STARTUP / TROUBLESHOOTING
5-8
Hardware and Installation User Manual
5.2.3
Troubleshooting with Status Words
In addition to the auxiliary functions described above, the TI525/TI535 PLCs
provides operational information in the form of status words. These status
words can be read with the programming device. Status words may also be
contained within an RLL program so that diagnostics can be executed during
run-time conditions.
5.2.3.1
Status Word One (STW01)
STW01 provides information in the word format shown in Figure 5-2. STW01
shows the status (good or failed) of the PLC battery, scan overrun,
communication port, I/O modules, indirect table move overflow, and special
function modules. A bit containing a 0 indicates no error, while a 1 indicates a
problem or failure.
STW01
Bit
1
2
3
4
5
6
7
8
9 10
11 12 13 14 15 16
Not used
1 = battery low
or off
1 = scan overrun
i.e., fixed
scan time is
too short to
run RLL
program
1 = communication
port failure
1 = I/O failure *
1 = indirect table
move overflow
1 = intelligent
module com–
munication
failure
Spare
*This applies to any I/O module capable of diagnosing its own failure.
MSB
LSB
This bit is also set if there is an I/O mismatch, i.e., the I/O configuration
does not agree with the installed module for any I/O slot in the system.
Figure 5-2
Format of Status Word One (STW01)
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