIORITY OUT Sxx.xx For this method we can move from any step to the other one without any condition, but we must remember that only one step will be ON


SEQUENCE COMMAND SET Sxx.xx

In this method I can only move from step to the next step (the next only) by SET order, and there are two conditions 1- The previous step was ON before trying to SET this step (for example to SET S00.02 S00.01 must be ON first) 2- Use SET order Notes: Only the first step (for example S00.00 for ladder S00) can come at any time (i.e. If we SET S00.00 for ladder S00 at any time S00.00 will be ON)



Example:

This program shows briefly an example of sequential control by using SET Sxx.xx instruction. In this Example, there are 4 processes and each process is performed in sequence. The process 2 starts after the process 1 ended, and process 3 starts after the process 2 finished. When the process 4 is completed, the process 1 will start again.



Lesson6

6

Main points

How to choose suitable PLC for your application General notes


How to choose suitable PLC for your application 1-determine number of digital inputs and digital outputs 2-if there are analog inputs or analogue outputs Determine them number 3-if there are any other special inputs (Like RTD, Thermocouple and high speed pulses (encoder)...etc) Determine its number after determine these data you can found more than plc type match with these data , you will found that mk10s1 the most cheapest type , after that mk80S ,after that mk120s, after that mk200s , after that mk300s

*there are no Thermocouple expansion modules in MK120S *there are no RTD expansion modules in MK200S * For digital inputs and digital outputs it is preferable to take plc Have inputs outputs 120% of required inputs outputs *for MK 200s, mk300s it is preferable to take baseboard have Two slots more the required number of slots



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