Topic: DMD0421
Heap Items
Selecting the Heap Items tab will display a list of the currently defined heap items. This tab has functions that allow you to Add additional heap items, Edit existing heap items, and Delete unused heap items (systems and built-in heap items can not be deleted, only user-created heap items can be deleted).
Total Items shows the number of currently defined heap items and Max Items shows the maximum number of heap items allowed base on the memory capacity of the selected CPU. Checking Hide Built-in Items and the Hide System Items will remove the Built-in and System heap items from the list, leaving only the user-defined heap items in the list.
Adding Additional Heap Items
Clicking Add Heap Item will open the following dialog where you can create a new Heap Item:
Name is the name of the heap item. Heap Items names follow Nickname RulesNicknames can be 1 to 16 characters in length and consist of any combination of alphanumeric characters and underscores ('_', 'a-z', 'A-Z', 0-9), no spaces or punctuation marks are allowed, and must begin with a letter or an underscore.
Data Type is the data type of the heap item:
- Axis Struct heap items are used by the various High-Speed Axis instructions.
- Counter Struct heap items are used by the various Counter instructions.
- Date / Time Struct heap items are used by Date / Time instructions.
- DeviceRef Struct heap items are used by Device Reference.
- Drum Struct heap items are used by DRUM instruction.
- EthernetIOMaster Struct heap item is used by the Ethernet Remote I/O Master.
- FileHandle heap items are by the File System instructions.
- FileSys Struct heap items are use by the RAM and MicroSD card file systems.
- Interrupt Struct heap items are used by Interrupt Service Routine code-blocks.
- IOMaster Struct heap item is used by the Local I/O Master.
- PID Struct heap items are used by PID (Closed Loop Controller) instructions.
- Peerlink Struct heap item is used by the PEERLINK instruction.
- Program Struct heap items are used by Program code-blocks.
- Queue Struct heap items are used by the various FIFO and LIFO queue instructions.
- Rampsoak Struct heap items are used by RAMPSOAK (Ramp / Soak Profile) instructions.
- Server Struct heap items are used by the various communication servers, e.g. EtherNet/IP.
- Stream Struct heap items are used by the Stream-capable instructions (STREAMIN, STREAMOUT).
- String Struct heap items are used by Strings. String Length - (only valid if the Data Type is String) specifies the maximum length of each String in the
block.
- Task Struct heap items are used by Task code-blocks.
- Timer Struct heap items are used by the various Timer instructions.
- <User-Named Struct> heap items are created for each User-defined Data Type.
- Virtual heap items are used by the $LastScan and Subroutine code-blocks.
Is Retentive means heap items marked as retentive will hold their values through a power cycle or a Program-to-Run mode transition. Heap items NOT marked as retentive will be cleared at power up and during a Program-to-Run mode transition. This setting only applies to the data value in the CPU's memory, it does not store of copy the retentive data value in the offline copy of the project. If you ALSO want to store of copy of the data value with the offline project you will need to use the Memory Image Manager to add this heap item to the memory image file that is part of the offline project.
See Also:
Memory View edit and / or monitor the contents of the Memory Blocks and Strings.
Memory Image Manager is used save a copy of the contents of the retentive memory locations and heap items in the offline Do-more Designer project.
Related Topics: