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Old March 9th, 2018, 05:18 AM   #1
phuz
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1756-L7X vs 1756-L8X

Having heard about the Intel quad core in the new L8 series processors, I was eager to get a new project where I could use one. That day came and I was even more amazed than I thought.

I took a program I have been developing in my bench L73 and dumped it in the new L81E and this is the difference in scan time. Simply incredible.
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Old March 9th, 2018, 06:24 AM   #2
jstolaruk
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3500% improvement? Almost seems unfathomable.
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Old March 9th, 2018, 07:18 AM   #3
Geospark
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I have not, nor probably will not, ever get my hands on one to play with, let alone use in a running application. So I am somewhat envious of you. Do please enjoy your privileged position.

Their specification, I remember, touted an impressive improvement scan time over their predecessors - up to 20x improvement in the standard task. A possible 200us I/O update time was also advertised.

If we take your Max Scan times for the same Task as an example, that is roughly 35x faster. That is quite impressive.

Quote:
Originally Posted by phuz
Having heard about the Intel quad core in the new L8 series processors...
On the quad-core front, just a small but important distinction to make - They are achieving these remarkable improvements by virtue of the fact that there are multiple dedicated processor cores available, more so than actually using all available cores to achieve such scan times. Other controller tasks, such as motion, unconnected messaging and CIP communications do not impact upon the program tasks as they also have dedicated cores available...

These controllers with memory will utilize the new ICE2 ASIC as their host CPU. The ICE2 ASIC has a quad-core Cortex-A9 architecture which will allow for separation of main logic execution from auxiliary functions such as communications and packet processing. This equipment utilizes three cores of the ASIC.

If you want to view more statistical and diagnostic data for your controller then you can open its built-in web pages via a web browser. These controllers use these web pages instead of the Logix5000 Task Monitor. The scan times are also available there.

Another tidbit to add - If you convert a project from say an L7 to an L8, then you cannot convert back. They are too incompatible as the controller architectures are completely different. I hope you saved an L7 copy of your test project should you still need it!

To view some more impressive sample improvement task times take a look at this promotional video which I remember viewing some time ago...

ControlLogix 5580 Performance

It compares the L7 and L8 platforms, which is quite pertinent to the thread title.


Regards,
George
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Last edited by Geospark; March 9th, 2018 at 08:13 AM.
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Old March 9th, 2018, 08:48 AM   #4
benaiahhenry
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Quote:
Originally Posted by phuz View Post
Having heard about the Intel quad core in the new L8 series processors, I was eager to get a new project where I could use one. That day came and I was even more amazed than I thought.

I took a program I have been developing in my bench L73 and dumped it in the new L81E and this is the difference in scan time. Simply incredible.
Those L8's really are impressive. On one application I converted I also got about 35x improvement, on the other one I got about 15x.

I'm looking forward to the PLd Safety version of that coming out that doesn't need a safety partner.

-Benaiah
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Old March 9th, 2018, 09:31 AM   #5
JohnCalderwood
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We had an L83 installed on a Press Line late last year.
It was put in for a small application, with a view to also using it to replace 3 of our 1785-L80C PLCs, which control the rest of the Press. So all control functions will end up in one PLC.

While I appreciate the improved performance, the main issue I have just now is in our Transaction Manager data collector, which was set up only 4 years ago.
It has Microsoft Windows Server 2007, RSLinx Classic 3.6/Enterprise 5.4 and communicates with 25 PLCs.....but not with the new L83....
To do so, we need to upgrade to the latest version of RSlinx, which will also mean an upgrade to MS Windows Server and associated programs..

One of my corporate engineering colleagues suggests that it may be an issue with the new onboard Ethernet port, and suggests we install a 1756-EN2T card in the rack and try that for communications...
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Old March 9th, 2018, 09:36 AM   #6
harryting
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Rough price differential?
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Old March 9th, 2018, 09:39 AM   #7
JohnCalderwood
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UK List Price :

L73 - 6850
L83E - 7430
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Old March 9th, 2018, 09:44 AM   #8
dmroeder
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Yeah I was a little surprised that it wasn't just marketing, they really do perform. I spoke to a forum member her yesterday about an upgrade from a L7x to a L8x, their scan time went from a peak 200ms to a peak 7ms. What was really neat was the scan time didn't really vary, stayed steady at 7ms, most likely because of what George mentioned regarding how the multiple cores are used.

