7/15/2012 1:47 PM | |
Joined: 9/27/2006 Last visit: 8/14/2024 Posts: 12277 Rating:
|
Hello Manmeet; The OB3x are cyclic interrupts that can be set at specific scan times; this is called the "run sequence" of the program blocks (CFC, SFC charts). By default OB35 is available in all S7 CPUs and it is set at 100 ms (adjustable by the user). The S7-400H have at least 4 different OB3x, the S7-417H has all of them (max 8), to spread the CFC blocks in different calling sources with different cycles. Using OB1 with PCS 7 is not recommended as its cycle is not set at a specific and verifiable value, which is required for the determionistic calling of the CFC blocks. You can find a lot more information in the various PCS 7 manuals, such as: SIMATIC Process Control System PCS 7 Engineering System (V8.0) 8.12.3.6 Runtime Properties of the Blocks Introduction This section describes some of the basics required to understand the runtime properties of blocks.Runtime propertiesThe runtime properties of a block decide how the block is included in the run sequence within the entire structure of the CPU. These properties are decisive for the response of the target system in terms of reaction times, dead times, or the stability of time-dependent structures, for example, closed loops.The runtime properties of the blocks have default settings but these can be adapted individually for each block.When it is inserted, each block is assigned default runtime properties. It is therefore installed in a run sequence in a task (OB). The tasks form the interface between the operating system of the CPU and the S7 program. Blocks can also be installed in runtime groups that are themselves installed in tasks (OBs).NoteWhen you create new chart, a runtime group is created automatically in which all the blocks of this chart will be installed. SIMATIC Process Control System PCS 7 CFC for SIMATIC S7 (V8.0) Chart installation pointer Each program contains its own global "chart installation pointer". This pointer determines the following: · The task into which the runtime group of the chart created next is to be inserted · The position at which the runtime group of the chart created next is to be inserted, or after which block at the task level. If the task does not yet contain a runtime group, this position is "empty". The pointer refers to the actual task. This pointer is customized only in the runtime editor (not in the CFC Editor). OB 35 is the default chart installation pointer. |
Last edited by: dchartier at: 7/15/2012 1:48 PM |
|
This contribution was helpful to
5 thankful Users |
7/17/2012 10:39 AM | |
Joined: 3/14/2008 Last visit: 8/13/2024 Posts: 2084 Rating:
|
Note that for the CEMAT library, almost all blocks are inserted into OB1, one of the exceptions. |
If I could help you, you can use the RATE button. Thank you. |
|
This contribution was helpful to
1 thankful Users |
Follow us on