plc for student

[bleach]

hey every body, i am studying PLC course by using S7-300 and i want a practical example that can be helpful for me to practice for exam cause i don't have any other reference rather than the book. so can u provide me some example that are useful for the student level. pleas.
also i am using a count up counter but when it reach countting to 9 it jump directly to 16 and from 25 to 32 >>>>> what i can do to make it count up 9 10 11 12 etc...
thanks

 

[Steve Bailey]

also i am using a count up counter but when it reach countting to 9 it jump directly to 16 and from 25 to 32 >>>>> what i can do to make it count up 9 10 11 12 etc...

It sounds like your counter is using BCD but whatever you're looking at is interpreting the accumulated value as binary.

From 0 through 9, it doesn't matter whether you interpret the bits as binary or BCD. Either way you get the same number. But the bit pattern for decimal 16, "0000000000010000" is 10 when you interpret it as a BCD number.

 

[bleach]

thanks that mean i will represent 10 by 16 right and so on by using decimal number 1,2,3,4,5,6,7,8,9 A,B,C,D,E,F, 16, 17, etc

 

[Steve Bailey]

It means you have to figure out when the PLC is interpreting a group of bits as a decimal number and when it's interpreting that same group of bits as a BCD or hex number.

 

[bleach]

thanks i got it
thanks for the help

 

[bara_hence]

Or you could use the IEC timers in Siemens where the value of the timer is an ordinary integer..

 

[bleach]

dose this timer exist in simatic manger software
thanx

 

[bara_hence]

Yes they do.. Under library-Standard library-System Function Blocks..