What is the definition of "binary coded decimal"?
A binary number system in which each decimal digit from 0 to 9 is represented by four binary digits (bits). The four positions have a weighted value of 1, 2, 4, and 8, ranging from right to left.

## PLCs Training

Class Information
 Tooling U-SME classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and will take approximately one hour to complete.
 Class Name: PLC Inputs and Outputs 240 Description: This class covers different types, configurations, capacities, and current conversions for PLC I/Os. Includes an Interactive Lab. Difficulty: Intermediate Number of Lessons: 14 Language: English, Spanish

Class Outline
• Objectives
• The PLC Input/Output Section
• I/O Screw Terminals
• I/O Configuration
• I/O Power Conversion
• Discrete I/Os
• Data I/Os
• Sinking I/Os
• Sourcing I/Os
• Noise Filtering and Surge Suppression
• Troubleshooting the Input/Output Module
• Troubleshooting I/O Devices
• Forcing and Disabling I/Os
• Summary

Class Objectives
• Describe the PLC input/output section.
• Explain the function of I/O screw terminals on a PLC I/O module.
• Distinguish between fixed I/O and expandable I/O configurations.
• Explain how I/O power conversion works.
• Describe discrete I/Os.
• Describe data I/Os.
• Describe sinking I/Os on a DC circuit.
• Describe sourcing I/Os on a DC circuit.
• Describe noise filtering and surge suppression.
• Explain how to troubleshoot an I/O module.
• Explain how to troubleshoot I/O devices.
• Explain how to use the force command and the disable command.

Class Vocabulary

Vocabulary TermDefinition
The unique location assigned to each I/O module so that it may be correctly referenced and signaled by the PLC program.
A continuously variable signal. Analog signals differ from digital signals in that small fluctuations in the analog signal are meaningful.
A device that changes the continuous fluctuations in voltage from an analog device into a digital signal.
The area on the back of a PLC enclosure where various logic and control elements are interconnected. The backplane is usually a printed circuit board that is connected to other printed circuit boards.
A number system used for PLCs that has either 0 or 1 as a value. Using binary, a function is either on or off.
A binary number system in which each decimal digit from 0 to 9 is represented by four binary digits (bits). The four positions have a weighted value of 1, 2, 4, and 8, ranging from right to left.
A configuration of semiconductor devices that changes AC to full-wave pulsating DC.
The input/output of an analog module. Channels can be single ended or differential pairs.
The frame or enclosure of a modular PLC.
The screw terminal on a PLC that connects to the power source.
The internal electronic process in a PLC that converts AC to DC, and DC to AC.
A PLC input/output that processes many different types of signals over a wide range.
To test a PLC for errors.
A numbering system that uses ten digits, from 0 to 9, arranged in a series of columns to represent all numerical quantities. Each column or place value has a weighted value of 1, 10, 100, 1000, and so on, ranging from right to left.
A type of analog channel in which each input has a connection to its own input terminal and corresponding terminal.
Consisting of information that is input or output electronically as a series of pulses or signals often resulting in binary strings of 0s and 1s.
A device that can measure voltage, current, or resistance. A digital multimeter is the most versatile and common meter used today for electrical maintenance.
A device for converting digital signals into continuous analog signals. The converter usually buffers the input so that the output remains the same until the input changes. A typical converter provides two analog output channels ranging from 0 to +10 volts with eight bits per channel resolution; also provides two logic level outputs for external device control.
A command used to prevent an output device from operating. Disable is the opposite of the force command, and it can be used to prevent the operation of one or all of the output devices.
A signal that has two states, ON and OFF.
An input/output device or module that recognizes only binary on/off signals. A pushbutton is an example of a discrete input device, and a light is an example of a discrete output device.
An AC power line disturbance caused by sudden changes in the load. Electrical noise is problematic to solid state devices because they cannot differentiate between an intended electrical pulse and an unintended electrical spike.
An input/output section that can be expanded to allow more inputs and outputs.
An I/O unit that is separate from the controller of the PLC.
A peripheral device that provides input to or sends output from a PLC.
I/Os located onboard the PLC in a unit that also contains the processor, input/output modules, and power supply. With fixed I/Os, you cannot add more inputs or outputs than the number that have already been allotted.
A troubleshooting command used to override the input/output status of an application in order to test or debug a PLC program. The force command overrides any safety features in the PLC program.
An indicator lamp on a PLC that confirms inputs and outputs are in forced operating mode.
The section of an expandable PLC to which input and output devices are connected.
The section of a PLC to which input and output devices are connected. The I/O section also converts power levels.
An AC electrical load in which the voltage wave reaches its peak before the current.
A device, usually a type of sensor, that sends information into a PLC. Inputs are connected to the PLC by input relays.
The jack used to physically connect an input device to a PLC. The input relays transfer signals to the internal relays.
The section of a PLC to which input and output devices are connected. The input/output section also converts power levels.
An I/O that is in the same rack as the processor.
A type of wiring that allows multiple signals to be processed through a single channel. Multiplexing is used to save on wiring and I/O ports.
A device that performs a mechanical action after receiving the electrical signal to do so from the PLC output relays.
The jack used to physically connect an output device to a PLC. The output modules transfer signals from the internal relays.
A layered construction of material used to mechanically support and electrically connect electronic components using conductive pathways, or traces, etched from copper sheets laminated onto a non-conductive surface.
An operational mode of the CPU of a PLC that is used for monitoring and changing the PLC program.
A device, usually a personal computer, used to enter instructions into the PLC. Some programming devices are small enough to fit in your hand.
An enclosure with slots in it that is to connect multiple parts of a PLC.
An Input/output module that is located far away from the CPU of the PLC.
Cable that has an outer layer of insulation covering an innerlayer of conducting material. Shielded cable is used to reduce electronic noise and voltage spikes.
A type of analog channel in which all the input commons are tied together.
An I/O module with circuitry that allows current to flow in either direction.
A type of circuit in which the I/O device provides current to the I/O module.
An electrical circuit used to suppress electrical spikes. Snubbers are often used with inductive loads.
A type of circuit in which the I/O module provides current to the I/O device.
A light-emitting diodes on a PLC that provides information on the operating condition of PLC I/Os.
A device that joins wires or cables. Terminal blocks typically snap into a metal rail or are screw mounted on the panel of a control enclosure.
An operational mode of the CPU of a PLC that checks if inputs and outputs are working without actually energizing the input/output circuits or devices.
A testing device that vibrates when a current is detected. Also called a "wiggy", it is small and durable, but may be replaced by more versatile and safer DMMs.
A sudden, short surge in voltage. Voltage spikes can be caused by lightning, power outages, short circuits, or power transitions in large equipment on the same power line.