AB ControlLogix vs CompactLogix

I've been looking at some of the upcoming jobs we're doing where I work, and I feel like the scale would justify a ControlLogix instead of the CompactLogix we typically use, but I still can't figure out what the real benefit would be as the current generation of CompactLogix is pretty similar to the CLX. Are there specific cases where CLX is required? I know previously you could only get SIL3/Cat4 safety in the Guardlogix with safety partner, but AB just released the SIL3/Cat4 version of the Compact Guardlogix, so that's not even a factor anymore.

One major difference is the CLX can have certain nodes added or modified online while a CPX cannot.

The major difference is the amount of memory.
If you can do all you need in a CPX, why spend the money for a CLX.

If you are using the Plant PAX objects, they are resource hogs. In the CLX line a L73 is the recommend minimum CPU. For small projects I have gotten by with a L71, but they had limited IO.

I have not attempted a PAX project in a CPX yet.

Based on previous designs, we always try to specify ControlLogix rather than CompactLogix, as we want to use one Ethernet module for Industrial Network and SCADA, and a separate module/port for remote I/O like Point/Flex/Drives.

Not sure if CompactLogix does dual addressed ethernet ports yet, but that was our main limitation previously, as you could not add a suitable comms module to the rack

if this is a "high speed" application, then there are some considerations with how the COMPACT-Logix handles its I/O signals ... not that it can't handle them - but there are some settings related to the Task Priorities that might need to be tweaked when moving from the CONTROL-Logix platform ...

if you're interested, here are a couple of files to demonstrate ... change the extension of each of them from .ZIP to .WAV and see if you can get them to play ... there's a "marker tone" about halfway through each file where the Task Priority settings are changed ... note that the COMPACT-Logix has some "issues" after that point - but the same program running in a CONTROL-Logix system works fine all the way through ...

DISCLAIMER: this experiment was set up several years ago as a demonstration for one of my customers ... later models of COMPACT-Logix might have solved this "issue" - so your mileage may vary ...
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JohnCalderwood said:

Based on previous designs, we always try to specify ControlLogix rather than CompactLogix, as we want to use one Ethernet module for Industrial Network and SCADA, and a separate module/port for remote I/O like Point/Flex/Drives.

Not sure if CompactLogix does dual addressed ethernet ports yet, but that was our main limitation previously, as you could not add a suitable comms module to the rack

Click to expand...

The newer 5380 compactlogix can do dual IP starting with firmware v30 I think. Working on a project right now where I'm doing that. Obviously you can't do DLR if you're in dual-IP mode though.

piratedan200 said:

The newer 5380 compactlogix can do dual IP starting with firmware v30 I think. Working on a project right now where I'm doing that. Obviously you can't do DLR if you're in dual-IP mode though.

Click to expand...

Well you can, you just need to add additional hardware like the 1783-ETAP or 1783-NATER

CompactLogix vs ControlLogix:

- Is it a skid system? CompactLogix is probably all you need
- Distributed? ControlLogix for scalability

Memory?
- Is there a lot going on in the program? ControlLogix
- Not much? CompactLogix

IO Requirements?
- Lots of Ethernet/IP based IO, VFDS, remote IO racks..etc? ControlLogix
- Little IO, located in same cabinet or only a few Ethernet/IP devices? CompactLogix.

Networking?
- Need many separate network connections, PLC to PLC, SCADA, IO? ControlLogix
- Only a few, IO/HMI? CompactLogix

Do you need unique/specialty cards? ControlLogix
- ControlNet (dated example)
- DeviceNet (dated example)
- High Speed counters?
- High density RTD?
- Weigh Scale Modules?
- OPC-UA module?

Paullys50 said:

Well you can, you just need to add additional hardware like the 1783-ETAP or 1783-NATER

Click to expand...

So, you decide to build a ring for redundancy/resilience, but the most important bit of the ring (the PLC) sits outside it? I really can't understand how people justify this as acceptable.

Paullys50 said:

Do you need unique/specialty cards? ControlLogix
- DeviceNet (dated example)

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Does Rockwell have any fieldbus currently supported that isn't Ethernet?

I'm looking at upgrading a system and have to keep deviceNet as there isn't another fieldbus system that doesn't involve replacing all the valve actuators and indicators in the plant.

Does Rockwell have any fieldbus currently supported that isn't Ethernet?

I'm looking at upgrading a system and have to keep deviceNet as there isn't another fieldbus system that doesn't involve replacing all the valve actuators and indicators in the plant.

Click to expand...

DeviceNet is not dated...
Still very much supported, it had better be, as I have lots of I/O on different Rockwell platforms that we still use and I have no wish to try and recable...
Just negotiating upgrading 1336Plus drives on DN to Powerflex with a DN interface, and also use GE I/O on DN with a ControlLogix, never mind all our DN I/O on PLC5..

cardosocea said:

So, you decide to build a ring for redundancy/resilience, but the most important bit of the ring (the PLC) sits outside it? I really can't understand how people justify this as acceptable.

Click to expand...

Then it is designed wrong and pick a better suited controller? Not all CompactLogix PLCs have dual Ethernet, and you can't always add additional com cards to the CompactLogix line. Pretty much ended with 1768. So pick the controller required for the design that is required.

JohnCalderwood said:

DeviceNet is not dated...

Click to expand...

Dated != not supported.

Is anybody supplying NEW systems w/DeviceNet? (excluding those who require it to match existing equipment...)

I don´t see if anybody said that with contrologix you can change modules in line, but with compact you have to turn off the whole thing.