Installation manual

Publication 1747-RM001G-EN-P - November 2008
SLC Status File B-41
S:20
and
S:21
Status Test - Fault/Powerdown - Rung/File
These registers indicate the executable rung (word S:20)
and file (word S:21) number that the processor last executed
before a major error or powerdown occurred. To enable this
feature, you must select the Test Single Step option at the
time you save your program. You can use these registers to
pinpoint the execution point of the processor at the last
powerdown or fault routine entry. This function is also
active in the REM Run mode. See S:2/4.
Application example: Suppose your program contains
several TON instructions. TON T4:6 in file 2, rung 25
occasionally obtains a negative preset. Recovery from the
negative preset fault is possible by placing the preset at 100
and resetting the timer.
Place the following rung in your fault routine to accomplish
this. Bit B3/0 is latched as evidence that an application
recovery has been initiated.
••••
This feature is built into the SLC 5/03 and higher processors.
Selection is not required.
•••
Table B.4 Status File Functions (Continued)
Address Classification Description Fixed
5/01
5/02 5/03 5/04 5/05
MOV
MOVE
Source 100
Dest T4:6.PRE
EQU
EQUAL
Source A S:6
Source B 52
(RET)
(RES)
T4:6
(L)
B3
0
(U)
S:1
13
EQU
EQUAL
Source A S:20
Source B 25
EQU
EQUAL
Source A S:21
Source B 2
The value 52 equals
0034 Hex. This is the
error code for a
negative timer preset.
Rung
Number
File Number