Diagnosis
ABB Control - AC 31 Page 8-3
1SBC 260400 R1001-b 06.99
The aim of the diagnosis, for the 40 and 50 series central units, is to ensure a rapid and
efficient localization of breakdowns.
1. Types of errors detected
The detected errors are grouped by type into four error classes.
Class 1 errors:
fatal errors
Class 2 errors:
serious errors
Class 3 errors:
light errors
Class 4 errors:
warnings
Access to the Flash EPROM
is no longer assured.
- Flash EPROM checksum
error
The operating system
functions correctly but the
execution of the user program
is not guaranteed.
Detected errors:
- Defective RAM
- Too many timers active
simultaneously
Communication errors.
Stopping the program
depends on the users choice
during configuration
according to the application.
Detected errors:
- Disconnected unit
- Bus error
- NCB / NCBR error
- Cycle time too short
- Addressing fault
Errors occurring on the units
or syntax errors whose effects
will only become apparent
later. The user decides which
actions to initialize according
to the application.
- Internal unit error
- Cut wire
*1
overload, short-
circuit
- Analog output level error
- Defective 10V output
- Program size, program
syntax, sub-program or
interruption program error
- Too many historical values
- All of the units on the bus
are not initialized
*2
*1 error detected if prior configuration by programming with the CS31CO block
*2 error detected if prior software configuration with the "PLC configuration" menu of the Control window.
2. Detection of errors
The detected errors are transmitted to the central unit which signals their presence on the red
ERR led situated on the front of the central unit (see Figure 8-1).
An error on a remote unit is also signaled by the ERR led of the unit concerned.
The SUPPLY led flashes on the extension when an error occurs on the extension.
As soon as the error has been detected and corrected by the user it can be acknowledged:
By restarting the central unit
Through the software
Or by program.
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