Hi
I am using diffrent ROCKWELL PLCs as mentioned Below:

ML100
ML1500
1769-L31
1756-L55M23

I want to know,
1)when this PLCs came in to market?
2) is This PLCs working with any RTOS apart from the Firmware?
3)For what application Control Logix is meant for, since compare to Compact Logix PLC is high processing speed compare to controlLogix?

Thanx in advance
Satheesh.G

I am curious about why it matters what OS is in the embedded system. I would be more interested in whether the models are being currently produced, and what upgrade paths there are for future support.

These are not official Rockwell Automation answers; they are just my recollections.

MicroLogix 1000 was introduced around 1995. New features were introduced to add DH485 and DF1 Half Duplex support in the late 1990's, but the product has been essentially static since 2000. There are no plans to discontinue or change the MicroLogix 1000. Its operating system is proprietary and is most similar to the SLC-5/02 controller.

MicroLogix 1500 was introduced around 2001. Because it has flash memory for firmware, development and features have been continuously added and continue today (FRN 11 is current). New hardware versions of the MicroLogix 1500 are unlikely, as most new development is being done on independent codebases for the MicroLogix 1100 (2005) and 1400 (2008) controllers. The MicroLogix 1500 controller's firmware is most similar to that of the SLC-5/03 controller.

ControlLogix 1756-L55M23 was introduced around 2001. The "M23" designates nonvolatile memory, with the largest available (8 MB) controller RAM size. It will run firmware up to Version 16 (2007). While this specific controller is no longer being manufactured, its successor the 1756-L63 is readily available and can run most firmware that was available for the 1756-L55. ControlLogix is the largest and fastest controller built by Rockwell Automation. The operating system of the controller is proprietary.

CompactLogix 1756-L31 is the smallest of the second-generation CompactLogix controllers. It is a current product and will run the latest (v17) firmware for the CompactLogix family controllers.

ControlLogix is generally a "system" controller; it can support dozens of remote chassis, up to 31 axes of motion control, and can run routines as fast as 1 millisecond or as slow as several seconds. A ControlLogix generally runs a large machine or machine system. ControlLogix has modular communications (Ethernet, ControlNet, DeviceNet, Profibus, Modbus, RIO/DH+, etc) and a chassis-based I/O system that allows modules to be inserted and removed under power.

CompactLogix is generally a "machine" controller. The I/O is a "rackless" design that cannot be modified under power. The smaller CompactLogix (L31, L32x, L35x) do not support motion control, and the larger CompactLogix (L43, L45) suppport between 4 and 8 axis over SERCOS fiber optics.

MicroLogix family controllers use operating systems, data addressing, and instruction sets similar to the SLC-500 controllers. Programs are created, edited, and monitored with RSLogix 500 software.

CompactLogix and ControlLogix controllers use the modern Logix operating system an the RSLogix 5000 programming environment.

Sure, those PLC's will work "with" an RTOS. If you mean replacing the OS with something else, no can do. There have been various "system on a card" systems that plug into the chassis and run alongside the PLC for years. The most interesting one I can recall is the 1771-DMC which was a complete OS-9 based system on a card. The most memorable experience is dealing with someone else's software loaded on it though, and it wasn't pretty!

The more typical way that you set them up to work with an RTOS is that you set up your RTOS on an embedded system right next to the PLC and they talk to each other either through discrete I/O, serial, or Ethernet.

ControlLogix is big, really big. You can run pretty much an entire chemical or other large "process" plant on a single system. Or going in the other direction in discrete manufacturing, you can run an entire large robot system with multiple robots using the ControlLogix as the controller. A-FAST Robotics has actually been producing a few smaller examples of this already. There's no controller, just a bunch of drives and hardware. The PLC is the controller. The ControlLogix has very fast speeds (sub-millisecond scan times) specifically because it's the equivalent of a multi-core, multi-CPU server to put it in PC terms. The CompactLogix on the other hand is much more limited in size and horsepower.

I haven't really seen any programs yet that truly begin to tax the capabilities of a ControlLogix system to it's limits. Conventional wisdom about how "big" a PLC system should get seems to be more of a limiting factor.

Hi Satheesh,

To answer your question, Rockwell has partnered with Wind River and uses their RTOS, VxWorks, in its products. I think that does matter very much when it comes to the credibility of the design. Rockwell is not trying to reinvent the wheel.

This may not directly affect anything you need to do with a Rockwell PLC, but when people complain about using a PLC instead of PC-based control it helps to know a little more about the platform. A Rockwell PLC in its current form is really a specialized firmware and hardware package with a general purpose RTOS. The old ideas of what a PLC were are sometimes stuck in the heads of many who aren't up to date.

ControlLogix has the greatest IO, memory and processing capacity of the Rockwell offerings. CompactLogix has a reduced footprint, price, and scalability.

Good luck,
Lindsey Eastburn