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 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-E40SDR-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(S@) 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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