Rockwell Automation 2711 PANELBUILDER SOFTWARE USER MANUAL - Manual (Page 234)

Information and Alarm Windows
Chapter 7
7-26
BCD Data Type
If you specify BCD, the address assignment will be a contiguous string of
either 4, 8, or 12 bits (that is, 1, 2, or 3 digits). For 496 Alarm messages 12
bits are required (4 bits for each of the 3 digits).
Triggering Alarm Messages for Binary or BCD Data Types
To trigger a message, the PLC controller must put a non-zero value which
corresponds to the desired message number, into the designated PLC
address. For example, a “trigger value” of 19 would cause the Alarm
window to appear, displaying message number 19 from the Alarm Message
List. If the trigger value changed to 27, message number 27 would be
added to the list in the Alarm window. Any time the trigger value changes
to any other non-zero value, it is considered a message trigger. Unlike the
Information window function, a trigger value of zero will not make the
Alarm window disappear.
To clear the Alarm window, the operator presses the EXIT button or
acknowledges all alarms. The Alarm window will also be cleared if the
PLC Controlled Clear Window bit is enabled and the bit set to one. PLC
Controlled Clear Window is discussed in the next section of this chapter.
If an invalid (out of range) trigger value is put into the PLC address, the
Alarm window message will be filled with question marks.
Bit Position Data Type for the Alarm window
The address assignment is a contiguous bit string from 1 to 496 bits. Each
bit in the string has a corresponding message number in the alarm message
list. For example, the first bit corresponds to message 1, the second bit
corresponds to message 2, etc. When more than one PLC word is required,
the next higher word number(s) are used. When you specify the number of
bits for this function, you determine the maximum number of messages
that you can trigger for the Alarm window.
IMPORTANT: The Alarm Status screen can only be accessed if the
Alarm Window address is set to Bit data type.