Allen Bradley FlexLogix PLC range
By Subhash Kandpal
The Allen Bradley ControlLogix PLC,Allen Bradley CompactLogix PLC and Allen Bradley FlexLogix PLC systems have been developed by Allen Bradley part of the Rockwell group of companies based in the USA. It is a highly advanced state of the art PLC system that utilises technologies that have been developed by Rockwell Automation over the last 30 years.
There are 2 Rockwell FlexLogix processor options the L33 with 64K of memory and the L34 with 512K of memory. Apart from the memory specification the operation of the units is identical.
An Allen Bradley FlexLogix system provides a multi-purpose programmable controller. I/O can be distributed to locations close to sensors/actuators. Multiple FlexLogix controllers can be connected in networks for distributed processing of larger systems.
Because it has a Logix control engine, a FlexLogix controller supports the Logix instruction set, tasking model, and data model. A FlexLogix controller as with other Logix controllers have a common approach to programming and configuring I/O with RSLogix 5000 programming software. The Flex 1794 I/O products offer a range of digital and analog I/O (including intelligent I/O) in a rugged modular assembly. A simple FlexLogix system can consist of a single, stand-alone assembly with one controller and as many as eight I/O modules. With an extra local expansion a further 8 modules can be added locally. FlexLogix systems can be mounted either horizontally or vertically. An optional extension interconnect cable can be used to place I/O modules closer to field devices. In a more complex FlexLogix system, Ethernet, ControlNet or DeviceNet networks can be used to connect distributed I/O platforms over multiple I/O links.
If you use multiple FlexLogix systems, you might want one central controller, such as a ControlLogix controller, to coordinate the FlexLogix controllers. If the FlexLogix controller uses remote I/O, place it on its own network. If you plan to share I/O, make sure the I/O is on a network that each controller can access locally.
Each FlexLogix controller can support:
8 local I/O modules.
8 extended-local I/O modules.
32 connections per communication card over ControlNet or EtherNet/IP.
(two communication cards per controller maximum).
496 input bytes and 492 output bytes over DeviceNet.
Allen Bradley FlexLogix controllers have an RS-232 (DF1 protocol) port built into the processor. Two separate communication interface module slots are available for a variety of communication options. These are, EtherNet/IP, ControlNet, and DeviceNet communications cards. If you use different communication interface modules into the FlexLogix communication slots, you can bridge and route data between the RS-232, ControlNet, EtherNet/IP, and DeviceNet networks.
EtherNet/IP is an open industrial networking standard that supports implicit and explicit messaging and uses commercial, off-the-shelf Ethernet equipment and physical media.
ControlNet allows intelligent, high-speed control devices to share the information required for supervisory control, work-cell coordination, operator interface, remote device configuration, programming, and troubleshooting.
DeviceNet offers high-speed access to plant-floor data from a broad range of plant-floor devices and also offers a significant reduction in wiring.
About the Author
Author is and Automation training company http://www.dat.co.uk/ who offer a wide range of Automation course for PLC's (Programmable Logic Controllers), SCADA and HMI systems and variable speed drives.
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| Some other articles by Subhash Kandpal|
|Selecting a Allen Bradley ControlLogix network.|
Communication is at the core of the Allen Bradley ControlLogix PLC platform. The following networks are available for a ControlLogix rack.