1. Copyright 2009 Business Industrial Network www.BIN95.com INTRO TO PLC These are sample slides from presentation one of our instructors customized for NY customer. Customers who receive our PLC Training also received the full version of this PowerPoint with Instructor notes included. See www.BIN95.com to learn more about our PLC training.
5. Programming Instructions AND OTU OSR OTL OTE XIO XIC NOT XOR ADD RPC MVM MOV MEQ GEQ GRT LEQ EQU TDF RHC RES RTO CTD CTU TOF TON DIV MUL SUB DCD CLR DDV JMP FRD TOD Over 100 instructions! 20 of the instructions do 80% of the work! Copyright 2009 Business Industrial Network www.BIN95.com
6. AC Input AC Output Temperature Stepper Control DC Output Digital Input Sourcing Input Sinking Input Analog Input RTD Input Analog Output AC Relay Output I/O Modules High Speed Counters Open Loop Servo Copyright 2009 Business Industrial Network www.BIN95.com
8. Input / Output Modules Each Point is numbered and corresponds to the I/O image table and the I/O device. I/O Hardware / Software Address I:02 O:03/ 00 01 02 03 04 05 06 07 00 01 02 03 04 05 06 07 Each Input device takes on the ID of where it is terminated. PB 1 I:02/02 Each Output device takes on the ID of where it is terminated . LIGHT 1 O:03/05 I:02/2 (Slot 2-Terminal 2) Hardware Address O:03/5 (Slot 3-Terminal 5) I:02/2 (Word 2-Bit 2 ) Software Address O:03/5 (Word 3- Bit 05) Copyright 2009 Business Industrial Network www.BIN95.com
9. BITS, BYTES and WORDS A single binary digit (a bit) corresponds to the condition of a single wire. +5 V +5 V If the voltage is off, the bit value is 0. 0 1 If the voltage is on, the bit value is 1. Copyright 2009 Business Industrial Network www.BIN95.com
10. bit ( b -inary dig- it ) nibble_ 4 bits byte- 8 bits word_ 16 bits Nibble Byte Nibble Nibble Nibble Byte Word BITS, BYTES and WORDS Copyright 2009 Business Industrial Network www.BIN95.com
11. Memory Organization MEMORY DATA PROGRAM File O__ Output Data Table File 1__ Input Data Table File 2__ Status Data Table File 3__ Bit Data Table File 4__ Timer Data Table File 5__ Counter Data Table File 7__ Integer Data Table File 6__ Control Data Table File 8__ Floating Point Data SYS 0__ Forbidden SYS 1__ Forbidden LAD 2 __ MAIN Copyright 2009 Business Industrial Network www.BIN95.com
12. PLC Operating Cycle Input Scan Program Scan Output Scan Housekeeping START Copyright 2009 Business Industrial Network www.BIN95.com
13. PLC Scan Cycle… File O__ Output Data Table File 1__ Input Data Table File 2__ Status Data Table File 3__ Bit Data Table File 4__ Timer Data Table File 5__ Counter Data Table File 6__ Control Data Table File 7__ Integer Data Table File 8__ Floating Point Data Table RAM / Data Tables ROM / Program Files CPU Start Scan Internal Checks Scan Inputs Execute Program Update Outputs Copyright 2009 Business Industrial Network www.BIN95.com
14. PLC Processor 0 1 0 0 0 0 0 0 0 0 Input Data Table 0 0 CPU Scans Inputs Transfers Input Status to Input Table (RAM) Reads Input Table Solves Logic Executes Program Updates Output Table Output Data Table 1 0 0 0 1 1 0 1 0 0 0 0 0 0 0 0 Real World outputs energized / de-energized Inputs Outputs 0 0 0 1 Examine: If TRUE write 1 If NOT TRUE write 0 SCAN CYCLE Copyright 2009 Business Industrial Network www.BIN95.com
PLC Training by Business Industrial Network 12/29/03 www.bin95.com Business Industrial Network www.BIN95.com
Originated from a General Motors Specification for a reprogrammable control device that could be used in place of relays. First level products were available in the late sixties. Initial functions were limited to relay replacement Base PLC design has Input terminals for connection to input devices, and Output terminals for connection to output devices. Product development curve has closely paralleled the PC. Initial products were limited and expensive. As semiconductors have evolved features have increased and costs have fallen. Today's PLC are much much more than simple relay replacers being able to perform complex math, and high speed operations. Size has been significantly reduced. Today's MicroLogix costs approx.. as much as 2-3 relays
SLC 5/01 This processor offers a basic set of 51 instructions with the choice of 1K or 4K of memory in a modular hardware configuration . Modular I/O systems that include an SLC 5/01 processor can be configured with a maximum of three chassis (30 total slots) and from 4 I/O points to a maximum of 3940 I/O points. SLC 5/02 This processor offers additional complex instructions, enhanced communications, faster scan times than the SLC 5/01, and extensive diagnostics that allow it to function in more complex applications. SLC 5/03 This processor provides 8 K, 16 K, or 32 K of memory. A built-in RS-232 channel gives you the flexibility to connect to external intelligent devices without the need for additional modules. SLC 5/04 The standard DH-485 port has been replaced with a DH+ port , providing high-speed SLC 5/04-to-SLC 5/04 communications and direct connection to PLC-5 controllers. The available memory options are 16 K, 32 K, or 64 K. In addition, there is an SLC 5/04P option, which is designed specifically for the Plastics Industry and contains ERC2 algorithms for Plastics Machinery Control. SLC 5/05 The SLC 5/05 processor provides the same functionality as the SLC 5/04 processor with standard Ethernet communications rather than DH+ communications. Ethernet communication occurs at 10 Mbps or 100 Mbps, providing a high performance network for program upload/download, online editing, and peer-to-peer messaging.
