Micro820 Ethernet - Some Structured variables return 'Path Destination Unknown'

[glasiuta]

Hello. I am new to the Advanced HMI product, and want to say thank you and very nice work! I am very impressed and excited of the possibilities. Developing several Micro820's and am hoping to use AdvHMI for FAT testing.

I have the EthernetIPForMicro800 driver setup and talking fine. I created a global Variable (HMI) with a custom Structured data type called 'OPC_Test' with 5 members of different data types (Real, DINT, INT, BOOL, and String). The values all display correct on an analog value display using the PLCAddress format:

HMI.Real_Test, HMI.Bool_Test, etc...

In my program, I have another global variable (LIT101) with custom structured data type containing members of different types that contain data relating to the LIT101 device. When I address the analog value display LIT.Value, AdvHMI keeps returning 'Path Destination Unknown'.

I've attached a couple of screenshots as that better describes the setup. If more information is required, please let me know, and any help or insight is greatly appreciated. Thank you in advance.

[Archie]

The Path Destination Unknown is an error that comes directly from the PLC. It generally means the tag does not exist. Double check your tag names, even copy and paste it from the programming software and into AdvancedHMI. When I have doubt, I go online with the PLC and browse to the tag, then copy the name directly from there.

[glasiuta]

Hi Archie, thanks for the reply. Good to know that the error is PLC generated.

100%, the tag name is correct, I've pasted it directly from the online database in CCW. I still receive the same error. I've attached a screenshot of my online database.

I know that CCW is still limited in certain functionality, and I had wondered if my structured data type had too many elements, but I am able to poll data from another custom structure with just as many elements. Are there any other parameters in the analog display properties tab relating to the PLC or address, element size, etc that I may have to adjust?

Thanks.

[Archie]

To my knowledge there are no limitations or restrictions to prevent this from reading. I won't have access to a Micro820 for testing until Tuesday when I get back to the office. Would it be possible for you to do a Wireshark capture?

[Godra]

By the time Archie is to have access to his Micro820 and you getting the WireShark capture, would you also consider trying different things, like:

1) Post a picture of your other custom structure that you've successfully polled
2) Your initial post shows LIT.Value and your picture shows LIT101.Value and the top of the picture also shows LIT_101 as variable. Have you tried all these different combinations one at the time?
3) Have you tried polling any other value from the picture?

For all the testing you can try using BasicLabel instead of AnalogDisplay.

[glasiuta]

Hi Godra. Thank you for the suggestions and keen eye.
I hadn't noticed before I uploaded the same screenshot twice, and mistakenly typed LIT.Value rather than LIT101.Value. The 'LIT_Test_Value' tag was a global I created for a seperate test, but yes, I was able to poll it successfully as well.

One attached screenshot shows the tag 'HMI' I've successfully polled with custom structure type 'OPC_Test', and the second screenshot shows the structure of the unsuccessful tag 'LIT101' with structure 'AICombined_AddOn'

Perhaps an important item to note that I had not considered is that the 'LIT101' variable I am unable to poll has a custom structure that was created by the User Defined Function Block I built, rather than through the Data Type menu. this might be the problem unfortunately, even though the program shouldn't care where it was created, as the variable itself (LIT101) is global, and all the member data (.Value, etc...) should be global as well.

In RSLogix 5K, the program automatically creates the UDT when you create and Add On instruction, so I had assumed CCW acts in the same way, perhaps I am wrong? I'm at a remote office today so won't have access to my shop, but I can experiment with this over the weekend.

Thanks again for the suggestions.

[glasiuta]

Archie, I didn't have a chance to do a Wireshark data capture due to another project taking me away, but I did some tests.

It appears that we are unable to poll data in the Micro PLC that exists in a structure created from a UDF (User Defined Function) instance. For example, I have a UDF to handle our analogs called "AI_Combined_AddOn", which gets assigned a tag, LIT101 in this case. The LIT101 tag is created as data type 'AI_Combined_AddOn' with all of the data members that exist in the UDF parameters (LIT101.Value, LIT101.HHAlarm, etc...)

This limitation is applicable when attempting to poll this data from a ControlLogix as well. I'm in contact with Rockwell to hopefully improve some of these limitations in future firmware updates.

Thanks for the help, I look forward to working with this software!

[Archie]

Thanks for the update. The Micro800 seems to be quite limited with using CIP symbolic addressing. So far, these are limitations I have found:

- Early versions of firmware did not support symbolic addressing at all
- Only Global variables can be read
- Multi-service request doesn't work which can make refreshing a lot of values very slow

and now adding to the list:

- Variables in UDFs not accessible