Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual - Manual (Page 91)

Error Reporting
Chapter 7
7Ć2
To aid in error monitoring, the 1775–KA module maintains a 6–word
error block in the module status area of PLC–3 memory. This error block
contains the following information:
Word 0 – error code for the last error that occurred in the current
message procedure
Word 1 – total number of errors that occurred in the current message
procedure
Word 2 – always contains the value 1
Word 3 – line number where the error occurred in the highest level
(nest level 1) message procedure
Word 4 – line number where the error occurred in the next highest level
(nest level 2) message procedure
Word 5 – line number where the error occurred in the lowest level (nest
level 3) message procedure
The error codes reported are those listed in Appendix B.
The line number is the relative location of a command line from the
beginning of the message procedure containing the line. The first line of
each procedure is line number 1, and any following lines are numbered in
ascending sequence. Nested procedures begin with line 1 again, thus the
need for words 3, 4, and 5 in the error block.
You do not enter the line numbers for a procedure; the 1775–KA module
automatically keeps track of the line numbers for you. The line numbers
do not appear in a listing of the message procedure, but they are recorded
internally by the module.
Error Block Operation
Figure 7.1 illustrates how the error block works. In this figure, an
addressing error (invalid destination address) occurs in procedure SUB2,
which is nested 3 levels deep. Word 5 of the error block gives the line
number where the error occurred in procedure SUB2. Word 4 gives the
number of the line in procedure SUB1 that executed procedure SUB2.
Error Monitoring