Allen-Bradley L1 Processor...

rdrast

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Is there anybody left with a brain at Rockwell/AB?
Why in the world would they decide it is a great idea to name one of the newest CompactLogix processors an L1?

That is the FIRST, OLDEST, and now a COMPLETELY UNSUPPORTED processor in the ControlLogix line. (1756-L1 / 5550).

Rockwell won't even take a 1756-L1 in for trade anymore.
;););););););););)
 
I agree that the naming for the current-generation CompactLogix was clumsy, but then I thought that 'iPad' was a horrible name and that turned out OK.

The family name "5370" doesn't have any connection to the controller part numbers. "5550" and "5555" were the ControlLogix 1756-L1 and 1756-L55 controllers, respectively, but the 1756-L6x and 1756-L7x controllers don't have a family name like that. I realize the "7" was meant to imply that the current generation of CompactLogix use technology from the 1756-L7 family controllers.

You pointed out that RA calls the 1769-L16ER-xxxx and 1769-L18ER-xxxx and 1769-L18ERM-xxxx controllers collectively the "CompactLogix L1 Controllers". At least they use the name CompactLogix and not the bulletin 1756 number.

Remember there were also 1769-L20 and 1769-L30 controllers in the very first generation of CompactLogix. So there's a 1769-L30 that's obsolete, but a 1769-L30ER that is new. Fortunately you can't even attempt to buy a 1756-L1 or 1769-L30, so that's only going to cause confusion on the aftermarket with users who are unfamiliar with the principle of "too good to be true" on eBay.

RA could have pulled out a whole new Bulletin number for the new CompactLogix line, but there's a whole mythological history of Bulletin numbers at Allen-Bradley. They couldn't go from 1769 to 1770.. that's already been used for decades for communication gear. Bulletin 1767 has probably already been reserved by the MicroLogix guys.

My choice would have been to change the part numbers to Bulletin 5370, so you'd have "5370-L16-BB1B". Or just give the smallest controllers a 1734 POINT part number to emphasize their connection with the POINT I/O platform.

Boeing has the same sort of problem, and there's even more mythology built into the "7x7" name. Grown men will throw fits if you refer to a Dreamliner as a 7E7.
 
To make things even worse, they screwed up the logical order of the CompactLogix controllers.

Before the new 5370 CompactLogix they had the:
L31 0.50M Memory
L32 0.75M Memory
L35 1.50M Memory

Now we have the new 5370 CompactLogix the order of increasing memory is like this:

L31 0.50M Memory
L32 0.75M Memory
L30 1.00M Memory
L35 1.50M Memory
L33 2.00M Memory
L36 3.00M Memory

As you can see they are now completely out of order! In my option they should have called the new L30 the L33, the new L33 the L36, and the new L36 something else like L37 or L38. That way you preserved the order! Also trying to convince a client that its an upgrade to move from an L32E to an L30ER is tough, because logically it doesn´t make sense (surely the higher number is better :confused: )

Also they launched the L18ER at a price point far too close to the L24ER, the L18 is only like ~100dollars cheaper, and with the L24ER you can use the normal compact logix expansion cards.

Here in Brazil we have an expersion for these things "coisas de rockwell" which translates litteraly as "things of rockwell" but a more correct translation of the meeting "problems with rockwell"
 
I have, for more years than I care to think about, tried unsuccessfully, to understand any logic to the "family" numbering adopted by RA.

1770, 1771, 1794, 1756, 1769, 1734, 5370, etc., etc..

I've never been able to make a connection of any sort, the numbers do not "progress" in any fashion that I can see.

I get the impression that they have a sweepstake, and pull the numbers out of a hat, suggested by the "committee". Hats off to the guy who put 69 in the hat :unsure:
 
When I hired on at RA, I was convinced that the product names were all references to Frederik Pohl's classic 1978 novel Gateway.

Twos, Threes, Fives, Gateways.... all product nicknames, and elements of the novel. Pohl even skipped the Four. All we really needed next was a General Products Indestructible Starship Hull.