I did a test a few months ago reading/writing data using it's gigabit port. A combination of ~1100 read/write of a mixed tag data types. The L75 via EN2T took 5.9 seconds. The L83E via the EN2T took 1.6 seconds. The L83E via it's built in port took 0.4ms.
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Old March 9th, 2018, 10:25 AM   #9
Geospark
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Quote:
Originally Posted by dmroeder
...I did a test a few months ago reading/writing data using it's gigabit port. A combination of ~1100 read/write of a mixed tag data types. The L75 via EN2T took 5.9 seconds. The L83E via the EN2T took 1.6 seconds. The L83E via it's built in port took 0.4ms.
Yeah, the embedded 1 Gb Ethernet ports are exceptionally fast (128k Ethernet packets/sec & 2000 msg/sec). With the ability to now add up to 256 motion drives and a single controller to a high speed 1 Gb network, using the latest Kinetix drives, and a possible 2ms Coarse Update Rate (CUR); motion control can now be implemented using Ethernet comparable to, if not better than, ControlNet. It also supports Safety Functions over the network for drives and motion.

Example prices:

1756-L75
Allen-Bradley LOGIX 5575 PROCESSOR WITH 32MB
List Price: €12,719.00

1756-L85E
Allen-Bradley ControlLogix 5580 Controller 10MB
List Price: €13,732.00

Regards,
George
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Last edited by Geospark; March 9th, 2018 at 10:28 AM.
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Old March 9th, 2018, 10:28 AM   #10
kekrahulik
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Looking to convert a program soon (just bought an L83). I'm really excited about your post - hoping I can gain some significant speed.

Several gotchas to watch out for:

L83 can be version 28. Most others require 29, 30, or 31

If you are converting from an L6x or L7x and use UDT's, you may need to add extra UDT "dummy" members to help "buffer" memory due to 32bit vs 64 bit.

Produce Consume connections - need to match RPI's (haven't read enough yet to fuly understand what I'm saying)

Read this:
http://literature.rockwellautomation...m100_-en-p.pdf

BTW: L8xS safety processors are now available (3/9/18) (version 31 req'd)

Last edited by kekrahulik; March 9th, 2018 at 10:31 AM.
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Old March 9th, 2018, 10:47 AM   #11
RonJohn
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Quote:
Originally Posted by kekrahulik View Post
If you are converting from an L6x or L7x and use UDT's, you may need to add extra UDT "dummy" members to help "buffer" memory due to 32bit vs 64 bit.
Are you saying that LINT is now the atomic data type for L8x processors? If not, I'm missing what you're driving at with the need for dummy members.

Quote:
Originally Posted by kekrahulik View Post
Read this:
http://literature.rockwellautomation...m100_-en-p.pdf

BTW: L8xS safety processors are now available (3/9/18) (version 31 req'd)
Thanks for the link & additional info!

I'm in the process of converting an PLC5 to an L81E. Is it suggested that the L8x 1GB port be used for plant network or I/O network? I've heard differing views.
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Old March 9th, 2018, 11:23 AM   #12
Contr_Conn
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Quote:
Is it suggested that the L8x 1GB port be used for plant network or I/O network?
1GB port is recommended for high speed I/O and required for high speed motion.

Last edited by Contr_Conn; March 9th, 2018 at 11:28 AM.
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Old March 9th, 2018, 11:40 AM   #13
Maxkling
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We just did a bench test not too long ago. Our results were:
L63 - Max scan 30.6
L73 - Max scan 19.26
L83 - Max scan 4.9

Huge improvement. We would have a lot more L8X's if redundancy was available... Anyone have news if it will be this fall?
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Old March 9th, 2018, 12:22 PM   #14
kekrahulik
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RonJohn,

Read page 75 of that document. I didn't read it too closely before (just scanned it yesterday). Sounds like an issue if you use LINTs in a UDT. Sounds like a pre-ver27 to ver27 and up issue

Logix Designer Application Version Requirement
Version 26 or earlier Logix5000™ controllers require all data types to be placed on 4-byte
address boundaries in RAM.
Version 27 or later Logix5000 controllers require 8-byte (64-bit) data types (LINTs) to be
placed on 8-byte address boundaries in RAM.

Last edited by kekrahulik; March 9th, 2018 at 12:26 PM.
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Old March 9th, 2018, 01:07 PM   #15
RonJohn
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Quote:
Originally Posted by kekrahulik View Post
Sounds like an issue if you use LINTs in a UDT. Sounds like a pre-ver27 to ver27 and up issue
I reached the same conclusion as you when I read it. Thanks.

Quote:
Originally Posted by Contr_Conn View Post
1GB port is recommended for high speed I/O and required for high speed motion.
Thanks! We don't have high speed motion applications at our site. No 1GB I/O at this time but will plan to use the L8xE port as some will likely added as we replace our old RIO racks.

My main thought was if there would be greater advantage to 1GB data collection/HMI access. Any known plans for 1GB comm module to replace the 1756-EN2T(R)?

Last edited by RonJohn; March 9th, 2018 at 01:08 PM. Reason: added quote
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