Siemens Industry Online Support
Siemens AG
Entry type: FAQ Entry ID: 109751485, Entry date: 01/10/2018

Why can you not load the project data into the load memory of the S7-1500 CPU when the number of alarms and messages is too large?

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Downloading of the project data to the S7-1500 CPU is aborted if the maximum number of configurable program alarms in your STEP 7 (TIA Portal) project is exceeded.

If the number of configurable program alarms in the hardware configuration exceeds the maximum limit of the corresponding type of the S7-1500 CPU , downloading is not executed. In this case, an error message is displayed In STEP 7 (TIA Portal): "There is insufficient memory on the CPU for this amount of data".

If you download alarm text changes in RUN to the CPU, the changes are downloaded first and only then are the objects to be replaced deleted on the CPU. The number of programmed alarms of the hardware configuration and the alarms already on the CPU must not exceed the corresponding limit of the programmable alarms.

You should reduce the number of alarm and message instances in your S7 station, or use a larger S7-1500 CPU for your project.

The maximum number of alarm and message instances is given in the technical data sheet of each CPU. Under "S7 message functions" you will see the maximum number of configurable program alarms that you are allowed to configure for your S7-1500 CPU.

Fig. 1 shows you an excerpt of the technical data sheet of the S7-1513 CPU.

Fig. 1

Proceed as follows to determine the number of alarm instances in your project:

  1. In the project navigation you double-click "PLC Supervisions & Alarms".
  2. Then switch to the "Alarms" tab.
  3. Under "Program alarms" you mark one alarm type after the other to see the corresponding alarm instance in the "Alarm instances" window. The lines of the alarm instances are numbered which makes doing the math simpler.
  4. Add up the alarm instances of each separate alarm type. The total number of configurable program alarms must not exceed the specification given in the technical data sheet of each CPU.

To find the instances in the STEP 7 (TIA Portal) program you right-click the alarm instance and in the in pop-up menu you select the function "Go to function block".

Fig. 2

Creation Environment
The screens in this FAQ response were created with STEP 7 (TIA Portal) V14 SP1.

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