Hello [:)]

We use a system PLC with step 5(SIMATIC S5-115U 943CPU) and SCADA system"WINCC 5.2, all Date transfer by DB from PLC to SCADA and from SCADA to PLC,of course, we use different DB. The problem in which form we must send a value from SCADA to read it correctly in PLC, for example, now we need to add some valve must open with % from 0 to 100. When SCADA send in DB a value 50, I can't see the value, i see value 0! Form that use in "WINCC5.2 word real. How I can do to resolve this problem?
And my second question in step 5 can we use multiplication and division:
We receive a Value X from Analog Input 4-20mA (0-65000) and we receive a Value Y From SCADA a value is from 0 to 100 in a word in DB for example
DB5.DW110 & command Open or Close ,then we Must open or close if: TRUE[Y -(X/650) >0] and TRUE [Command Open] Then we Open
TRUE[Y -(X/650) >0] and TRUE [Command Close] Then we Close How do you think, this algorithm can work and how I can do it in step 5? Thank you and hope see your answer soon
My last question ,we have problem with memory M that i use in program , i need more but i all memory bit that we have i use ,what memory can use ,can we use in step5 like this step7 bit in Db ,like that :DB10.DBX1.2 or that not possible in step5 ?

Hello Xeren,

generally, for the operations possible with S5-115 CPU 943 pls. refer to the
"S5-115U Programmable Controller CPU 941/942/943/944 Reference Guide".
You can download it under:
http://support.automation.siemens.com/WW/view/en/1085938/

To question 1: CPU 943 doesn't support floating point double words; preferably use for communication with WinCC integer words as analog values (actual values, setpoints etc.).

To question 2: Basicly, CPU 943 supports only calculations "+" and "-", but not "*" and ":".
Calculations should preferably be done in WinCC, i.e. "Linear scaling" (but this is not a topic for the ***S5*** conference).
As an alternative (note consumption of processing time and memory space!), you may use in CPU 943 the FBs for calculation, as described in
http://support.automation.siemens.com/WW/view/en/16888600.

To question 3: For setting / resetting of a data bit, you can use operations like
*** Set bit ***
A DB a                 call data block
L DW x                 load data word
L KM 00...010...00     load mask
OW                     OR - word
T DW x                 transfer back to data word
*** Reset bit **
A DB a
L DW x
L KM 11...101...11
AW
T DW x
For scanning a data bit, you can also use masks and then compare the word to 0.
*** Scan for "1" ***
A DB a
L DW x
L KM 00...010...00
AW
L KH 0000
>< F
<>
<>
*** Scan for "0" ***
A DB a
L DW x
L KM 00...010...00
AW
L KH 0000
!=F
Or you load the word, shift right and the use conditional jump operations like JP, JN, JM.

Lupus