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Entry type: FAQ Entry ID: 92190378, Entry date: 05/12/2014

What should you watch out for when setting or changing archiving parameters in SIMATIC powerrate (blocks PRE_SUM, PR3_SUM; Parameters: ARSNO_C, ARSNO_S, ARSNO_V)?

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Parameterization of function blocks (general)
Function blocks are parameterized at their call interface. Furthermore the function blocks have an instance data block (I-DB). In addition to static program variables the parameterization at the call interface is also stored in this I-DB. There are two distinct cases:

  • An interface parameter is not given a value when the FB is called.
    The parameter concerned in the I-DB has the initial value set by the programmer in the FB (0, for example).
  • The value of an interface parameter is subsequently deleted.
    In this case, the last value set at the parameter is stored in the I-DB. If this is not wanted, but would rather use the initial value (0, for example), then you must reload the I-DB into the CPU for initialization or set the parameter with the relevant value (0, for example).

Parameterization of the ARSNO_C, ARSNO_S and ARSNO_V parameters at the PRE_SUM or PR3_SUM capture block
This concerns the parameterization and use of the ARSNO_C, ARSNO_S and ARSNO_V parameters at the PRE_SUM or PR3_SUM block. If this parameter has an archiving ID, the associated calculated value of PRE_SUM or PR3_SUM is archived under that ID.

If the parameter is not switched, the initial value of the parameter is 0 (zero). This corresponds to disabling the archiving of the this parameter.
Accordingly, there is no disabling if the value originally switched is subsequently "simply" deleted. The associated I-DB must be initialized in addition (as described before).
To avoid this step, it is recommended to explicitly set the value 0 (zero) for disabling.

Changes in SIMATIC powerrate V4.0 SP2 Update 1
When you install SIMATIC powerrate, a sample powerrate project is installed in STEP 7. This includes a sample configuration and parameterization of a powerrate system.

The parameterization of sample measuring points on PRE_SUM/PR3_SUM at the ARSNO_C, ARSNO_S and ARSNO_V parameters was changed with SIMATIC powerrate V4.0 SP2 upd1 in compliance with the above-mentioned recommendation (see next screenshot).
Disabling of the archiving is now done in the sample project by explicitly setting the value 0 (zero), for example. Beforehand, the parameters in the sample project were implicitly disabled in the case of non-switching by the initial value (= zero) stored in the instance data block (I-DB).
This change simplifies the visibility and legibility of the parameterization. This does not affect the block behavior.

Fig. 01

Further Information

Topic Entry ID / Link
SIMATIC HMI powerrate V4
SIMATIC powerrate V4.0 SP2 Update 1
Overview of the topic of energy management in Online Support 68043160

Additional Keywords
Energy management, FB1061, FB161, Energy consumption, Energy value, Time interval, Cyclic buffer, Measured value acquisition

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