Thermcraft XST-3-0-36-3V - Manual (Page 65)

Operation Installation and Operation Handbook
2408 and 2404 Controller 2-17
ALARMS
Alarm annunciation
Alarms are flashed as messages in the Home display. A new alarm is displayed as a double
flash followed by a pause, old (acknowledged) alarms as a single flash followed by a pause.
If there is more than one alarm condition, the display cycles through all the relevant alarm
messages. Table 2-1 and Table 2-2 list all of the possible alarm messages and their meanings.
Alarm acknowledgement and resetting
Pressing both
and at the same time will acknowledge any new alarms and reset any
latched alarms.
Alarm modes
Alarms will have been set up to operate in one of several modes, either:
• Non-latching, which means that the alarm will reset automatically when the Process
Value is no longer in the alarm condition.
• Latching, which means that the alarm message will continue to flash even if the alarm
condition no longer exists and will only clear when reset.
• Blocking, which means that the alarm will only become active after it has first entered a
safe state on power-up.
Alarm types
There are two types of alarm: Process alarms and Diagnostic alarms.
Process alarms
These warn that there is a problem with the process which the controller is trying to control.
Alarm
Display
What it means
_ FSL* PV Full Scale Low alarm
_ FSH* PV Full Scale High alarm
_ dEv* PV Deviation Band alarm
_ dHi* PV Deviation High alarm
_ dLo* PV Deviation Low alarm
_ LCr* Load Current Low alarm
_ HCr* Load Current High alarm
* In place of the dash, the first character will indicate the alarm number.
Table 2-1 Process alarms
Alarm
Display
What it means
_ FL2* Input 2 Full Scale Low alarm
_ FH2* Input 2 Full Scale High alarm
_ LOP* Working Output Low alarm
_ HOP* Working Output High alarm
_ LSP* Working Setpoint Low alarm
_ HSP* Working Setpoint High alarm
4rAt PV Rate of change alarm
Always assigned to Alarm 4