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"Unable to read block" errors after ControlLogix v30 firmware upgrade


Last Update: 11/12/2018
Problem:
After upgrading a ControlLogix device to firmware version 30, KEPServerEX reports errors when trying to read Boolean arrays from the device for several pre-defined structures.

Cause:
The version 30 firmware upgrade changes Boolean arrays of tags in several pre-defined structures to a single Long tag. This means the address and type for those tags are now incorrect.
For example, a tag utilizing the SFC_STOP pre-defined structure has a 32-bit array of Boolean tags named Status before upgrading to firmware version 30. After upgrading the device to firmware version 30, there is only one Long tag named Status.

Solution:
The bits in the new Long tag for each affected pre-defined structure can be accessed using the .bit notation. For example, to get the first bit of the Status tag for a SFC_STOP tag group, enter the address as SFC_STOP.Status.0 as type Boolean.

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