L1 vs. L55

Allen Nelson · Nov 22, 2004

I've tried looking through the literature.

What are the differences (besides price, and assuming comperable memory upgrades) between the ControlLogix 1756-L1 processor, and the ControlLogix 1756-L55 processor?

Is the L1 being made obsolete by Rockwell? What's the deal there?

And if I missed it, where can I find the comparison chart? It doesn't seem to be at http://literature.rockwellautomation.com

grs · Nov 22, 2004

I couldn't find any sort of comparison chart, however, according to this link, they are scheduled for silver series next summer.

http://www.ab.com/silver/controllogix.html

msinclair · Nov 22, 2004

Looks like there is a significant jump in "standard" memory. The L1 has 160K base (though it is expandable), while the L55 seems to start with ".5 MB Expansion memory".

I haven't used these myself, so I don't know if anything in the architecture changed to use/eliminate the base memory and/or speed up access to the expansion memory.

Not much info, but look here .

Marc

Allen Nelson · Nov 22, 2004

L55 vs. L6x

Thanks for the quick reply. :site:

If anyone wants to compare the ControlLogix 1756-L6x and the others, it would be a goodness (again, ignoring price and assuming comparable memory).

The real question is: When do you select one over another?

msinclair · Nov 22, 2004

Hi Allen,

It doesn't have everything you want, but this and this are what I found on the AB site.

Marc

msinclair · Nov 22, 2004

Just found this too.

Contr_Conn · Nov 22, 2004

A-B is not making and selling L1(Logix5550) processors for 3 or 4 years already.
They just can't get ICs and memory anymore.
Ver 13 of ControlLogix is the last version to support L1 processors as well as Flexlogix L33.
L55(Logix5555) will be in production for a few more years, but if you are working on the new project definately look L6x series.
I was told that new L6x processors (series B) coming out very soon.

RSL · Nov 22, 2004

We just bought an L62 with 4MB memory for a little less than I could get an L55M14 with 3.5 MB memory.

With support for compact flash cards, I thought the choice was easy.

The only upside to the L55's I can think of is the memory expansion.

They are supposed to be much faster too.

By the way, I also had no idea what the difference between L1's and L55's was.

RSL

Contr_Conn · Nov 22, 2004

As of today it makes no sence to buy L55 processors, as well as L1 which is no avalable anyway.
L6x can do all L55 can do.
As menitoned above for less money you would be paying for L55 you will get with L6x:
- more stable processor
- same or larger RAM memory
- much faster logic execution
- 64MB compact flash were you can dynamically save your data

The only drawback: L6x uses battery faster than L55

grs · Nov 23, 2004

The only drawback: L6x uses battery faster than L55

Agreed. The battery module (1756-BATM) is a must with these processors.

Contr_Conn · Nov 23, 2004

Agreed. The battery module (1756-BATM) is a must with these processors.

New L6x Ser B will not have this problem - it will use battery during shutdown process only while saving data to CF.
It will be using new battery also

grs · Nov 23, 2004

Cool. Didn't know that. Thanks.

drewcrew6 · Nov 24, 2004

Was just about to ask about why the battery drain on the whole family of these proc. I still don't understand why with all the non-volitile memory around why do those proc even need a battery let alone a monster (1756-BATM).

Drewcrew6

Contr_Conn · Nov 24, 2004

I still don't understand why with all the non-volitile memory around why do those proc even need a battery let alone a monster (1756-BATM).

For L55 processors it is very costly to have EEPROM option.
CF card for L6x is much cheaper solution,

Keep in mind that every time you restore from CF or EEPROM, all data tables will be restored to the original values.

Also in order to write your on-line program changes to CF you have to put processor in Program Mode - it is not always possible.

L6x series B should partially relove this issue - will see how it goes.

Klaus · Nov 24, 2004

The L55 is newer and a little bit faster than a L1. The memory size of a L55 is fix, a L1 was designed do replace the memory card by the user. There's a overview regarding the scantime of the instructions between the L1 and the L55. If you're interested in this, I can have a look for this. The 6x is the newest generation of processors. It's faster than the L55, especially for motion instructions. You need a newer Firmware/Software to handle this, for the 63 version 12 is ok, but for the 61 and 62 you need 13. The L55 is running with version 7 (?) and newer.

If you have a new project you should select the 6x family.

L1 vs. L55

Allen Nelson

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Allen Nelson

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