CtrlLgx L8x vs L7x

Hello All,
I am looking at specifying a new Control Logix project and was wondering if I could get some feedback on the new Rockwell Automation L8x series of processors vs the L7x series of processors. It looks to me that it is a no brainer as the L8x comes with a built in Enet port which on a small system would save a slot by not having to put in a separate Enet module.
If anyone has any thoughts or experience with these processors I would appreciate the feedback.
Thanks!
blawrenz

I had one at my desk to tinker around with but I was mostly testing Ethernet performance. I've never seen the pricing but I was told that they are priced similar to buying a L7x and an Ethernet module. But as you mentioned, you save a slot.

When they say that Ethernet performance is significantly faster, they are not kidding, though I'm not sure how often it is truly required. Since they are quad core, communications gets a dedicated core, which eliminates the "system overhead time slice" configuration.

Just to get an idea of the Ethernet performance, I had a L83E and a L75 with a EN2T. I made ~1100 reads/writes via python, it took the L75 5.9 seconds, the L83E was 0.42 seconds.

I checked the list pricing on an L71 vs an L81e and the list price cost difference is $80. Seems to me that it is probably a no brainer.

Only caveats are that the L8's do not support redundancy and they are not listed in Rockwell's Integrated Architecture Builder (IAB) software for use in a PAx system so I don't know if they are officially recommended for PAx applications.

Cost is about $200 more for an L8 which would certainly be offset if you dont have to purchase an Ethernet card.

Remrun said:

Only caveats are that the L8's do not support redundancy and they are not listed in Rockwell's Integrated Architecture Builder (IAB) software for use in a PAx system so I don't know if they are officially recommended for PAx applications.

Click to expand...

Along those lines, it should also be noted that L8's do not support Sercos or "Analog" servo control (using the 1756-M02AE module). While this is not an issue for new builds it could be an issue for upgrades.

For instance we have a client with a system running and L61, the L61 failed and we were looking into what to recommend as an upgrade (the panelview was a PV+ 700 via DF1) so we were thinking of the L8 because he wouldn't need an Ethernet card, but that was when we discovered that the L8's do not support "Analog" servo control so we had to go with an L71 and an Ethernet card.

Price Comparison: 1756-L8 vs 1756-L7
https://theautomationblog.com/price-comparison-1756-l8-vs-1756-l7/
The article is about 2yrs old...