AVEVA™ Communication Drivers

Alarms and events

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Alarms and events

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Last UpdatedDec 11, 2025
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Alarm and event information can be received from the S7-300 and S7-400 PLCs. The item syntax for Alarms and Events is as follows:

ALARM<EV_ID>.<Extension 1>[,<Extension 2>[<Suffix>]]

EVENT<EV_ID>.<Extension 1>[,<Extension 2>[<Suffix>]]

Note: The S7-1200 and S7-1500 PLCs do not provide alarms and events capability.

The following table shows valid values and valid value combinations for Extension 1, Extension 2, and Suffix.

Item:ALARM<EV_ID>

Extension 1	Extension 2	Suffix	Data Type	Range
EVENT_ STATE			VT_UI2	0 to 65535
STATE			VT_UI2	0 to 65535
ACK_STATE			VT_UI2	0 to 65535
TIME_ STAMP			VT_BSTR	String, ***
NO_ADD_ VALUES			VT_UI2	0 to 10
ADD_VALUEw	DATA_TYPE		VT_BSTR	String
	LENGTH		VT_UI2	0 to 65535
	Xx.y		VT_BOOL	0 or 1
	Sx,v STRINGx,v		VT_BSTR VT_BSTR	String String
	Bx BYTEx	DT	VT_UI1 VT_UI1 VT_BSTR	0 to 255 0 to 255 String
	Bx,v BYTEx,v		VT_ARRAY\|VT_UI1 VT_ARRAY\|VT_UI1	0 to 255 for each element 0 to 255 for each element
	CHARx	DT	VT_I1 VT_BSTR	-128 to 127 String
	CHARx,v		VT_ARRAY\|VT_I1	-128 to 127 for each element**
	Wn WORDn	BCD KT S5T D	VT_UI2 VT_UI2 VT_UI2 VT_BSTR VT_BSTR VT_BSTR	0 to 65535 0 to 65535 0 to 9999 0.0 to 999.3 0ms to 2h46m30s0ms String
	Wn,v WORDn,v		VT_ARRAY\|VT_UI2 VT_ARRAY\|VT_UI2	0 to 65535 for each element 0 to 65535 for each element
	INTn	BCD D	VT_I2 VT_I2 VT_BSTR	-32768 to 32767 0 to 9999 String
	INTn,v		VT_ARRAY\|VT_I2	-32768 to 32767 for each element**
	Dm DWORDm	BCD T TOD	VT_UI4 VT_UI4 VT_UI4 VT_BSTR VT_BSTR	0 to 4294967295* 0 to 4294967295* 0 to 99999999 String String
	Dm,v DWORDm,v		VT_ARRAY\|VT_UI4 VT_ARRAY\|VT_UI4	0 to 4294967295 for each element 0 to 4294967295 for each element
	DINTm DINTm,v	BCD T TOD	VT_I4 VT_I4 VT_BSTR VT_BSTR VT_ARRAY\|VT_I4	-2147483648 to 2147483647 0 to 99999999 String String -2147483648 to 2147483647 for each element**
	REALm		VT_R4	+/-1.2e-38 to +/-3.4e+38
	REALm,v		VT_ARRAY\|VT_R4	+/-1.2e-38 to +/-3.4e+38 for each element**

