Help me with a preset time value ?

[Lare]

Of course, without DB-blocks PLC can't write data values of program blocks anywhere and PLC will go stop mode.

 

[KAMEL ELSAYED]

thank you very much lare,

finally it's worked
really i am happy

at last i want to thank everyone replied on me

I'm sorry if you feel bored of my questions i am still learning

 

[Lare]

No problem. Siemens isn't easiest PLC to start with. Siemens PLC programg consist of several small parts, which you have to download separatly to PLC. (DB, OB, FB, FC blocks and hardware config)
On other PLC platforms these all are in one place, and changes are downloaded at one time.

It have cons ans pros. Usually you need to compare offline and online blocks to see if all changes are donwloaded to Siemens PLC. Red fault light is easy to get on

Also on Siemens you can download PLC program which have error to PLC and it shows error only after download.
On other PLC platforms it is usually not possible, because program is checked before downloading to PLC.

 

[KAMEL ELSAYED]

hi lare,

i have to start with siemens plc because it Is widespread in Egypt
thank you for the above information

best regards

 

[mk42]

No problem. Siemens isn't easiest PLC to start with. Siemens PLC programg consist of several small parts, which you have to download separatly to PLC. (DB, OB, FB, FC blocks and hardware config)
On other PLC platforms these all are in one place, and changes are downloaded at one time.

It have cons ans pros. Usually you need to compare offline and online blocks to see if all changes are donwloaded to Siemens PLC. Red fault light is easy to get on

Also on Siemens you can download PLC program which have error to PLC and it shows error only after download.
On other PLC platforms it is usually not possible, because program is checked before downloading to PLC.

I will note that the newer TIA Portal software makes a lot of those things easier. It compiles the program before downloading, to try to prevent most syntax errors. It also downloads the whole program, making it far harder to only download part of it on accident.