Description:
In STEP 7 a distinction is made between the bit alarm procedure and the alarm numbering procedure.

• Bit alarm procedure
  In the bit alarm procedure the alarms are configured in WinCC, ProTool or WinCC flexible for the HMI. Tags are assigned to these signals. While the process is running the tag values are read out from the PLC at regular intervals. The configured messages are displayed on the HMI according to the values read out.
• Alarm numbering procedure
  In the alarm number procedure events to be reported are assigned message texts when the program is created in STEP 7 and alarm numbers are assigned.
  Alarms numbers and associated message texts are stored in the HMI project when generated.
  In productive mode, when an event to be reported occurs, only the alarm number and time stamp are transmitted from the CPU to the HMI device.
  Then the HMI device displays the alarm number, the time of the event and the associated message text. (The message text is already stored in the HMI device.)

When configuring, a distinction is made here between the following three types of alarm:

• Block-related alarms
• Symbol-related alarms
• User-defined diagnostics alarms

The 3 alarm types of the alarm numbering procedure are described in this entry and references are made to other entries that demonstrate how to configure these alarms. The entry is designed to be a guide for the alarm numbering procedure.

The entry covers the following topics:

• Block-related alarms
• Symbol-related alarms
• User-defined diagnostics alarms
• Quantity structure for the S7-300 CPUs for the alarm numbering procedure
• Quantity structure for the S7-400 CPUs for the alarm numbering procedure

Block-related alarms:
You can configure block-related alarms in STEP 7 for BOOL parameters of the input (I), output (Q), marker (M), data (D) and local data (L) areas. They are triggered by the STEP 7 program synchronously to the program runtime using the system alarm blocks. The block-related alarm is sent to the HMI as soon as the STEP 7 program calls a system alarm block You can also have associated values from the PLC displayed on the HMI along with the block-related alarms.
A sample configuration and a description of how to configured ALARM_D and ALARM_S messages are available

• for ProTool in Entry ID:23872245
• for WinCC flexible in Entry ID: 24013249

More descriptions of how to configure block-related alarms are available in the STEP 7 Help under:

• "Creating block-related alarms (CPU-wide)"
• "Creating block-related alarms (project-wide)"
• "Editing block-related alarms (CPU-wide)"
• "Editing block-related alarms (project-wide)"

The following table describes the system alarm blocks that you can use to display block-related alarms in your program. These system alarm blocks are available in the "Standard Library" in the "System Function Blocks" directory.
 

Name	SFB/ SFC	S7 CPU	Acknowl- edgable	Number of alarm- triggering signals per block	Number of possible associated values	Win CC	WinCC flexible/ ProTool
ALARM_SQ	SFC 17	S7-300/400	yes	1	12 ( max. length of all associated values together: 12 bytes)	yes	yes2)
ALARM_S	SFC 18	S7-300/400	no	1	12 ( max. length of all associated values together: 12 bytes)	yes	yes2)
ALARM_SC	SFC 19	S7-300/400	-	-	-	yes	yes2)
ALARM_DQ	SFC 107	S7-300/4001)	yes	1	12 ( max. length of all associated values together: 12 bytes)	yes	yes2)
ALARM_D	SFC 108	S7-300/4001)	no	1	12 ( max. length of all associated values together: 12 bytes)	yes	yes2)
NOTIFY_8P	SFB 31	only S7-400	no	8	10	yes	no
ALARM	SFB 33	only S7-400	yes	1	10	yes	no
ALARM_8	SFB 34	only S7-400	yes	8	None	yes	no
ALARM_8P	SFB 35	only S7-400	yes	8	10	yes	no
NOTIFY	SFB 36	only S7-400	no	1	10	yes	no

Table 1

¹⁾ The system functions SFC 107 and SFC 108 are supported by S7-300 CPUs from firmware V2.5.0.
²⁾ Whether alarm display is possible depends on the HMI type.
³⁾ Alarm_SC (SFC19) is not an alarm-triggering system function (SFC), but is only for querying the alarm status.

The system alarm blocks in Table 1 can be implemented in the following types of network:

• Industrial Ethernet
• MPI
• PROFIBUS

Symbol-related alarms:
You can configure symbol-related alarms in STEP 7 for BOOL parameters of the input (I), output (Q) and marker (M) areas. Associated values can also be configured for symbol-related alarms. The alarms and associated values can be displayed with WinCC.
You can use the symbol-related alarms on S7-400 CPUs. They are triggered asynchronously to the program runtime. Here you can set a monitoring time (SCAN grid).

