Siemens Simatic S7-200 CPU 210 System Manual page 118

Special Memory (SM)
SMW2: Analog Adjustment
SMW2 stores the digital value that represents the position of the analog adjustment
potentiometer. You access this value as a word.
The CPU 210 samples the analog adjustment potentiometer at least three times a second
and has a range of integers from 0 to 255. The new value of the analog adjustment
potentiometer is written to SMW2 at the beginning of the next scan.
The analog adjustment potentiometer on the PDS 210 has a nominal range of integers from
0 to 255, with a guaranteed range of 10 to 200.
Table B-2
SM Word
SMW2
SMW4 through SMW20: Reserved
SMW4 through SMW20 are reserved for future use.
SMW22 to SMW26: Scan Times (only for the PDS 210)
SMW22 to SMW26 are available only through communications with the PDS 210. As
described in Table B-3, SMW22, SMW24, and SMW26 provide scan time information:
minimum scan time, maximum scan time, and last scan time in milliseconds.
Table B-3
SM Word
SMW22
SMW24
SMW26
B-2
Special Memory Word SMW2
This word stores the value entered with the analog adjustment potentiometer. This
value is updated once per scan.
Special Memory Words SMW22 to SMW26
This word provides the scan time of the last scan.
This word provides the minimum scan time recorded since entering the RUN mode.
This word provides the maximum scan time recorded since entering the RUN mode.
Description
Description
S7-200 Programmable Controller, CPU 210
C79000-G7076-C235-01