To my surprise, I never once met another employee who had read that book.
 
A-B didn't skip "4". I worked on them briefly in the 80s.
$T2eC16FHJGgFFm6PEV9bBRuyQrcOow~~60_35.JPG
 
Ken Roach said:
You're ruining my theory! Wait until I explain the real story behind Ferris Bueller's Day Off.

Ken...Ferris Bueller's Day Off is one of my all time favs. I gave my son, who's only 8, my old DVD copy a few months ago and he hasn't stopped watching it since, Classic. He laughs his as* off every time, especially at Ed Rooney. "I think you're an A-Hole!" Please don't ruin two generations of childhood chuckles! 🤞🏻

I also bang my head at times when it comes to AB numbering conventions, but I won't let it beat me! I agree that they don't make things easy, but you just need to put on your AB tinted glasses (or blindfold) to figure it all out. :cool:

rdrast said:
Is there anybody left with a brain at Rockwell/AB?
Why in the world would they decide it is a great idea to name one of the newest CompactLogix processors an L1?

That is the FIRST, OLDEST, and now a COMPLETELY UNSUPPORTED processor in the ControlLogix line. (1756-L1 / 5550).

Rockwell won't even take a 1756-L1 in for trade anymore.

rdrast, you're assuming there was a brain there to begin with? :rolleyes:

Once upon a time, in the far off realm of LogixLand...đź“š
There lived a baby 5550 1756-L1 which was the first ControlLogix controller and it started the 1756- bulletin number off. While it had it's own family number of 5550, it effectively only ever represented one controller. So, with the family and the bulletin number removed, the "L1" reference became synonymous as a ControlLogix controller. That was never the intention I'm sure. It came with 160kbytes of base memory and you had the option of memory expansion using the 1756-M1(512KB),M2(1MB) or M3(2MB). So you could order a 1756-L1M1, for instance.

Because many of us are in the habit of abbreviating out the family (5550) and bulletin numbers (1756-) down to just the model number prefix (Lx), it becomes very easy to relate that prefix only to that family of controllers. We then, perhaps, don't expect to see that prefix used again anywhere within the AB controller product range. Again, that's down to our own perception of the numbering convention.

I'm afraid we can't simply look at an AB product in such an abbreviated manner and expect never to see "L1" referenced anywhere else again. Especially so when the older L1 is a discontinued product. Either way, you should look at it from the family level, or at least the bulletin level, as Ken pointed out, and as you quoted:

rdrast said:
...ControlLogix line. (1756-L1 / 5550).

Now compare two full System/Family/Bulletin/Model numbers of the controllers that you think they've named the same. For instance:

ControlLogix 5550 1756-L1
CompactLogix 5370 1769-L16ER-BB1B

When you look at them as full catalog numbers, these are two very different and distinguishable controller catalog numbers.

Bear with me, the grander scheme...

Forget family or bulletin numbers for a minute, and look at these two systems as Logix platforms.

At the model number level, the ControlLogix controllers were assigned L1, L5x and L6x. Then more recently L7x. The gap between L1 and L5x was filled mainly by the original CompactLogix L2x, L3x and L4x models (FlexLogix got 2 of the L3 model numbers).

The CompactLogix, being the lesser of these two Logix systems, was assigned the lowest available controller model numbers, but they made the mistake of starting the first ControlLogix at L1, so the CompactLogix could only use L2, L3 and L4. Otherwise the CompactLogix would have always been L1, L2 and L3.

