PLC-Mechatronics-Pe-4030-Dec-21

General Objectives To explain and understand the following PLC Programmable logic controller; Structure of PLC and system components; Programming Languages; ( LAD,STL,FBD) Logic Gates application for PLC Timers Counter Shift Register Jump Programming Applications 12/22/16 prof CHARLTON S INAO concept: 12/22/16 prof CHARLTON S INAO 12/22/16 prof CHARLTON S INAO 12/22/16 prof CHARLTON S INAO 12/22/16 prof CHARLTON S INAO Programmable Logic Controllers • Defined by NEMA as a digital electronic apparatus with a programmable memory for storing instructions to implement specific functions (logic, sequencing, timing, counting, and arithmetic) to control machines and processes • Considered as the first industrial-based computer 12/22/16 prof CHARLTON S INAO 12/22/16 prof CHARLTON S INAO 12/22/16 prof CHARLTON S INAO 12/22/16 prof CHARLTON S INAO 12/22/16 prof CHARLTON S INAO 10 Advanced Capabilities PLCs are often used in applications that go beyond basic logic solving Some advanced programming and input/output (I/O) functions are listed below Calculations—The ability to basic scientific calculations Lower end PLCs only use integer math, while higher end PLCs also provide floating point math Analog I/O—Continuous voltage and current values can be input and output Feedback control—Proportional integral derivative (PID) controller calculations are provided as function blocks and can be used with analog I/O Communications—The ability to transmit data as strings over serial ports or to transfer parts of the PLC memory using proprietary protocols ASCII strings—Functions to manipulate ASCII strings System— Fault detection, status monitoring, interrupt routines, etc Fuzzy logic—Some PLCs include fuzzy set functions for nonlinear control problems 12/22/16 prof CHARLTON S INAO 138 At a minimum PLCs use communications for programming But in many applications PLCs are used to communicate with other devices In the past, most communications were based on proprietary, or closed, standards More recently a few open communication standards have been developed and are supported by many vendors; these include Profibus, DeviceNet, CanBus, and ModBus There has also been a trend to use more universal communication standards such as RS-232, RS-422, RS-485, and Ethernet An example of an automation system is shown in Figure 18.14 An RS-232 connection is used between a laptop computer (e.g., COM1) and PLC1 for rogramming DH+ is used to connect PLC1, PLC2, and the HMI; it is a proprietary communication standard developed by AllenBradley An operator can use the Human Machine Interface (HMI) to display data and accept operator input and communicate these values directly to both PLCs Devicenet, an open automation standard, is used to connect PLC2 to a welding controller 12/22/16 prof CHARLTON S INAO 139 PLC Analog Inputs and Outputs 12/22/16 prof CHARLTON S INAO 140 12/22/16 prof CHARLTON S INAO 141 12/22/16 prof CHARLTON S INAO 142 Maintenance 12/22/16 prof CHARLTON S INAO 143 12/22/16 prof CHARLTON S INAO 144 12/22/16 prof CHARLTON S INAO 145 12/22/16 prof CHARLTON S INAO 146 12/22/16 prof CHARLTON S INAO 147 12/22/16 prof CHARLTON S INAO 148 12/22/16 prof CHARLTON S INAO 149 12/22/16 prof CHARLTON S INAO 150 12/22/16 prof CHARLTON S INAO 151 The End 12/22/16 prof CHARLTON S INAO 152