The Input/Outpout System – Discrete Devices

In the first module, you learned about the basic architecture and operation of the Allen-Bradley Micrologix 1000, including a brief introduction to its I/O system. This second module goes into more detail about the I/O system of the Micrologix 1000 Omron PLC. It includes four sections:

1. Types of input/output devices
2. Input interfaces
3. Output interfaces
4. System and I/O power distribution wiring

Types of Input/Output Devices

A MicroLogix 1000 PLC uses its input and output interfaces to connect with field input/output devices. To review, all input devices provide a signal to the PLC, and all output devices receive a signal from the PLC. All I/O devices, however, do not send and receive the same type of signal. There are two different types of I/O signals and two types of I/O devices that use them. The two types of I/O devices are discrete devices and analog devices.

At the end of this section, you will know:

• the difference between the two types of I/O devices
• which type works with the MicroLogix 1000

Discrete Devices

Discrete devices are input or output devices that provide or receive discrete digital signals. A discrete digital signal is one that can report only two states, such as ON/OFF or open/closed.

A limit switch is an example of a discrete input device because,1at any given time, it is either open or closed. It sends a discretePLdigital signal to a PLC. This signal can have one of only two values, 0 or 1, indicating that the device is either OFF or ON, respectively (see Figure 2-1).

A pilot light is an example of a discrete output device (see Figure 2-2). It can only be ON or OFF. A discrete output deviceOFFDiscrete0receives a discrete digital signal from a PLC telling it to be in either one state or the other. A discrete output can never be in a state in between ON and OFF.Figure 2-2. A pilot light receives a discrete signal from a PLC.

Next article we will continue introducing Analog Devices. The following products are some hot sale OMRON PLC on our store.

cp1e e20sdr a OMRON PLC, CP1E CPU AC 100-240V input, 24DI 16DO Relay, USB port, Original brand new

OMRON PLCCP1E series offers all functionality you need to control relatively simple applications, including outstanding positioning capability. All CP1E CPUs offer high-speed USB for quick programming. The “Easy Input Editor” software feature allows faster programming by using an intuitive ladder editor to create an organized application program. The CP1E series comes in two different types: CP1E-E is the most economical, while the CP1E-N has a built-in real-time clock, motion control capabilities, and a serial port to connect an HMI, barcode reader, or other serial device. Several optional units are available to increase the functionality. As the CP1E series shares the same architecture as the CP1L, CP1H, CJ, and CS series, programs are compatible for memory allocations and instructions.


★ New CP1E CPU Units now available.
-Lineup including CPU Units with built-in three ports: USB, RS-232C, RS-485.
-The depth of CPU Units with RS-232C connectors is reduced by 20 mm. (N30/40/60S(1))
★ Easy connection with computers using commercially available USB cables.
★ With E30/40/60(S), N30/40/60 or NA20 CPU Units, Add I/O, Analog I/O or Temperature Inputs by Connecting Expansion Units or Expansion I/O Units.
★ Input interrupts
★ Complete High-speed Counter Functionality.
★ Versatile pulse control for Transistor Output for N14/20/30/40/60 or NA20 CPU Units.
★ PWM Outputs for Transistor Output for N14/20/30/40/60([email protected]) or NA20 CPU Units.
★ Mounting Serial Option Boards or Ethernet Option Board to N30/40/60 or NA20 CPU Units.
★ Built-in analog I/O, two inputs and one output, for NA-type CPU Units.

CP1H-XA40DT-D PLC OMRON, CPU 24VDC, input 24 point transistor output 16 point Original brand new


Pulse output for 4 axes. Advanced power for high-precision positioning control
High-speed counters. Differential phases for 4 axes
Easily handles multi-axis control with a single unit
Eight interrupt inputs are built in. Faster processing of approximately 500 instructions speeds up the entire system
Serial communications. Two ports. Select option boards for either RS-232C or RS-485 communications
EtherNet communications, enabled by using an option board, two ports can be used as an EtherNet port to perform, EtherNet communications between the CP1H and a host computer
USB peripheral port
The structured text (ST) language, makes math operations even easier
LCD displays and settings, enabled using option board
Transistor output (sinking)

