Message Setup? Allen Bradley Contol Logix

pater01 · Sep 7, 2005

I have a Control Logix controler and I have a Compact Logix controler that are connected thru ethernet. I have never setup messaging to these type of controlers, but I will attempt it
very soon. If you have done this before and can give me some directions, I would very much appreciate it.

Ken Roach · Sep 7, 2005

You can use ordinary MSG instructions, or you can configure "Produced/Consumed Tags" that are exchanged automatically at I/O speeds on EtherNet/IP local networks.

In the MSG instruction, ControlLogix tags are used as the Source and Destination fields, unlike memory register addresses in SLC's and PLC's. Also, the only timeouts are dependent on CIP Connection failures, so you might want to configure your own timeout timer that sets the *.TO bit manually.

Look in the Help file about configuring the Path field. You're going to need to figure out how a CompactLogix considers it's controller to be in a slot (it's 0 or 1, I don't recall right now), and of course you're going to need to know what Slot the ControlLogix controller is in.

The Instruction Set Reference book is very helpful in the use and configuration of MSG instructions.

pater01 · Sep 7, 2005

Messaging with control logix/compact logix

Thank you for the information, I will probably have more questions tomorrow night. This is challenge, and I will need some help to get
this resolved. Thanks again

Contr_Conn · Sep 8, 2005

Message Path for CLX to Compact will be:

1, <ENBT SLOT>, 2, <Compact IP>, 1, 0

Use "CIP Data Table Read" or "CIP Data Table Write" message type
Program MSG in one PLC only
Do not put Ethernet modules in I/O configuration!!

pater01 · Sep 8, 2005

Control Logix to Compact Logix communications.

Today I went to work on the messaging and I think I understand how to configure and set it up. Where I'm getting bogged down is this,
Do I need to do a write message from the control logics to the compact logics? and a read message at the compact logics. The control logics controller has data that I need in the compact logixs in order to complete the functions of the two pieces of equipment. This is my first messaging that I have had to do with
these type of controllers over ethernet. Your help would be very much appreciated.

Operaghost · Sep 8, 2005

The message only needs to be written in one controller.

So you can use a CIP Data Table Write style MSG in the ControlLogix to write to the CompactLogix

or

You can program a CIP Data Table Read style MSG in the CompactLogix to go get the data from the ControlLogix. Typically a Read makes troubleshooting easier.

OG

Contr_Conn · Sep 8, 2005

Operaghost said:
Typically a Read makes troubleshooting easier.

I don't see why, but READ actually takes twice longer and uses 4 packets instead of just 2 for a WRITE.

READ:
Request ->
DATA <-
Rec ACK ->
ACK <-

Write:
Data ->
ACK <-

Contr_Conn · Sep 8, 2005

pater01 said:
This is my first messaging that I have had to do with these type of controllers over ethernet.

In addition you need to make sure both controllers are on the same subnet

pater01 · Sep 8, 2005

From what you are saying is that I could do a CIP read in the compact logics and get the data that I need to do the control of this machine.
I will not have to do a message write from the control logics. Is this correct?

Contr_Conn · Sep 8, 2005

pater01 said:
From what you are saying is that I could do a CIP read in the compact logics and get the data that I need to do the control of this machine.
I will not have to do a message write from the control logics. Is this correct?

Yes,
You need one message only:
in Compact Read message OR in CLX Write Message

Operaghost · Sep 9, 2005

Contr_Conn said:
I don't see why, but READ actually takes twice longer and uses 4 packets instead of just 2 for a WRITE.

ACK <-

I believe a READ takes longer because it is actually a request to write. So you send a READ style message and then the other controller has to write it to you. So writes will be faster transfers but harder when it comes to troubleshooting.

But it should be reiterated for our original questioner that a READ or a WRITE still only require one MSG instruction be programmed.

OG

akreel · Sep 9, 2005

Contr_Conn said:
1, <ENBT SLOT>, 2, <Compact IP>, 1, 0

I don't think you need the first "1".

akreel · Sep 9, 2005

Contr_Conn said:
Do not put Ethernet modules in I/O configuration!!

That's interesting. Why not?

Contr_Conn · Sep 9, 2005

akreel said:
That's interesting. Why not?

I/O configuration is for Inputs and Outputs only,
Communication modules have no business to be in I/O configuration unless they involved in I/O control

G19423 - Yellow Triangles - Cannot establish Connection to Module
G73555394 - General Contrologix guidelines for 1756 Communication modules in I/O configuration tree.

akreel said:

I don't think you need the first "1".

Click to expand...

Message path <port>, <address>
1 (-backplane port), <slot number>

A18446539 - Brief summary to clarify message instruction CIP paths and pathing

mellis · Sep 9, 2005

akreel said:
I don't think you need the first "1".

Akreel,

What usually happens is you type the path as Contr_Conn has shown, and as soon as you accept it, RSLogix replaces the first two elements with the Name of the ethernet card in the I/O config. This is confusing because it looks like you have an odd number of parameters when they should be in pairs.

One more reason to NOT put the ethernet card in the I/O config if it's not being used for I/O. If you don't give it a name, RSLogix can't substitute in your path.

Message Setup? Allen Bradley Contol Logix

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