Descriptions of how to configure symbol-related alarms in STEP 7 are available in the STEP 7 Help under:

• "Creating symbol-related alarms (CPU-wide)"
• "Creating symbol-related alarms (project-wide)"
• "Editing symbol-related alarms (CPU-wide)"
• "Assigning and editing symbol-related alarms (project-wide)"

User-defined diagnostics alarms:
Via SFC 52 (WR_USMSG) you can enter user-defined alarms and additional information into the CPU's S7 diagnostics buffer. The S7 diagnostics buffer can be displayed on the HMI with WinCC and ProTool. It is not possible to display the S7 diagnostics buffer with SFC 52 in WinCC flexible. You can use other blocks for WinCC flexible. For this please refer to Entry IDs: 22449810 and 22319131.

Descriptions of how to configure user-defined alarms in STEP 7 are available in the STEP 7 Help under:

• "Delete user-defined alarms (CPU-wide)"
• "Delete user-defined alarms (project-wide)"
• "Creating user-defined alarms (CPU-wide)"
• "Creating user-defined alarms (project-wide)"

More information on SFC 52 is available in Table 2 below:
 

Name	SFB/ SFC	S7 CPU	Acknowl- edgable	Number of alarm- triggering signals per block	Number of possible associated values	Win CC	WinCC flexible/ ProTool
WR_USMSG	SFC 52	S7-300/400	-	-	2 pieces of additional information	yes	no/yes 1)2)

Table 2

¹⁾ Display of the S7 diagnostics buffer is not available in WinCC flexible as in ProTool. Refer here to Entry IDs: 22449810 and 22319131.
²⁾ Whether alarm display is possible depends on the HMI type.  

Quantity framework of the S7-300 CPUs for the alarm numbering procedure
With regard to quantity frameworks you must take into account not only the maximum number of alarms possible, but also the number of stations for alarm functions that can be logged on.
With S7-300 you can split the communication connections into PG, OP, S7-Basic communication and stations for alarm functions. The maximum number of communication connections and splitting is determined finally by the number of alarm stations that can be operated.

Table 3 below shows the quantity frameworks of the S7-300 CPUs (with actual firmware, see item 26290163).
 

CPU	Order no.	Max. number of stations that can be logged on	Simultaneously active ALARM_S blocks	Max. number of associated values per alarm
CPU 312C	6ES7312-5BD01-0AB0	6	20	1...12 ( max. length of all associated values together: 12 bytes)
CPU 312C	6ES7312-5BE03-0AB0	6	20
CPU 313C	6ES7313-5BE01-0AB0	8	20
CPU 313C	6ES7313-5BF03-0AB0	8	20
CPU 313C-2DP	6ES7313-6CE01-0AB0	8	20
CPU 313C-2DP	6ES7313-6CF03-0AB0	8	20
CPU 313C-2PtP	6ES7313-6BE01-0AB0	8	20
CPU 313C-2PtP	6ES7313-6BF03-0AB0	8	20
CPU 314C-2DP	6ES7314-6CF02-0AB0	12	40
CPU 314C-2DP	6ES7314-6CG03-0AB0	12	40
CPU 314C-2PtP	6ES7314-6BF02-0AB0	12	40
CPU 314C-2PtP	6ES7314-6BG03-0AB0	12	40
CPU 312	6ES7312-1AD10-0AB0	6	20	1...12 ( max. length of all associated values together: 12 bytes)
CPU 312	6ES7312-1AE13-0AB0	6	20
CPU 312	6ES7312-1AE14-0AB0	6	300
CPU 314	6ES7314-1AF11-0AB0	12	40
CPU 314	6ES7314-1AG13-0AB0	12	40
CPU 314	6ES7314-1AG14-0AB0	12	300
CPU315-2DP	6ES7315-2AG10-0AB0	16	40
CPU 315-2DP	6ES7315-2AH14-0AB0	16	300
CPU 315-2 PN/DP	6ES7315-2EG10-0AB0	16	40
CPU 315-2 PN/DP	6ES7315-2EH13-0AB0	16	40
CPU316-2DP	6ES7316-2AG00-0AB0	12	50
CPU317-2DP	6ES7317-2AJ10-0AB0	32	60
CPU 317-2 PN/DP	6ES7317-2EJ10-0AB0	32	60
CPU 317-2 PN/DP	6ES7317-2EK13-0AB0	32	60
CPU318-2DP	6ES7318-2AJ00-0AB0	16	100
CPU319-3 PN/DP	6ES7318-3EL00-0AB0	32	300
CPU315F-2 DP	6ES7315-6FF01-0AB0	16	40	1...12 ( max. length of all associated values together: 12 bytes)
CPU315F-2 DP	6ES7315-6FF04-0AB0	16	300
CPU315F-2 PN/DP	6ES7315-2FH10-0AB0	16	40
CPU315F-2 PN/DP	6ES7315-2FH13-0AB0	16	40
CPU317F-2 DP	6ES7317-2AJ10-0AB0	32	60
CPU 317F-2 PN/DP	6ES7317-2FK13-0AB0	32	60
CPU 317F-2DP	6ES7317-6FF00-0AB0	32	60
CPU 317F-2DP	6ES7317-6FF03-0AB0	32	60
CPU 319F-3 PN/DP	6ES7318-3FL00-0AB0	32	300

