symblolic/absolute

Hi,
in Simatic Manager I can choose if I want that symbolic or absolute programming is prefered(I use german version of Simatic, I don't know exactly how does this option is called in English) With absolute option there is less problems. But if I select symbolic it happens often that the blcoks are not consistent. I mean ie. I work with FC1. Then I add a variable in a global DB. Then I save this DB and when I want to use this variable in FC 1 I cannot do it. What is worse even if I compile FC1 it doesn't help. I have to close FC1 then open it and then once again compile(check consistence). Why does it happens when I work with global DBs?

addressing

if you use absolute addressing, and change an address in the symbols table, say I2.0 to I2.1. this will not get reflected in you r program, the associated tag name will get reflected, but the program addresses will remain the same. However, if you select symbol addressing, and change I2.0 to I2.1, this will be reflected in the program, where ever I2.0 was in your program, will be replaced by I2.1 (symbol remaining the same) because symbol has priority. but you may need to do a consintency check to update all the places the tag is used.

siemen_staines

Step 7 database principle causes this effect. When you change DB structure, accesses to it's fields aren't updated in opened FC. But FC closing and opening are less worse than possible error caused by changing symbol assignment in DB and forgetting about it in FC - because Step doesn't prompt you about it in absolute value priority mode.