Power Automation System(PAS) -V

  • Function of Task For SICAM PAS
  • Task

Function Tasks do not need to be configured in SICAM PAS SoftPLC. A task already exists, which considerably simplifies

configuration. Every time SoftPLC is called up, all POUs programmed in the SoftPLC are computed.

The call-up of a task is event-controlled. The following events are possible:

  1. New incoming indication/measured value/metered value
  2. New command/command acknowledgement
  3. Interlock request (The central distribution component of the SICAM PAS – DSI Server requests whether a command is interlocked; interlocks are specified via the SoftPLC.)
  4. Timer countdown.
  • POU
  1. In SICAM PAS, PAS firmware blocks do not have a number which specifies the task sequence.
  2. The task sequence depends on the arrangement of the blocks: As a rule, a POU is processed from top to bottom and from left to right.
  • Selecting and inserting a PAS firmware block
  1. After creating a new CFC program, click on the POUs tab in the Catalog.
  2. Under Firmware, select the block which you want to insert. Next, drag and drop the block into the editor

window.

As soon as possible operator  release the mouse button, the mouse pointer changes its shape depending on the possible

plug-in positions.

  1. If the mouse pointer shows a prohibition sign, you cannot insert the block.
  2. If the mouse pointer shows Insert, you can click to insert the block.
  • Interconnecting PAS interface tags
  1. In order to ensure that the CFC program can send/receive information to/from SICAM PAS, you must interconnect the program with PAS interface tags.
  2. The tags describe the items of information mapped in the Mapping view of SICAM PAS UI – Configuration or by the SoftPLC.

The PAS firmware blocks are interconnected by means of the connectors in the right-hand and left-hand margin bars in the editor window:

  1. In the Catalog, click on the Tags tab. The tags available in the project are shown.
  2. Select one or several tags to be interconnected via a margin bar. Be aware of the interconnection options of tag in PAS interface protocol.
  • Margin bars in the editor window with CFC program

The right-hand & left-hand margin bars in the editor window with CFC program provide different functions.

Operator following functions can be selected from the left-hand margin bar:

  1. Commands to the SoftPLC
  2. Incoming indications, metered values and measured values to be processed

The right-hand margin bar provides the following functions:

  1. Outgoing commands (command derivation, switching sequence)
  2. Indications generated by the SoftPLC
  • Connecting a block

CFC block is connected with other blocks by means of the right-hand and left-hand margin bar.

For example, a group indication is performed with PAS_ORI.

  1. Interconnect a PAS interface tag representing an indication with a connector in the left-hand margin bar.
  2. Interconnect an input of the PAS_ORI block via the left-hand margin bar:

In this case, select the input of the block & It’s corresponding connector with the PAS interface tag in the left-hand margin bar.

In the SICAM PAS SoftPLC UI, left click on Insert & go to Insert Connection. The input  block is interconnected with the connector in the margin bar.

  1. The output is connected in a similar way, but you connect the output to a group indication in the right-hand margin bar.
  • Inserting text blocks

To write into blocks, you can insert text blocks in the CFC program.Right-click on the editor window of the CFC program and select Insert Text Block in the context menu.

The mouse pointer shape is changes depending on the possible plug-in positions:

  1. If the mouse pointer shows a prohibition sign, you cannot insert the text block.
  2. If the mouse pointer shows Insert, you can click to insert the text block.

Enter the text desire in the input text & then press the ENTER key. The text block is shown in gray (disabled).

In order to be able to edit the text in the text block diagram, double-click the block diagram.

  • Inserting a block in the chart

Proceed as follows to insert another block:

 After you have opened the CFC program in the SICAM PAS SoftPLC UI, click on the POUs tab in the Catalog.

Under Firmware, select the PAS_COMMCP block. Next, drag and drop the block into the editor window.

As soon as possible operator release the left mouse button, the changes mouse pointer its shape depending on the possible plug-in positions.

  1. If the mouse pointer shows a prohibition sign, you cannot insert the block.
  2. If the mouse pointer shows Insert, you can click to insert the block.
  • Interconnecting a block

A connector is connected in the left-hand margin bar with a PAS interface tag representing a command.

  1. Select the IN input of the PAS_SELC block.
  2. Select the related connector with the PAS interface tag in the left-hand margin bar.

In the SICAM PAS SoftPLC UI, left click on Insert buttom & go to Insert Connection. The IN input of the block is

  1. interconnected with the connector in the margin bar.
  • Initializing SICAM PAS firmware blocks

All SICAM PAS firmware blocks (beginning name with PAS_) which create an indication, a timer or a command

must be initialized during the first computing cycle of the resource. When using CFC, this initialization is automatically performed , since all blocks are compulsorily computed during every computing cycle & thus also during the first cycle.

A corresponding block instance without parameters is sufficient in most cases. However, it is safer to call up the instance block with those parameters which are also used after the first cycle in order to programming on timer, a command or an indication. However, it is performed without actually creating the timer, the command or the indication upon initialization.

In the Editor of  SFC, the 1st step (initialization step) should be used for this purpose, since this 1st step is always run during the first cycle. However, this is not a prerequisite for STL & ST.

If a SICAM PAS firmware block is called up in STL or ST code without conditions & the POE is not exited by

a statement return, no explicit initialization is required.

If  however, a firmware block  of SICAM PAS is called up via one single condition (that is IF statement, CASE statement, loop statement), after that it is not ensured that the condition is already met during the 1st  computing cycle. In this case, the instance should be initialized at the beginning of the POE.

  • POUs and Tasks in the SICAM PAS SoftPLC
  • POUs

In SICAM PAS SoftPLC UI, all three POU types based on IEC 61131-3 are available for code generation (POU

is the abbreviation for Program Organization Unit).

Since all types have advantages and disadvantages and since many programmers only generated program

POUs in the past due to a lack of knowledge, the use of these types is briefly described in this section. The

following applies for types of all POU: POUs must not be called up recursively, That  means  they must not call up themselves.

  • Functions

The simplest POUs are referred to as ‘functions’. As a rule, they are used for less complex and frequently occurring logic. The Functions have no memory (i. e. local tags are not saved beyond the call function ). They always have a return value & any number of input parameters. Since they have no function, So it’s function  always usually provide the same result with the same input connection.

Functions can’t be used for the direct processing of PAS information, but only for the processing of IEC 61131-3 data types protocol. The function code is not copied, but only referenced from other POUs (functions, function blocks or programs). If the code of a frequently used, the logic function is changed  for all POUs which

perform calls also changes. Functions can only be generated with the ST and STL programming languages.

Examples for functions:

  1. simple arithmetic operations (adder, multiplier)
  2. simple logic operations (logic AND, logic OR)
  3. simple conversion functions (conversion of a UPF time stamp into an online readable time stamp)
  • Function blocks

Function blocks are particularly important for POUs which are often underestimated. The logic can have any degree

of complexity. Function blocks can have any number of inputs & outputs, can access global tags & it’s are suitable for reuse scenarios in the SICAM PAS SoftPLC.

Function blocks are particularly useful for identical logics, frequently used,. Contrary to functions, they have a

memory. The function block of local tags  instance are not lost after the call. For the next call, they are available

with the values defined last. Usually Functions are always provide the same result with the same input connection.

This type of rule does not apply for function blocks, since their result can depend on saved information.

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