Table 3

Example taking CPU319-3 PN/DP from Table 3:
In CPU319-3 PN/DP (with Firmware 2.7.2 or higher) you can have a maximum of 300 alarms consisting of ALARM_D or ALARM_S blocks. However, more alarms can be programmed/configured.

Quantity framework of the S7-400 CPUs for the alarm numbering procedure
Tables 4 and 5 show the quantity frameworks of the S7-400 CPUs for the alarm numbering procedure.
 

CPU	Number of stations that can be logged on	Simultaneously active ALARM_S/ ALARM_D blocks	Max. number of associated values (additional values) per alarm with ALARM_S/ ALARM_D	ALARM_8 blocks	Max. length of data that can be transferred via SD_i associated values (additional values) per alarm with NOTIFY NOTIFY_8P, ALARM and ALARM_8P per SFB1)
CPU 412-1	8	70	1...12 ( max. length of all associated values together: 12 bytes)	300	432 bytes
CPU 412-2	8	70	1...12 ( max. length of all associated values together: 12 bytes)	300	432 bytes
CPU 414-2	8	100	1...12 ( max. length of all associated values together: 12 bytes)	600	432 bytes
CPU 414-3	8	100	1...12 ( max. length of all associated values together: 12 bytes)	600	432 bytes
CPU 416-2	12	200	1...12 ( max. length of all associated values together: 12 bytes)	1800	432 bytes
CPU 416-3	12	200	1...12 ( max. length of all associated values together: 12 bytes)	1800	432 bytes
CPU 417-4	16	200	1...12 ( max. length of all associated values together: 12 bytes)	10000	432 bytes

Table 4: Block-related alarm functions with S7-400

¹⁾Explanations:
The maximum length of data that can be transferred via the associated values depends on:

• Whether Acknowledgment-triggered Alarms is enabled.
• How many associated values (SD_i) are transferred.
• The maximum length of the data blocks of the CPU used.
• The maximum length of the data blocks of the display devices.

The values in Table 4 are valid

• If Acknowledgment-triggered Alarms is disabled.
• For transferring an associated value (SD_i).
• If the maximum length of the data blocks is 480 bytes for the CPU used and the display devices in each case.

How to calculate the maximum length of the data is explained in the manual "System Software for S7-300/400 System and Standard Functions", section 23.1, in Entry ID 1214574.
 

CPU	Number of stations that can be logged on	Symbol-related alarms (max. number)	Max. number of associated values (additional values) per alarm
CPU 412-x	8	512	1
CPU 414-x	8	512	10
CPU 416-x	12	1024	10
CPU 417-x	12	1024	10

Table 5: Symbol-related alarm functions with S7-400

Explanations for Table 5:
The possible number of symbol-related alarms also depends on the the monitoring time (SCAN grid) set.

Example taking CPU 416-3 to better explain the maximum values given in Tables 4 and 5:

1. You can configure a maximum of 1024 symbol-related alarms for CPU 416-3. All these alarms can be present at the same time.
2. You can program/configure a maximum of 1800 ALARM_8 blocks for CPU 416-3. All these alarms can be present at the same time(1800  * 8 alarms = 14400 alarms).
3. In CPU 416-3 you can have a maximum of 200 alarms consisting of ALARM_D or ALARM_S blocks. However, more alarms can be programmed/configured.

Note:

• Please note that not all these alarms are generally displayed simultaneously on the HMI. How many alarms can be displayed simultaneously on the HMI depends on the quantity structure of your HMI.
• The resources used for ALARM_8 blocks are different to those used for ALARM_S/ALARM_D.