As they knew the ControlLogix L1 was being discontinued, they introduced the new CompactLogix controllers at L1, along with the replacement L2 and L3 models and all is right in LogixLand. But not in UserLand. :unsure:

CompactLogix and ControlLogix controllers, as they are continuously replaced with their newer versions, are being positioned as the main Logix platforms going forward. So they are re-aligning the Logix controller model numbering to start at L1-L4 for the CompactLogix and L5-L7 for the ControlLogix, or there abouts. The L5x controllers have all been discontinued bar one. So whether the CompactLogix will get the L5x slot for the future, or the ControlLogix will hold onto it, who knows? L8x controllers will probably arrive in the not too distant future. But either way, this re-alignment is, I'm sure, intended to make sense some day.
-------------------------------------------------------
The newer CompactLogix Family of controllers are the 5370 L1, 5370 L2 and 5370 L3.
They use L1, L2 and L3 because they're the prefix for the controllers within each of those model ranges:

5370 L1 Controllers:
5370 1769-L16ER-BB1B
5370 1769-L18ER-BB1B
5370 1769-L18ERM-BB1B

5370 L2 Controllers:
5370 1769-L24ER-QB1B
5370 1769-L24ER-QBFC1B
5370 1769-L27ERM-QBFC1B

5370 L3 Controllers:
5370 1769-L30ER
5370 1769-L30ERM
5370 1769-L30ER-NSE
5370 1769-L33ER
5370 1769-L33ERM
5370 1769-L36ERM
------------------------------------------------------------
The old and mostly soon to be discontinued CompactLogix controllers include:

The Packaged Controllers with Embedded I/O:

L2:
5320 1769-L20 Discontinued
5323 1769-L23-QBFC1B Silver 2015
5323 1769-L23E-QB1B Silver 2015
5323 1769-L23E-QBFC1B Silver 2015

The Modular Controllers:

L3:
5330 1769-L30 Discontinued
5331 1769-L31 Discontinued
5332 1769-L32C Silver 2015
5332 1769-L32E Active (Ethernet model retained for now)
No............L33 >>> FlexLogix used 5433 1794-L33 Discontinued
No............L34 >>> FlexLogix used 5434 1794-L34 Discontinued
5335 1769-L35CR Silver 2015
5335 1769-L35E Active (Ethernet model retained for now)

Dual Backplane CompactLogix Controllers:
Supports 1768 and 1769 backplanes simultaneously.
Around for another good while.

L4:
5343 1768-L43 Active
5345 1768-L45 Active

and their GuardLogix equivalents:

5343 1768-L43S Active
5345 1768-L45S Active

Note: the L4 bulletin number of 1768, so the CompactLogix family uses 1768 and 1769.
------------------------------------------------------
Within the ControlLogix family, old and new, you have:

L1: Discontinued
5550 1756-L1
5550 1756-L1M1
5550 1756-L1M2
5550 1756-L1M3

L53: Discontinued
5553 1756-L53

L55: Discontinued
5555 1756-L55
5555 1756-L55M12
5555 1756-L55M13
5555 1756-L55M14
5555 1756-L55M14K (Conformally Coated) Active
5555 1756-L55M16
5555 1756-L55M22
5555 1756-L55M23
5555 1756-L55M24

L6: Active
5561 1756-L61
5561 1756-L61S
5562 1756-L62
5562 1756-L62S
5563 1756-L63
5563 1756-L63S
5563 1756-L63XT
5564 1756-L64
5565 1756-L65

L7: Active
5571 1756-L71
5571 1756-L71S
5572 1756-L72
5572 1756-L72S
5573 1756-L73
5573 1756-L73S
5573 1756-L73XT
5574 1756-L74
5575 1756-L75
-------------------------------------------------------------------
Ken Roach said:
RA could have pulled out a whole new Bulletin number for the new CompactLogix line, but there's a whole mythological history of Bulletin numbers at Allen-Bradley.

Ken, I don't really see why they needed to? The newer 5370 family retained the 1769 CompactLogix bulletin number simply because they are still classed as CompactLogix controllers. They're just replacements for the old 1769 ones that are half retired. It's just a PITA in the interim period sorting out what's what. When they assigned bulletin numbers long long ago, they didn't leave large enough gaps for so many new product ranges. So now they're faced with a dilemma. But...