Item:ALARM<EV_ID>

Extension 1	Extension 2	Suffix	Data Type	Range
EVENT_ STATE			VT_UI2	0 to 65535
STATE			VT_UI2	0 to 65535
ACK_STATE			VT_UI2	0 to 65535
TIME_ STAMP			VT_BSTR	String, ***
NO_ADD_ VALUES			VT_UI2	0 to 10
ADD_VALUEw	DATA_TYPE		VT_BSTR	String
	LENGTH		VT_UI2	0 to 65535
	Xx.y		VT_BOOL	0 or 1
	Sx,v STRINGx,v		VT_BSTR VT_BSTR	String String
	Bx BYTEx	DT	VT_UI1 VT_UI1 VT_BSTR	0 to 255 0 to 255 String
	Bx,v BYTEx,v		VT_ARRAY\|VT_UI1 VT_ARRAY\|VT_UI1	0 to 255 for each element 0 to 255 for each element
	CHARx	DT	VT_I1 VT_BSTR	-128 to 127 String
	CHARx,v		VT_ARRAY\|VT_I1	-128 to 127 for each element**
	Wn WORDn	BCD KT S5T D	VT_UI2 VT_UI2 VT_UI2 VT_BSTR VT_BSTR VT_BSTR	0 to 65535 0 to 65535 0 to 9999 0.0 to 999.3 0ms to 2h46m30s0ms String
	Wn,v WORDn,v		VT_ARRAY\|VT_UI2 VT_ARRAY\|VT_UI2	0 to 65535 for each element 0 to 65535 for each element
	INTn	BCD D	VT_I2 VT_I2 VT_BSTR	-32768 to 32767 0 to 9999 String
	INTn,v		VT_ARRAY\|VT_I2	-32768 to 32767 for each element**
	Dm DWORDm	BCD T TOD	VT_UI4 VT_UI4 VT_UI4 VT_BSTR VT_BSTR	0 to 4294967295* 0 to 4294967295* 0 to 99999999 String String
	Dm,v DWORDm,v		VT_ARRAY\|VT_UI4 VT_ARRAY\|VT_UI4	0 to 4294967295 for each element 0 to 4294967295 for each element
	DINTm DINTm,v	BCD T TOD	VT_I4 VT_I4 VT_BSTR VT_BSTR VT_ARRAY\|VT_I4	-2147483648 to 2147483647 0 to 99999999 String String -2147483648 to 2147483647 for each element**
	REALm		VT_R4	+/-1.2e-38 to +/-3.4e+38
	REALm,v		VT_ARRAY\|VT_R4	+/-1.2e-38 to +/-3.4e+38 for each element**

*: Starting with version 1.1, this string value can be used to timestamp other alarm items.

**: For DDE/SuiteLink, the item value is the Hex ASCIi representation of the complete array. The result is one string containing all the elements of the array in the Hex ASCIi representation of the binary data in big-endian format when data is returned to the DDE/SuiteLink layer.

***: For DDE/SuiteLink, this value is restricted to the range of 0 to 2147483647. Values higher than that are clamped to the maximum value of 2147483647 in a SuiteLink or DDE client. In this case, the quality of the item shows "Clamp High."

****: For alarm blocks (such as SFB31, 34, 35) that provide multiple event states in one notification, the timestamp that comes with the notification reflects only the timestamp of the last changing state. This restriction is prescribed by the message that it receives from the PLC.

Where:

<EV_ID>	is the ID defined by Step7, in the integer format, filled with leading zeros up to six (6) characters.
x	is the start address, with a range from 0 to 65535.
y	is the bit position, with a range from 0 to 7. 0 is the LSB (Least Significant Bit). 7 is the MSB (Most Significant Bit).
n	is the start address of 2-byte data/2-byte data arrays, with a range from 0 to 65534.
m	is the start address of 4-byte data/4-byte data arrays, with a range from 0 to 65532.
v	is the length of data in elements (an item in an array), with a range from 1 to (net PDU data size/type size - header information).
w	is the length of the net S7 string-data in characters, with a range from 1 to 10.

Note: All alarms and events are Read-Only. The longest string or array that can be read in a cyclic service is the length of the PDU size minus 32 bytes. The longest string the InTouch software can process is 131 bytes. The SIDirect Communication Driver does not process writes (POKES) to Alarms and Events.

Examples:

ALARM000010.TIME_STAMP

EVENT001234.ADD_VALUE2,LENGTH

ALARM000555.ADD_VALUE10,REAL0

EVENT000001.ADD_VALUE3,D0TOD

Alarm and event information is delivered from the S7-300/400 PLCs in the form of data items with the syntax described above. Alarm provider and alarm acknowledgment functionality is not supported.

The configuration of the alarms is first performed in the appropriate function blocks in the S7-300/400 PLCs as follows:

Name	SFB/SFC	S7 CPU
ALARM_SQ	SFC 17	S7-300/400
ALARM_S	SFC 18	S7-300/400
ALARM_DQ	SFC 107	S7-300/400
ALARM_D	SFC 108	S7-300/400
NOTIFY_8P	SFB 31	S7-400
ALARM	SFB 33	S7-400
ALARM_8	SFB 34	S7-400
ALARM_8P	SFB 35	S7-400
NOTIFY	SFB 36	S7-400

Events must be configured in the Symbol Editor.

AVEVA™ Communication Drivers

Alarms and events

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Alarms and events

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