As I'm sure you read in the Help file, error code 0020h indicates that a minor error occurred.
These are usually things like divide-by-zero or a negative timer preset.
The error will be indicated in one of the bits in the lower half of Status Word S:5.
Unfortunately the MicroLogix controllers can't tell you exactly what File and Rung created the error condition, so you have to trap it programmatically.
There are some good examples of doing this in the RA Knowledgebase, such as in Answer ID 31778 (TechConnect Required).
ML 1100 is connected to a lantronix 485/TCP converter.I checked with removing 485 cable (1763-NC01) then everything working fine.No fault occured in ML 1100 so what will be the issue.before error code was 0020h.