EIP Addressing Array of Structs

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Joined: Fri Oct 13, 2017 5:02 pm

EIP Addressing Array of Structs

Post by chood » Fri May 24, 2019 9:40 pm

I have an array I am reading from a 1756 L71 AB PLC.

Structure in PLC is an array of "Steps" that hold 9 fields per element with varying data types (ints and strings).

When trying to addressing each element in OA, i am creating the following a structure for each step and appending the step number to the structure name.
NextStep (int)
PresetTime (int)
Description (string)

The addressing looks as follows: PLC1.A3.Steps[0].NextStep. This works fine for a single element, however, when I add the second element of the array, I receive an error from OA:

WCCOAeip (1), 2019.05.24 14:24:04.536, SYS, WARNING, 54, Unexpected state, EipMaster, processLogixResponse, PLC11: Read of tag[0] A3.Steps[0].NextStep failed with error CIP Error 0x00ff: General Error

I looked up the General error 0x00ff and found that it could pertain to any of the following:
Address out of range
Attempt to access beyond end of data object
Data in use
Data type is invalid or not supported

However, I don't quite understand where the issue lies. OA is the only system polling the device, the address is valid and the data type matches.

Any input on this would be appreciated.

Posts: 110
Joined: Tue Jan 15, 2019 2:12 pm

Re: EIP Addressing Array of Structs

Post by gschijndel » Wed Sep 11, 2019 7:18 am

3.16 P013 contains a fix for UDT arrays.

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