CJ1W-ID211 PLC OMRON I/O 16 input point 24VDC Original brand new


High-speed input models are available, meeting versatile applications.
ON Response Time: 15μs, OFF Response Time: 90μs
Use 24-VDC, 100-VAC, and 200-VAC models to connect to devices with different types of outputs.
The 24-VDC models can be connected to devices with either NPN or PNP outputs. There is no need to select the polarity. *1
A digital filter in the Unit can be set from 0 to 32 ms to reduce the influence of external noise.
Either a Fujitsu or MIL connector interface can be used. *2
Several models of Terminal Block Conversion Units are available, making it easy to connect to external devices.

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Inserting Parametric PLC Modules

A programmable logic controller (PLC) or programmable controller is a digital computer that is used to automatically regulate the industrial process. For example, comtrolling machinery on assembly lines of factor. This controller is designed to meet a range of industrial activities such as multiple inputs and output arrangements, extended temperature ranges, giving immunity to electrical noise, and providing resistance to vibration. The programs, designed to regulate the machine operation, are usually stored in a battery-backed or non-volatile memory. A PLC is an instance of a real time system becuase output results are needed to be produced in response to input conditions within a time-bound period; else, it will result in an unintended operation. Over the years, the functionality of PLC has evolvoed to accommodate sequential relay control, motion control, process control, distributed control systems, and networking. In PLC, microprocessor controlled interface is inbuilt and is designed to control or monitor some other I/O functions. Being an industrial computer control system, it always monitors the state of input devices and makes decisions on the basis of custom program for controlling the state of devices connected as outputs.


Inserting Parametric PLC Modules

AutoCAD Electrical can generate PLC I/O modules in different graphical styles through parametric generation technique on demand. These modules are generate by a database file and a library of symbol blocks. PLC I/O modules can be inserted as independent symbols. PLC modules behave like other schematic components. These modules are AutoCAD blocks containing attributes for connection points, tagging and so on.

The Insert PLC (Parametric) tool is used to insert a PLC module parametrically. To do so, choose the Insert PLC (PLarametric) button from the Insert Components panel of the Schematic tab; the PLC Parametric Selection dialog box will be displayed, as shown in Figure 10-1. Using this dialog box, you can select the PLC Module and its graphics that you want to insert in a drawing. The different options and areas in this dialog box are discussed next.

Manufacture Catalog Tree

The Manufacture Catalog tree, shown in Figure 10-2, displays a list of PLC modules. This list can be filtered by selecting the manufacturer, series, and type of PLC. The data displayed in the Manufacturer Catalog tree is stored in the ace_plc.mdb database file.

You can selet a PLC module from the Manufacturer Catalog tree. To do so, click on the + sign on the requried manfacturers module; PLC modules of the selected manafacturer will be displayed. Select the requried module from the module list; the detailed information of the selected module will be displayed at the lower part of the PLC Parametric Selection dialog box, as shown in Figure 10-3.

After specifying the required values in the I/O Point dialog box, choose the OK button from this dialog box; the I/O Address dialog box will be displayed, as shown in Figure 10-6. Using this dialog box, you can specify the address for the first I/O point. Fasttobuy offers different brands of PLC modules such as Siemens PLC, Omron PLC, Mitsubishi PLC, Delta PLC, SIEMENS PLC, Omron PLC, Fatek PLC, ect.

The values in the Quick picks drop-down list are based on the values that you have specified in the I/O Point dialog box in the Rack and SLOT edit boxes. Select the required value from the Quick picks drop-down list; the value will be displayed in the Beginning address edit box. Alternatively, enter a required value for the first I/0 address of a PLC module in the Beginning address edit box. Note that the other I/O points of a module will be incremented based on the value specified in the Beginning address edit box.

Choose the List button in the I/O Address dialog box; the Report Generator dialog box will be displayed. This dialog box display the information of the selected PLC module.

After specifying the required options in the I/O Address dialog box, choose the OK button in this dialog box; the selected PLC module will be inserted into the drawing.

