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Summary of TD Bit Usage

BitsAssociated

with anAlarm*

Enable Conditionfor the Bit

Result shown onthe TD Display

Clear Condition for the Bit

1 ALARMENABLE

The alarm must be enabledwith the TD_ALRMinstruction using theAlarmSymbolic Name as theinstruction input.

When an alarm is enabled and the TDdefault display mode is set to the alarmmode, the alarm message is placed onthe TD display. If there are multiplealarms enabled, the one or two highestpriority alarms are displayed.

If an alarm requires useracknowledgment, the message will flash(blink) until it is acknowledged by the user.The alarm MUST be acknowledged beforeother alarms can be viewed. An alarmthat requires acknowledgement will not bereplaced on the display by higher priorityalarms until the alarm is acknowledged.

If the alarm contains editable variablesthe user can edit or accept the values (by

pressing the ENTER key). If the edits arenot completed, and the alarm messagerequired acknowledgement, the messagewill again begin to flash.If the user screens are set as the defaultdisplay mode for the TD and an alarm isenabled, an alarm indicator will begin toflash on the TD display. The indicator islarge if there is an alarm enabled thatrequires acknowledgement. The indicatorwill be small if the alarms do not requireacknowledgement. The user can switchto the alarm display to view the alarms.The alarms will be presented to the user

in priority order.

There are different ways to clearthe alarm enable bit:

1) If an alarm requiredacknowledgement, the TD willclear the alarm enable at thesame time that the Alarm

Acknowledgement bit is set inthe CPU.

2) If an alarm contains editablevariables, the TD will clear thealarm enable bit when all of theedits are completed and the lasteditable variable in themessages is written to the CPU.

3) The PLC program logic may

clear the alarm enable bit at anytime. This will remove the alarmmessage from the TD display.

An alarm message will not beremoved from the display if theuser is editing a variable in themessage or if the message hasnot yet been acknowledged.

(4) If the message does notrequire acknowledgementand/or does not contain editablevariables, then the CPUprogram logic MUST clear thealarm enable bit.

2 ALARMACKNOW-LEDGE

Alarm acknowledgement isavailable only if the wizardconfiguration has the optionenabled for this alarm:Alarm should requireoperatoracknowledgement

The user acknowledges an alarmmessage by scrolling to the message anpressing the ENTER key. The TD willthen set the acknowledge notification bit inthe CPU and the alarm message will stopflashing (blinking).

If there are no editable variables in themessage the TD will also clear the alarmenable bit for this message.

If there are editable variables in the

message, the user must either edit thevariables (change them and pressENTER) or accept the current values(press ENTER). When the last variable inthe message is edited or accepted, theTD will write the variable to the CPU andclear the alarm enable bit.

If the user does not complete editing thevariables in the message, the TD willbegin to flash (blink) the message to notifythe user that an action is still pending.

The TD will set the alarmacknowledge bit. The userprogram logic must clear thealarm acknowledgement bit.

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3 ALARMMESSAGE:EMBEDDEDVARIABLEEDITNOTIFICA-TION

The edit notification isavailable only when thealarm contains a variableand the user has enabledthe Wizard option to allowediting of the variable.Operator is allowed to editthis data.

If the alarm messagecontains multiple editablevariables, each variablehas a unique editnotification bit.

The TD will write the updated variablevalue to the CPU and set the editnotification bit for that variable when theoperator presses the ENTER key,completing the edit of the variable.

The user program can monitorthe edit notification bit torecognize when an editablevalue has beenchanged by the operator. Theuser program can then takesome action based on the newvalue for the variable.

The user program must clearthe edit notification bit so thatsubsequent edits can berecognized.

4 USERSCREENEMBEDDEDVARIABLEEDITNOTIFICA-TION

The edit notification isavailable only when theuser screen contains avariable and the user hasenabled the Wizard optionto allow editing of thevariable. Operator isallowed to edit this data.

If the user screen containsmultiple editable variables,each variable has a uniqueedit notification bit.

The TD will write the updated variablevalue to the CPU and set the editnotification bit for that variable when theoperator presses the ENTER key,completing the edit of the variable.

The user program can monitorthe edit notification bit torecognize when an editablevalue has beenchanged by the operator. Theuser program can then takesome action based on the newvalue for the variable.

The user program must clearthe edit notification bit so thatsubsequent edits can berecognized.

* The TD 200 Wizard settings for each alarm message determine which bits are available for that message.