Issues with reading a tag when backplane slot = 1

[JarekCts]

Hi,

I'm a member of software team which is responsible for collecting data from PLCs (we don't have physical access to them).
We already use digital petri library and read a data from devices where backplane slot = 0 and works as expected.
Connection settings are like below:

PaddedEPath connectionPath = new PaddedEPath(new PortSegment(1, new byte[]{(byte) 0}));

GetAttributeListService service = new GetAttributeListService(
                    new PaddedEPath(new LogicalSegment.ClassId(0x01), new LogicalSegment.InstanceId(0x01)),
                    new int[]{4},
                    new int[]{2});

Now we want to connect to new PLC which has backplane slot = 1 and I'm able to connect to this device, but I can't read tags.

I searched through discussions already and did some tests by changing the backplane in PaddedEPath parameter to 1:
PaddedEPath connectionPath = new PaddedEPath(new PortSegment(1, new byte[]{(byte) 1}));

I have also tested when it is empty:

PaddedEPath connectionPath = new PaddedEPath(Collections.emptyList());
PaddedEPath connectionPath = new PaddedEPath(List.of());

However I observe errors like below, depends on which test case I run:

com.digitalpetri.enip.cip.CipResponseException: status=0x04 [path segment error] , additional=[] 
com.digitalpetri.enip.cip.CipResponseException: status=0x01 [connection failure] , additional=[0x0315]
com.digitalpetri.enip.cip.CipResponseException: status=0x08 [service not supported] , additional=[]

I'm almost sure that the PLC is setup correctly, because I'm able to read a tag from it using pycomm3 lib in python with connection path "ip_address/backplane/1".

PLC info I got from ListIdentity when connected:

Protocol version: 1
Revision version: 4.8
Product: 1756-ENBT/A
Product code: 58
Device type: 12
Vendor: 1

I don't have access to EDS files yet.

Any advice welcome,
Thanks,
Jarek

[kevinherron]

Use Wireshark and compare the capture of pycomm3 reading the same data. The PaddedEPath you are constructing for slot 1 looks good to me.

[JarekCts]

Thanks, I've seen this suggestion in the other discussion, however we are not allowed to install and use Wireshark or similar software in the company. That's why I decided to drop a post with details of the settings, hoping there’s a chance you might notice something improperly configured that I may have overlooked.

[kevinherron]

There's not enough context here to help. Maybe if you can provide more of the Java code and the corresponding Python code a comparison can be made that way.