I: Introduction to Allen-Bradley Control Systems Family
Allen-Bradley control systems:
1. PLC System: Programmable Logic Controller.
Allen-Bradley line of processors identified by prefix PLC. (e.g., PLC-2®, PLC-3®, and PLC-5® processors)
2. SLC™ System: Small Logic Controller.
Allen-Bradley line of processors with flexibility and power of large processor in size and simplicity of small processor. (e.g., SLC 500, SLC 5/01, SLC 5/05 processors).
3. Logix5000™ System: can integrate
– Process control
Logix5000 control engine available in several platforms/physical formats:
• ControlLogix® - High-performance, multi-controller modular chassis
• FlexLogix™ - Distributed-control
– (i.e., control platform is located at or close to the process/machine.)
• CompactLogix™ - Small modular stand-alone to medium sized
• DriveLogix™ - Distributed drive control
• SoftLogix™ - Combines control, information, visualization on open-control system
– (e.g. control engine housed in computer/other terminal.)
|Logix 5000 Family|
NOTE: ALL LOGIX5000 PLATFORMS WERE PROGRAM BY USING RSLOGIX5000 AS THEY HAVE THE SAME CONTROL ENGINE:
II. Control Logix 5000 Hardware Platform:
• Multi-controller system
• Modular chassis format
• Easy integration with any existing systems (i.e., PLC-5®, SLC™)
• Capable of high-speed communications and data-transfers
• Allow multiple controllers, I/O modules, and communications modules in any order/location within chassis
|PLC Complete Hardware Modular Assembly|
III. Control Logix 5000 Chassis Hardware Assembly.
• Communications modules
• Power supply
|PLC Chassis Hardware Modular Assembly|
NOTE: LOGIX 5000 PLC IS A MODULAR TYPE HENCE EVERY MODULE CAN BE INSERTED INTO THE CHASSIS BY MEANS OF A SLOT.
IV. Standard Sizes Of Control Logix Chassis.
ControlLogix chassis sizes:
|10 Slot PLC Chassis|
NOTE: 1756 (ControlLogix) MODULES ARE NOT SLOT DEPENDENT (i.e., ANY 1756 MODULE CAN BE PLACED IN ANY SLOT IN THE CHASSIS).
V. Control Logix PLC Backplane.
Also known as ControlBus™ backplane:
• Printed-circuit board at back of chassis
• Provides electrical interconnection between modules
|Control Logix Backplane|
NOTE: THE BACKPLANE ALLOWS DATA TO BE MULTICAST (i.e., SENT ONCE AND RECEIVED SIMULTANEOUSLY BY MULTIPLE DESTINATIONS).
VI. Control Logix Processor.
32-bit controller that combines logic and data in modular memory:
|Control Logix CPU|
Controllers have two main internal components:
• Central Processing Unit (CPU): The decision making component that executes the program stored in memory.
• Memory: A group of circuit elements where programs and data are stored.
NOTE: WHEN POWER IS TURNED OFF, THE BATTERY WILL MAINTAIN THE CONTROLLER MEMORY.
VII. 1756-I/O modules provide input/output capability to many applications
I/O modules offer the following capabilities:
• Easy configuration using a wizard
• Electronic module identification (keying)
• Scaling of analog values
• Diagnostics (depending on the module)
Wiring from process/machine connected to I/O modules through one of the following special devices:
• RTB (Removable Terminal Block): field wiring connector for I/O modules.
– Connected to RTB rather than directly to terminal block
• IFM (Prewired Interface Module): field wiring arm that uses prewired/factory wired cable to connect to I/O module.
VIII. Communications Modules
Used for creating communications between controller and network:
Network and their Required Communications Module
- EtherNet/IP™ - 1756-ENBx
- ControlNet™ - 1756-CNB, CNBR, 1756-CN2, CN2R
- DeviceNet™ - 1756-DNB
- Data Highway Plus™ (DH+™) or Universal Remote I/O - 1756-DHRIO
NOTE: FOR SERIAL COMMUNICATION, THE WORKSTATION CAN BE DIRECTLY CONNECTED TO THE CONTROLLER VIA RS232.
|Different Network Protocols Used|
Modular format allows users to design, build, and modify flexible systems:
• Select the number of controllers and appropriate memory size
• Select the number and type of I/O modules
• Select the number and type of communications modules
System can range in complexity:
• Simple stand-alone controller and I/O modules in a single chassis.
• Complex system with multiple controllers, chassis, and networks in different locations.
NOTE: INDIVIDUAL UNITS CAN BE CONFIGURED, REPAIRED, AND REPLACED DUE TO ITS MODULARITY CONCEPT.