1756-EWEB question

[FSEIPEL]

I'm new to the Allen Bradley PLC's, I want to add webserver capability to view tags from the rest of plant, but wanted to know if:
1.) 1756-EWEB can go in any chassis or just the one CPU is located in? Manual seemed to indicate CPU chassis only, but I wasn't sure if that was the case even if chassis have Ethernet 1756-ENBT cards in them already?
2.) If NO to 1, can 1756-EWEB replace the ENBT card & handle communications to slave racks? EWEB would go to a switch. Currently ENBT's go to a switch.

I'd rather not move existing cards around to achieve webserver functionality. There are free slots in 'slave' racks but not in main CPU rack/chassis.

 

[Donnchadh]

Hi

I have only ever set it up in the rack with the CPU but I have set up all other types of cards in remote racks. You could add into your remote rack in the project tree in your project and see does it allow you to add it.
I know this is not a full test but it's a start. If you were to add into your remote rack I THINK it will work but I would also say it would not fault your connection so you could try it but may be wait till it will not affect the plant just incase
Donnchadh

 

[Contr_Conn]

1. Dataview and data access is limited to the local rack only. You can do limited bridged CIP messaging.

2. EWEB can't control any I/O, so you can't replace ENBT with EWEB

 

[Ken Roach]

Yes, the 1756-EWEB can read and write tags in ControlLogix and CompactLogix controllers that are not in the same chassis. They can only communicate over EtherNet/IP and ControlNet.

There is a good RA Knowledgebase document that supplements the User Manual with this information. It's KB Article ID # 34644 (TechConnect Required).

Edit: if Control_Conn calls it "limited", then I defer to his evaluation. He knows the -EWEB better than anyone.

The 1756-EWEB trades I/O scanning functionality for Webserver functionality, so it cannot replace the 1756-ENBT modules.

It still allows non-IO functions like HMI access, MSG instruction support, and online monitoring using RSLogix 5000.

The 1756-EWEB is a fairly "mature" technology, as it's based on a three-generations-old hardware platform and really hasn't been worked on since 2008 or so. Nothing wrong with that if it gives you the performance and packaging you want.

Most web-browser-based HMI are PC-based. The Red Lion DataStation Plus is nice for browser access to a hardware device, but the browser-based HMI has the same resolution as a G306, so it's often disappointing when you bring it up in a browser window.

 

[FSEIPEL]

Chassis Question

Thanks much to all for the wonderful tips. I've used the Red Lion devices before (actually, their Honeywell 'rebranded' HMI for the HC900 & their re-branded version of Crimson). So I'm somewhat familiar with them. I had the same issue with resolution. It does support a custom web page feature & with javascript you can even include advanced plotting like 'dygraph' to let you easily select tag(s) to plot, zoom & pan, etc from the CSV files. So if you use the 'custom' web pages, you can produce different resolutions, but that is painful since you can't use Crimson. I looked at the Datamaster but ultimately decided against it, mainly due to it not integrating as cleanly with A/B, though it does have Logix drivers. Most of my experience has been DeltaV DCS & I'm just learning RSLOGIX/RSVIEW so please bear with me.

I think 1756-EWEB is a good choice for us as for now, I just want basic no-frills display of the data. Unfortunately, I have NO tech connect, is there any other way to get that document?

I'm somewhat confused by the conflicting answers on this. It sounds like, from the last message, maybe I *can* put it in the slave rack, IF I use ReadLogixTag function but the simpler data views would clearly NOT be supported? I'm fine just using ReadLogixTag functions IF that will work. This function uses a CIP path so I assume it's CIP messaging? I'm completely comfortable opening Notepad and ftp'ing some pages with ReadLogixTag functions in them to achieve the objective but I'd rather NOT move cards between racks (i.e. move an I/O card from CPU chassis to slave chassis to make room for EWEB module). I wasn't planning on using the basic dataviews anyway. So now that I've framed the question better, does ReadLogixTag work if 1756-EWEB is on a remote rack, or is that deemed 'CIP messaging'? I wasn't clear if ONLY the MSG function was CIP messaging...

On one of the two PLC's, the master & slave rack communicate over Ethernet; the second PLC has 4 racks or so, and they communicate with Controlnet, except for master rack/chassis on second independent PLC, I believe it has Ethernet. I'm not looking to communicate vast amounts of data here, just read some tank levels & flow rates on office computer desktops & perhaps handheld devices.

 

[FSEIPEL]

CIP Paths

I wanted to post an update in case anyone else ever has issues with this: I was able to get a hold of the KBA from our consultant, it clearly indicates ReadLogixTag will do what I want. I should have ordered only ONE Web+ card to talk to both PLC's, Allen Bradley's literature on how to determine CIP path is not all in one place, the relevant table for CIP path in ReadLogix tag is in http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1756-rm003_-en-p.pdf on pp 181 -- General Instructions Reference Manual.