NI Ethernet/IP as adaptor using explicit messaging from ControlLogix PLC

Question

I am successfully using a ControlLogix PLC with an implicit i/o connection to a NI9792 WSN Gateway. This I/O connection only communicates control and status of the program on the 9792, however there is a bunch of data (500 bytes) that is collected every few hours that I would like to get from the 9792 with an explicit message using a couple of assemblies. How do I need to set up the MSG instruction in Logix to get this data from the 9792? According to references it should be Service 0x0e, Class 0x04, Instance n, Attribute 0x03 but this gives me an error on the PLC MSG instruction. I have tried a variety of things to get this working but have had no luck, the implicit I/O connection works fine, but the explicit connection return an error code of 0x0005 'Class or instance not supported'. I have tried a couple different assemblies and get the same result. I can however change the MSG instruction to get the identity of the NI driver (Service 0x01, Class 0x01, Instance 1, Attribute 0x00) and this works fine so I know the MSG function is working with the correct path and destination element.
In the first attachment, the bottom while loop contains the assembly I'm trying to access via the explicit MSG, the top loop is the implicit I/O connection which works fine.
The second attachment is my ControlLogix MSG instruction configuration with the error shown.
Thanks,
Dave
David Gaylord
Controls Engineer
Alcoa Howmet Research Center
Attachments:
screenshot.1.jpg ‏323 KB
screenshot.3.jpg ‏95 KB

Answer 1

Sorry about that, I think I had too many things going on here at the same time.  I agree that the Create Assembly Instances is working as an adaptor.  Perhaps my terminology is incorrect by calling the other a scanner, it was my impression that by giving it a IP address to communicate with that it was a scanner, as it was making the request for data or setting the data in a remote device.  Either way, I would prefer to keep the system as a simple adaptor so the setup of these systems is easier on our customers.
I do see one VI in the example that i forgot about, the Remove Assembly Instance, I'll add that to my vi and see what happens, though I doubt that will cure my problem.  I've seen on the forums that there is a limit to the amount of about 500 bytes per assembly but is there maybe a limit to the amount of assemblies or total bytes used by the EIP toolkit? 
David Gaylord
Controls Engineer
Alcoa Howmet Research Center