Ladder Logic Instructions Ladder logic instructions are the building blocks a ladder program is composed of. You insert instructions onto rungs to create simple executable units of logic. Each instruction performs an operation on variables defined for the target the ladder program is associated with. Tip: All available instructions are contained in the Ladder drawer of the Toolchest. Drag these instructions to a rung in your ladder program. Ladder logic instructions are grouped functionally (that is, according to the type of operation performed). Example of an instruction group : MATH Add (ADD) Divide (DIV) Modulus (MOD) Multiply (MUL) Subtract (SUB)
There are many different kinds of I/O cards which serve to condition the type of input or output so the CPU can use it for it’s logic. There are over 60 different I/O modules to choose from. It's simply a matter of determining what inputs and outputs are needed, filling the rack with the appropriate cards and then addressing them correctly in the CPUs program. Inputs Input devices can consist of digital or analog devices. A digital input card handles discrete devices which give a signal that is either on or off such as a push button, limit switch, sensors or selector switches. An analog input card converts a voltage or current (e.g. a signal that can be anywhere from 0 to 20mA) into a digitally equivalent number that can be understood by the CPU. Examples of analog devices are pressure transducers, flow meters and thermocouples for temperature readings Outputs Output devices can also consist of digital or analog types. A digital output card either turns a device on or off such as lights, LEDs, small motors, and relays. An analog output card will convert a digital number sent by the CPU to it’s real world voltage or current. Typical outputs signals can range from 0-10 VDC or 4-20mA and are used to drive mass flow controllers, pressure regulators and position controls.
Numbers are not given for O: and I:, but they are implied to be O0: and I1:. The number that follows the : is the location number.(Slot and software location) Each file may contain from 0 to 999 locations that may store values. For the input I: and output O: files, the locations are converted to physical locations on the PLC using rack and slot numbers. The addresses that can be used will depend upon the hardware configuration.
Binary numbers are the most fundamental numbering system in all computers. A single binary digit (a bit) corresponds to the condition of a single wire. If the voltage on the wire is true the bit value is 1. If the voltage is off the bit value is 0. If two or more wires are used then each new wire adds another significant digit..
BIT A single binary digit (a bit) corresponds to the condition of a single wire. If the voltage on the wire is true the bit value is 1. If the voltage is off the bit value is 0. If two or more wires are used then each new wire adds another significant digit NIBBLE Four bits makes a NIBBLE BYTE 8 bits makes a BYTE WORD 16 bits (2 bytes )makes a word When data is represented as a series of ones and zeros, it is said to be a binary representation, or to have a base of 2 because it uses 2 digits. The left-end bit of a number represented in binary is called the most significant bit , abbreviated msb , and the right-end bit is called the least significant bit , abbreviated lsb .
Virtually all PLC’s operate using a “Scan” based operating system Input Scan Input device status is “Read” and stored for use during the Program Scan Program Scan The program developed for the application is scanned (solved) using the information stored in the input image (input scan) As each rung of the program is scanned and solved, the processor sets the results of each rung in the output image. Output Scan The information that was set during the program scan is actually written to the outputs (outputs are turned ON or OFF). Housekeeping The PLC checks and updates internal processes for correct operation, checks and deals with communications, and also makes checks that all internal operations are within specifications. Scan Time This entire process (full cycle) is called the processor’s scan time. Typically this time period ranges from 1 to 2 milleseconds (.001~.002 seconds)
MEMORY ADDRESSES The memory in a PLC is organized by data type. There are two fundamental types of memory used in Allen-Bradley PLCs - Program and Data memory. Memory is organized into blocks of up to 1000 elements in an array called a file. The Program file holds programs, such as ladder logic. Program files store users programs in files 2 - 999 _________ 0-2 are fixed There are eight Data files defined by default, but additional data files can be added if they are needed. Only the first three data files are fixed O:, I: and S2:, all of the other data files can be moved . Data files are used for storing different information types. These locations are numbered from 0 to 999. The letter in front of the number indicates the data type. For example, F8: is read as floating point numbers in data file 8. The status S2: file is more complex and is discussed later. The other memory locations are simply slots to store data in. For example, F8:35 would indicate the 36th value in the 8th data file which is floating point numbers
Since a PLC is a dedicated controller it will only process this one program over and over again. One cycle through the program is called a scan time and involves reading the inputs from the other modules, executing the logic based on these inputs and then updating the outputs accordingly. The scan time happens very quickly (in the range of 1/1000th of a second). The memory in the CPU stores the program while also holding the status of the I/O and providing a means to store values. The CPU has different operating modes. In programming mode it accepts the downloaded logic from a PC . The CPU is then placed in run mode so that it can execute the program and operate the process .
PLC Training by Business Industrial Network 12/29/03 www.bin95.com Business Industrial Network www.BIN95.com