1756-EWEB Open Socket interface

[Contr_Conn]

Here is a private message I got:

I just read a post you contributed to regarding the use of an EWEB module for ASCII string transfers between PLC and PC. You mentioned needing a "Socket Interface", what exactly is this interface and where would I find it ??

I thought this might be interesting for everyone:

With EWEB firmware ver 3.x (currently 3.6) Rockwell introduced an Open Socket interface.

This will let user create own application protocol within Logix program to send and receive data over TCP/IP transport.

As you know currently ControlLogix platform supports only Ethernet/IP protocol based on the open CIP protocol.
If you want to transfer data between Logix and another device then this device must support Ethernet/IP protocol or use 3-rd party protocol converters.

What is a difference between TCP/IP and Ethernet/IP?
TCP/IP is a transport protocol, it just an information delivery level.
Ethernet/IP defines how information should be encoded and decoded - this is an application level.
Ethernet/IP like other protocols uses TCP/IP as a transport level.

Why is it called Open Sockets?
This is a common terminology used with TCP/IP networks with roots going back to BSD UNIX.

Technically open sockets interface can transmit any data string over the Ethernet via TCP/IP.
It is up to receive device to interpret this string and send response if necessary.

What are common applications?
Barcode scanners, RFID scanners, Ethernet Printers.

What else can be done with sockets?
Implement some other common protocols like: Modbus/TCP, FTP etc.

What hardware required?
1756-EWEB module flashed to firmware 3.5 or higher.
It is Logix processor version independent.
1756-ENBT does NOT support sockets.

Reference:

Publication ENET-UM527
http://literature.rockwellautomation.com/idc/groups/literature/documents/um/enet-um527_-en-p.pdf

A131152816 - Sample Application for 1756-EWEB Sockets Feature
http://domino.automation.rockwell.com/applications/kb/RAKB.nsf/0/48CAC6ECFF859DFA8525707E00667C1A?OpenDocument

A133872010 - Using 1756-EWEB Open Sockets with Ethernet Printers

http://domino.automation.rockwell.com/applications/kb/RAKB.nsf/0/09B31A42562E5A9E852570990083C494?OpenDocument

Or call RA techsupport.

 

[UP_Engineer]

EWEB is a lot of work

I've looked into the EWEB card and it seems like just a basic socket interface one can implement in RSLogix 5000. Not?

It looks to me a person has to really understand sockets to make it work. The interface seems very much like the winsock interfaces one finds in Visual C++. The main difference is the instructions are in RSLogix 5000 format. Correct?

In looking at the EWEB documentation, a PLC programmer has to create the socket, then connect to the Ethernet device or accept a connection from the Ethernet device, and then monitor the connection for data and all the time one must be checking for errors and lost connections. That is a tough enough thing to do affectively for an experienced software engineer writing an application in C or C++, but doing it in ladder logic and for PLC programmers not used to such concepts?

Is the EWEB the only solution Rockwell has for handling Ethernet TCP/IP device interfaces?

Does it work for the SLC 5/05 and PLC-5 PLCs?

You mention RFID and Barcode readers. What can the EWEB actually do for RFID and Barcode data besides return the data?

 

[TimWilborne]

Is the EWEB the only solution Rockwell has for handling Ethernet TCP/IP device interfaces?

There are many other solutions but what type of devices are you talking about?

Does it work for the SLC 5/05 and PLC-5 PLCs?

From what I understand, though I have never tried it, the 1746-EWEB will fit in an SLC but the connector will not line up with the SLC backplane so I guess he answer is yes and no for the SLC Too short to fit in a PLC5. Just kidding, I don't think I understand the question

You mention RFID and Barcode readers. What can the EWEB actually do for RFID and Barcode data besides return the data?

I would say all the EWEB is expected to do is send and recieve data. It is a communications device. Conversions are normally handled in the PLC

 

[Contr_Conn]

Edit:

I deleted post, because I just realized who is "up engineer": he registered under new nick and he will be promoting his DeviceMasterUp and blame Rockwell again

... sorry

Just heads up: his old nick was DeviceMaster-Up and he was trying to promote device he sells in every post.

 

[UP_Engineer]

Not the same guy..

Contr_Conn,

In all due respect, you appear to be promoting the Rockwell EWEB card in a major way. Also, you did not answer any of my questions so I am assuming the EWEB is even more limited than I had originally thought.

For your information, I am not DeviceMaster-UP. However, I do know a lot about the DeviceMaster UP. I also know a few things about all the Allen Bradley PLCs including the ControlLogix, SLC, PLC-5, MicroLogix, and CompactLogix PLCs. I know how they all talk Ethernet/IP and a few things about what makes them tick.

I do not blame Rockwell (or Allen Bradley) for anything. They make fine PLCs and their market share reflects that. However, they are not the only company making EtherNet/IP devices and certainly are not the only ones with ideas.

The reason for my post was I'm trying to better understand the EWEB module. We had one in house and it seemed to require a lot of work to handle a single Ethernet device. Perhaps I just did not understand it very well.

Yes, there is new firmware out for the DeviceMaster UP that seems to do some of the same things the EWEB does. I just want to compare the EWEB with it to see how the two devices measure up.

Hope this clears things up a little.

 

[Contr_Conn]

That is exactly why I deleted the original response !

 

[UP_Engineer]

?????

I'm not sure what your point is. First, you advertise the EWEB module and even provide links to the Rockwell documentation. Then you criticize someone who asks you honest questions about it. And somehow I am advertising a different product? I haven't posted any links....

I take it you must know something about the new DeviceMaster UP application and don't want anyone to even mention it - even indirectly? At the same time its OK for you to advertise the EWEB card. So, you work for Rockwell?

