Specific use is as follows:
1, the general background data block is automatically generated variables, whether they can be changed or deleted depending on how the program is written, if the program is not used can be deleted, can be added on the basis of the original definition of variables.
2, belonging to the background data block as the FB block of the background data block, use on the line function interface signal We have to be flexible according to the specific machine tools and requirements Siemens contains too many things.
3, the first to create a DB block, in this data block to build a real array (array length shall not be less than the number of data), and then the series of data (REAL) into this array; as for the extraction of computing directly read the array value on the line.
4, the data block is equivalent to other variables address, access is divided into direct and indirect addressing. In the creation of db block, if necessary, you can insert the built.
5, sometimes need to create more than one data block, but the structure of the data block, data type are the same, but can not be saved in the same data block.?
6, need to create their own, if you can not use the user data type, you can not bother with this UDT. this time you can first build a UDT, through the UDT and then create the rest of several blocks.