SLC vs CLX

I am currently using AB SLC 5/05's in substation automation. I am by no means an expert in AB stuff and I recently borrowed a CompactLogix PLC from a contractor that we sometimes employ. I have been dabbling in RSLogix 5000 to try and get a feel for the differences. What advantages does the CLX and Logix 5000 offer over the SLC and Logix 500. So far I don't see any major differences in the software (I'm talking about ladder) other than the different languages. I guess that the ControlLogix line has more comm options but over all I haven't seen a huge difference. Is the CLX line and Logix5000 large leap in capability?

Thanks.

Steve

Check for some old threads on this website. I got bashed up once for asking this question at this forum. You may want to check up with previous threads posted on this site before you may think of posting questions.

the answer to your question is yes..to me..it seems like a quantum leap..from RS 500 to RS 5000..( i mean both hardware and s/w wise)

Substation automation usually requires some communications via radio. Both are very capable in that aspect, but one other thing comes to mind, and that is the ability to store more data if comms are lost. With that in mind, I think you will find it easier to implement in CLx only because of the data array function of CLx and the vast memory offered!

just a bitmore

In a nutshell the answer is yes. In the long run you will probably be making the change to the new CLX family anyhow.

The single biggest feature that I use extensively is the ability to create User Defined Datatypes (UDT's). These very handy objects hugely assist in creating far more strutured and better commented logic, and substantially reduce developement time.

Sequence of Events (SOE) modules are now available for CLX that may be of interest in substation automation, along with some very cool GPS time stamp modules to allow sub millisecond time resolution over wide geographic areas.

As Ashwin mentioned there are far more flexible comms options, both from Rockwell and third parties. The native ability for comms to bridge across the backplane from any one port to any other is also very cute.

I've been using CLX since it was launched over 6 years ago, and I only use SLC or Micro if there are client driven reasons to do so.

On the other hand if SLC is currently meeting all your needs (and it sounds like it is) then there is no pressing need to make the change. Having said that it might also pay to consider that SLC has now been in the market almost 17 years and is probably in the last third of its commercial life, so eventually the change will need to be made...so why not now?

PhilipW has some points but he forgot to mention that the only way to "drill down" through the backplane is with the "ethernet bridge" module types. Example ANET modules will NOT bridge the Comms whereas ANBT do. He is also right about the availability of 3rd part comm cards like the Prosoft offering for Modbus.

There is also the fact that with SLC the I/O refresh is synchronised with the program cycle, while in the CompactLogix this is not the case. CompactLogix I/O is refreshed every 2ms independant from the program cycle.

SLC is single tasking, while CompactLogix is multitasking. This quote is taken fom the help file:

Logix5000 Execution Model
The controller operating system is a preemptive multitasking system that is IEC 1131-3 compliant. This environment provides:

• tasks to configure controller execution
• programs to group data and logic
• routines to encapsulate executable code written in a single programming language

The operating system is preemptive in that it provides the ability to interrupt an executing task, switch control to a different task, and then return control back to the original task after the interrupting tasks are executed. In any given task, only one program is active at a time.

Task
A scheduling mechanism for executing a program. A maximum of 32 programs can be scheduled to execute when a task is triggered. A task can be configured to run as a continuous task or a periodic task. A maximum of 32 tasks can be created to schedule programs.

Program
A set of related routines and a collection of tags. When a program is executed by a task, execution of logic starts at the configured main routine. That routine can, in turn, execute subroutines using the JSR instruction. If a program fault occurs, execution jumps to a configured fault routine. Any of these routines can access the tags in the collection, however, routines in other programs cannot access the tags.

Click to expand...

I have found there's quite a difference between the two. But when it comes to the ladder routines, they look pretty much the same. At least there's consistency of instruction set. Compare that to the various Siemens models (eg. S7-200 and S7-300).

Kind regards,

As far as comm options go there is a big difference in options between the ControlLogix and CompactLogix systems. Both are based on the same logic engine and have an identical 'look and feel'. However, the CompactLogix offering has significantly fewer comm options than the ControlLogix platform. I think this is both intentional (product differentiation) and situational (the CompactLogix hasn't been around as long). To the best of my knowledge as of right now AB directly provides serial, Ethernet, Controlnet and Devicenet interfaces. I'm not sure what third party stuff you can get in CompactLogix. CompactLogix also has fewer specialty modules than the ControlLogix offering.

To expand on Bitmore's comment about bridging, any of the 'bridge' comm modules support bridging. I have done bridging with the ENTB, the CNB (Controlnet) and the DNB (Devicenet) modules. As he said, the ENET module did not support bridging but it was not a 'bridge' but a direct interface module. I don't even know if you can get a new ENET anymore.

Keith

Thanks for the part number correction! I knew what I meant and I'm glad you helped with the part numbers.

To correct once again.

kamenges said:

I have done bridging with the ENTB...

Click to expand...

Bitmore said:

Thanks for the part number correction! I knew what I meant and I'm glad you helped with the part numbers.

Click to expand...

I am guessing you are talking about the ENBT?

Well if I keep trying someday I'll get it right, just one of those whatcha-ma-callit's and a thinga-ma-bob and don't forget them cables!
1756-ENBT A CAT. REV. B01 PART NO.96347274 A01
Thats the one... that one is a bridge!

1756-ENET/B CAT. REV. A01 PART NO.96383071 A01
That one is not!

Gotta nitpick just a little (hey, it's past midnight.)

The 1756-ENET and 1756-ENBT are both Ethernet to Logix backplane bridge modules.

The difference is like so:

1756-ENET Series A Messaging Only
1756-ENET Series B Messaging and I/O, 900 frames/sec
1756-ENBT Series A Messaging and I/O, 5000 frames/sec

All the other info in the thread is spot on. I sell mostly SLC-5/05 into substations in my region, with ControlLogix being adopted mostly for conversions from TI-505 and for the new SOE modules.

I knew this thread would drag up a few roaches!
Must be my 1756-ENET/B CAT. REV. A01 PART NO.96383071 A01 needs a firmware update!