Chapter 6 CPU Functions
6- 10
6.7 Diagnosis of External Device
This flag is provided for a user to diagnose any fault of external device and, in turn, execute halt or warning of
the system. Use of this flag displays faults of external device without any complicated program prepared and
monitors fault location without any specific device (XG5000 and etc) or source program.
(1) Detection and classification of faults in external device
(a) The trouble (fault) of external device may be detected by user program and largely divided, depending
on the type, into error and warning; the former requires halt of PLC operation and the latter simply
displays the status while PLC keeps working.
(b) „Error‟ uses „F202 (_ANC_ERR)‟ and „Warning‟ uses „F203 (_ANC_WB) flag‟.
(c) As the detection request flag, ‟Error‟ uses „F2002 (_CHK_ANC_ERR) flag‟ while „Warning‟ uses
„F2003 (_CHK_ANC_WB) flag‟.
(2) Troubleshooting external device
(a) When detecting any trouble of external device in user program, it writes a value except „0‟ by classifying
the type, which is defined by a user in „F202 (_ANC_ERR)‟ while the detection request flag checks it at
the time when the program ends with „F2002 (_CHK_ANC_ERR) On, and PLC outputs based on the
“Emergency Output” setting in I/O parameter, making it as the same error status as detected by PLC
itself.
(b) If any trouble occurs, a user may identify the cause by using XG5000 and alternatively by monitoring
„F202 (_ANC_ERR) flag‟.
Example
(c) If any trouble occurs, CPU is in error status and operation halts. At this moment, F2020 and F2002 flags
are off (error LED switches on and off every second.)
(3) Processing warning of external device
(a) When detecting any warning of external device in user program, it turns on a flag in the warning
position of system flag „F203 (_ANC_WB) and if turning on the detection request flag, „F2003
(_CHK_ANC_WB)‟ , it displays warning at the time when scan program ends. If a warning occurs, the
detection request flag, „F2003 (_CHK_ANC_WB)‟ is automatically off (F203 is not deleted).
(b) If a warning occurs, the LED switches on and off every other second.
(c) If turning off a bit in question of F203 and turning on F2003 bit after processing warning, warning is
cancelled and the LED turns off.
Example
Error detection request On
Warning detection request On
Warning detection request On
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