Issue 5 - September 2006
Page 19 of 65
3.5 Diagnostic
Configuration
The Triguard SC300E Fault Tolerant Safety PLC provides an extremely high level of hardware
fault diagnostics. All diagnostic errors found initiate a change in state in the Fault Register. It is
therefore mandatory that the Fault Call Module be activated in one of the diagnostic networks to
provide access to system level diagnostics.
3.5.1 Diagnostic Message Generation
The activation of the Fault Call when an error is found must be used to provide a diagnostic
maintenance message to the operator, to allow repair actions to be taken. Diagnostic
messages can be provided in a number of acceptable formats, eg Printed Messages, Operator
Alarms, Diagnostic LED Alarms and Diagnostic Alarm Mimics on Operator Stations. A minimum
of one digital output must be configured to give a fail-safe output to ensure that the
operator/maintenance is made aware that there is a problem with the system that needs action.
A combination of methods is usually utilised to provide the maintainer with diagnostic
information and the operator with alarm and status information.
For information on the Triguard error bits refer to the Triguard User Help facility.
3.5.2 Printed
Messages
The triplicated database can contain a number of printed messages that can be triggered by
events such as diagnostic alarms and plant alarms. The printed messages database is
prepared by a Systems Designer linking the discrete, to which the event is to be referenced, to
the alarm diagnostic message to be printed. The message database is compiled and loaded as
part of the load module.
3.5.3 Diagnostic
LED's
As all diagnostic information exists as discretes within the database, these can be utilised to
drive outputs directly to light panel mounted LED's for example. It is also practical to utilise the
Dual Serial Multiplexer System TM117DMX to drive LED's for alarms. The TM117DMX is not
approved for safety critical signals.
3.5.4 Display
System
Diagnostics
In systems that are provided with Operator Workstations for graphical alarm information (such
as TriCommand), diagnostic display mimics can be generated allowing VDU diagnostic alarm
displays of the diagnostic discretes. These operator stations are not normally fault tolerant and
as such are not considered as part of the safety system.
3.5.5 Maintenance
Workstations
The Password Protected Maintenance Workstation is used to display the diagnostic and history
tables in a snapshot manner, it also provides detailed diagnostic information on I/O module and
I/O channel errors. During operation it is not necessary to have the maintenance workstation
continuously attached to an operating Triguard SC300E PLC. When maintenance actions have
been completed the TriBuild Workstation should be disconnected from the operating SC300E
PLC.
3.5.6 Error Flags and Automatic Diagnostic Actions
The diagnostics available through the TriBuild Workstation are extremely comprehensive and
detailed down to channel level. A summary of these diagnostics is made available to the user
by the use of the "Fault Call", which provides a voted set of diagnostic flags.