Ken Roch said:
My choice would have been to change the part numbers to Bulletin 5370, so you'd have "5370-L16-BB1B".

I concur captain!

Another thing they seem to be correcting. All the older CompactLogix controllers pretty much have their own family number, but note how the new ones use the same family number of 5370 for all the controllers. A family number should be just that, a single number, not one for each controller.

5370 CompactLogix family number:
5xxx = 5000 Logix Platform
x3xx = CompactLogix System
xx70 = Controller Architecture

556x & 557x ControlLogix family number:
5xxx = 5000 Logix Platform
x5xx = ControlLogix System
xx6x = L6 Controller Architecture
xx7x = L7 Controller Architecture

So, they could possibly also re-align the ControlLogix family numbers to one number in the future. That way the CompactLogix could drop the 1769- for 5370- and ControlLogix could drop the 1756- and use something like 5570-?

It'd make life a lot simpler all right. Maybe then the people of LogixLand :geek: and UserLand 🔨 could live happily ever after...🍻

The End.

This is a handy Selection Guide for the 1756 Series controllers which has a comparison table for all ControlLogix and CompactLogix controller features.

G.
 
Last edited:
Just to make some sense of this...
Usireland said:
...they screwed up the logical order of the CompactLogix controllers.

Edits in RED

Before the new 5370 CompactLogix they had the:

5330 1769-L30 1.00M Memory <<< Discontinued (added for clarity)
5331 1769-L31 0.50M Memory <<< Being phased out
5332 1769-L32 0.75M Memory <<< Being phased out
5335 1769-L35 1.50M Memory <<< Being phased out

Now we have the new 5370 CompactLogix the order of increasing memory is like this:

5370 1769-L16x 384KB
5370 1769-L18x 512KB
5370 1769-L24x 750KB
5370 1769-L27x 1MB
5370 1769-L30x 1MB
5370 1769-L33x 2MB
5370 1769-L36x 3MB

USireland,

Sorry to have redone your bottom list, but they don't intend for us to try sort the old and new together in a list that doesn't make much sense. Whatever controller spec you want to compare, you need to look at the older controllers list and then the newer controllers list. Each older controller has a newer compatible, or better model available.

USireland said:
Also trying to convince a client that its an upgrade to move from an L32E to an L30ER is tough, because logically it doesn´t make sense (surely the higher number is better

Your obviously not a good salesman! :whistle:

There are many features you can push besides a model number...
greater user memory, more controller and network connections, no battery, dual Ethernet, SD card, backward compatible with 1769 I/O, easy program transfer, future-proof, less expensive spares, etc.

USireland said:
Also they launched the L18ER at a price point far too close to the L24ER, the L18 is only like ~100dollars cheaper, and with the L24ER you can use the normal compact logix expansion cards.

So you've spent the extra 100 for what? 1769 I/O compatibility? That's good value if that's what you want for the job. You'd get double the user memory on the base unit as well. But you might now have a more expensive expansion platform that you may not want. The 1769 I/O modules will be more expensive than 1734-POINT I/O.

It's like selling a good car and a luxury car at nearly the same price. You can afford to run the good car, but can you afford to run the luxury car?

For a small job the L18ER is good value comparably, and if you do need some expansion I/O, the 1734-POINT I/O will most likely do just as well at a lesser cost.
Pricing, especially when it's that close, should not really have a bearing on your choice at all. It should be more down to what platform suits the application.

G.
 
When I hired on at RA, I was convinced that the product names were all references to Frederik Pohl's classic 1978 novel Gateway.

Twos, Threes, Fives, Gateways.... all product nicknames, and elements of the novel. Pohl even skipped the Four. All we really needed next was a General Products Indestructible Starship Hull.

To my surprise, I never once met another employee who had read that book.

I've actually read the entire series (Gateway, Beyond the Blue Event Horizon, Heechee Rendevous, and Annals of the Heechee for those that aren't familiar), and have them all in hardcover. I keep hoping for them to be released in a Kindle edition.
 

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