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How to Select PLC for Motion Control

Almost every modern industry uses programmable logic controllers, commonly known as PLCs. These compact electronic devices enable much of the automation that is prevalent in today’s manufacturing processes. Delta PLC are utilized to get a myriad of purposes in company and business, such as every thing from climate manage systems to complex item assembly and packaging processes.

Buyers unfamiliar with PLCs and their benefits may feel overwhelmed as they begin the process of selecting and purchasing PLCs for their business or industry. This guide will offer a short overview from the history and function of PLCs, such as the programming specifications and a few important elements to help keep in thoughts whilst buying for PLCs.

The factors to consider when choosing a PLC:
Size of Memory
Compatibility to HMI

Format of PLC

You can go away using the format of Little PLC simply because the count of I/O is much less than one hundred and also you don’t have servos or analog to compete with; although, from a view of studying point and becoming that Medium Format of PLC Omron would be the business function horse you’ll make use of a Medium Format PLC having a genuine of back-plain.

Speed of PLC

The speed of PLC uses to be a main concern when planning controls but does not truly affect to controls now. Nowadays PLCs are rapid enough for the majority applications with full programs scan times usually less than 4 msec. This is the scan time needed for the PLC to seem at the service and program all the Inputs/Outputs. The Cycle Time is 4 seconds so the majorities PLCs today are glowing when think this requirement of time.

Size matters – Sizing a PLC is crucial towards the achievement of one’s project. As well little and also you might max out your I/O on modifications and additions. As well big and also you might blow your spending budget. Be sure you leave space for expansion but do not break the bank.

Count up your:

Discrete input points
Discrete output points
Analog input points
Analog output points

Communications. ALWAYS have a port available on the PLC to communicate with it from your laptop without disconnecting other devices.  With modern PLCs with multiple communications methods, there is no reason for this to happen.

Will you need remote I/O?  This can reduce installation time and troubleshooting in the long term.
Will you system utilize an HMI?  How will you communicate with it?
Will you have a way to remotely monitor it from either the office across the plant or across the country?  It is becoming a standard practice.  Personally I like Ethernet but there are many options.

Brand – I’ll be unpopular when I say this, but a PLC is a PLC when it comes to most capabilities.All of the major players such as Allen Bradley, Automation Direct, Mitsubishi,Omron, and Siemens have small, medium, and large scale PLCs. Always consider when brands the end user already is using. Things will always go smoother if the maintenance personel are already familiar with the brand of PLC you choose. Also try to choose a brand that will have good local  support for the end user if you are not in the area.


Whether buyers are looking for a replacement PLC for an existing system or are interested in automating a new process, they will likely be able to find PLCs that are appropriate for their needs on Fasttobuy. Fasttobuy’s user-friendly policies and search options allow buyers to enjoy a secure and profitable shopping experience. With their new PLCs, buyers will be able to implement time saving automation technologies for their business or industry.

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What are the advantages and disadvantages of PLC

What is PLC?
Programmable Logic Controller (PLC) is a digital computer used for the automation of various electro-mechanical processes in industries. These controllers are specially designed to survive in harsh situations and shielded from heat, cold, dust, and moisture etc. Delta PLC consists of a microprocessor which is programmed using the computer language.

The program is written on a computer and is downloaded to the PLC via cable. These loaded programs are stored in non – volatile memory of the PLC. During the transition of relay control panels to PLC, the hard wired relay logic was exchanged for the program fed by the user. A visual programming language known as the Ladder Logic was created to program the PLC.

The main difference from other computers is that PLC Omron are armored for severe conditions (dust, moisture, heat, cold, etc) and have the facility for extensive input/out put (I/O) arrangements.

Disadvantages of Programmable logic controller (PLC, programmable controller) control:

1. There’s too much work required in connecting wires.
2. There’s difficulty with changes or replacements.
3. It’s always difficult to find errors; And require skillful work force.
4. When a problem occurs, hold-up time is indefinite, usually long.

Advantages of Programmable logic controller (PLC) control:

1. Rugged and designed to withstand vibrations, temperature, humidity, and noise.
2. Have interfacing for inputs and outputs already inside the controller.
3. PLCs are easily programmed and have an easily understood programming language.

PLCs Applications


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