Technical data

Analysis of ACCU 1 and
ACCU 2 on the programmer
Using the online function OUTPUT ISTACK, you can read the
contents of the two accumulators directly out of the ISTACK to find
out the exact cause of the error.
Analysis of ACCU 1 and
ACCU 2 with STEP 5
Since the error identifiers are written to ACCU 1 and ACCU 2
automatically when an error organization block is called, you can take
these identifiers into account when you program your error OB.
This allows you to program specific reactions to various errors in your
organization block depending on the error identifier transferrred to it.
OUTPUT BSTACK online
function
The PG online function OUTPUT BSTACK gives you information in
STOP about the contents of the block stack (BSTACK - see
Section 3.2 "Nesting blocks").
Starting from OB 1 or FB 0, the BSTACK contains a list of all blocks
called in sequence and not completely processed when the CPU went
into the STOP mode. Since the BSTACK is filled from the bottom,
the block on the uppermost level of the BSTACK display contains the
block that was last processed and in which the error occurred.
BSTACK information The top line contains the following information:
Information Meaning
BLOCK NO
Type and number of the block that called the
faulty block
BLOCK ADDR
Absolute start address of the calling block in
the program memory
RETURN ADDR
Absolute address of the first STEP 5 operation
of this block in the user memory.
REL ADDR
Relative address (= difference "RETURN
ADDR - BLOCK ADDR") of the next
operation to be processed in the calling block.
(You can display relative addresses on a
programmer in the mode "disable input"/key
switch and with S5-DOS from Stage IV
upwards using the function key "addresses").
DB NO
Number of the last data block opened in the
calling block
DB ADDR
Absolute start address in the program memory
of the last data block opened in the calling
block (address of data word DW 0)
Error Information
CPU 928B Programming Guide
5 - 8 C79000-B8576-C898-01