Every PLC programmer who looks at the EWEB may have the same questions:
- Does Rockwell have similar support for the CompactLogix, SLC, MicroLogix, and PLC-5 PLCs? (There are about a million or so of those PLCs deployed today.)
- How hard is it to program the EWEB interface?
- How much does one need to know about socket interfaces to use the EWEB?
- How much RSLogix 5000 ladder logic does it take to program an EWEB interface?

As a suggestion, it might be helpful if you got some answers together for these questions. It seems many others may be asking questions too.

I am curious though, is this web site a Rockwell advertising site? I thought this was a site for discussing PLC programming issues. I'm new here so maybe I misunderstood?

 

[TimWilborne]

Actually if you look through the post I am probably the big EWEB pusher and I don't work for Rockwell Automation. I am just pretty familiar with the product and know that it has been a tremendous saving to us. Since it appears I am the 3rd party here or atleast the end user just thought I would mention I have evaluated the DeviceMaster-UP also. Obviously opinions are like you know what but I did not like it.

Does Rockwell have similar support for the CompactLogix, SLC, MicroLogix, and PLC-5 PLCs? (There are about a million or so of those PLCs deployed today.)

I have to guess you mean can you communicate through the EWEB with these devices from a Controllogix since you say you have an EWEB so you must realize it will not fit in the chassis. The answer is a definite yes for all but the PLC-5. The only reason I don't say the PLC-5 is because we do not have any PLC5s at our plant. But the specs say it will communicate fine to it also.

How hard is it to program the EWEB interface?

It is extremely easy. I was strictly a PLC programmer before I used this module and I caught on extremely quick. This is one of the big reasons it like the module. PLC programmers can catch on quickly in an area that usually requires different software training. I can suggest some simple examples on ABs web page if you wish to learn how to use your EWEB module.

How much does one need to know about socket interfaces to use the EWEB?

Absolutely nothing. All I know about them is they are a port that devices or software listen on. It took me about an hour to get the EWEB to print to a printer. The setup is extremely simple. You can find an example of that on ABs website as well.

- How much RSLogix 5000 ladder logic does it take to program an EWEB interface?

2 lines to keep the socket open for further communications. 1 line to connect to the socket, send or receive, and close the socket.

Hope this helps. DeviceMaster UP and the EWEB both have their places. I do not wish to have a debate over which on is better because that would just be an opinion. If I was into debating I could probably fine a political forum to participate in. If you want to learn about the EWEB ask questions and I will try to help

TW

 

[UP_Engineer]

TW,

Thanks much for your thoughtful reply. I apologize if I came across negatively with the other poster. I am new here and don't know who others are on this web board.

I am not looking for a debate either. I am just trying to understand the EWEB module better. I am not trying to advertise the other device. The original post was about the EWEB and I did not bring up the other device on this thread. That was the other poster.

So, if I understand correctly, the EWEB only fits in a ControlLogix chassis, but will communicate to other Allen Bradley PLCs like the SLC and PLC-5 PLCs via EtherNet/IP. That is good to know and may help people.

Example programs help too.

The truth is that one could easily envision a plant with EWEBs and the other device both used throughout and even together at times. Both devices seem to have their strong points.

Thanks again for your thoughtful answers.

 

[ikoe79]

Hi all!

I'm a new for the site...
I have some problem with EWEB module: I have created a simple program to receive data on TCP/IP protocol from HyperTerminal but it doesn't work. HyperTerminal is able to connect to the PLC but as soon as the PLC execute the READ (after an AcceptConnection) it returns with error "Reply data too large". I have followed the istruction from "Ethernet/IP Web Server Module" documentation, in any detail, but nothing.. Can be some error in configuration module? Or maybe, can I connect and send data to(also receive from) Hyperterminal? And about the sample on Rockwell Automation site.. I can't find it.. can someone send it to me? Thankx in advance..

Ikoe

 

[Contr_Conn]

ikoe79:
"Reply data too large" indicates that Destination tag in your message instruction is too small to accept data returned by read.
User manual shows exat structure you should have to make sucsessfull read with buffer at least 480 bytes

 

[monkeyhead]

AB makes some of my favorite hardware, but Eweb annoys me. It may be a great peice of hardware and do all sorts of fantastic stuff, but it boggles my mind that this is the only Allen Bradley hardware solution for doing something as basic as TCP/IP sockets. I fail to see why this ability is worth damn near $2K.

Since Ethernet/IP is already encapsulated inside TCP segments, why can't the the ENET module offer this capability? The code for the TCP/IP stack is already there. It seems like this should be doable with nothing more than a firmware update.

This is directly analagous to only allowing DF1 on serial ports, but not ASCII. Bleh...

 

[ikoe79]

I have tried to resize the buffer (about 1500 bytes) but it doesn't work too (it still shows "Reply data too large" error message).

The strange thing is that, when I tried to connect with a client to the PLC, this makes connection ok but as soon as it executes the READ it returns an error. I attach my project if someone can help me I will be really grateful

 

[ikoe79]

Sorry I have forgotten my project...

 

[Jason Valenzuela]

AB makes some of my favorite hardware, but Eweb annoys me. It may be a great peice of hardware and do all sorts of fantastic stuff, but it boggles my mind that this is the only Allen Bradley hardware solution for doing something as basic as TCP/IP sockets. I fail to see why this ability is worth damn near $2K.

I have no direct experience with that particular module, but I recently completed implementing a 3rd party TCP/IP protocol using Prosoft's MVI-ADMNET module. These modules execute a user program developed in C. I was extremely happy with the development environment and the end result.

Another nice feature is the they make these modules for ControlLogix, CompactLogix, SLC and PLC platforms. In fact the exact same program can run on any of the variations with little or no modification. If you are doing 3rd party network or serial communication, these guys are worth a look.