Siemens SIMATIC S5-90U System Manual page 257

S5-90U/S5-95U
Table 9-4. Format of the Controller DB (Continued)
Data Word Name
11 STEU
12 YH
14 BGOG
16 BGUG
22 X
24 Z
29 XZ
48 YA
All parameters (with the exception of the control word STEU) must be specified as 16-bit fixed point
numbers.
Caution
!
The PID algorithm uses the data words that are not listed in Table 9-4 as auxiliary flags.
Initialization and Call Up of the PID Controller in a STEP 5 Program
Several different PID controllers can be implemented by calling up OB251 repeatedly. A data block
must be initialized prior to each OB251 call up.
Note
Important controller data are stored in the high-order byte of control word DW11 (DL11).
Therefore make sure that only T DR 11/SU D11.0 to D11.7 or RU D 11.0 to D11.7
operations are used to modify user-specific bits in the control word.
EWA 4NEB 812 6115-02b
Control word (bit pattern)
Value for manual operation (- 2047 to +2047)
Upper limit value (- 2047 to +2047)
Lower limit value (- 2047 to +2047)
Actual value (- 2047 to +2047)
Disturbance variable (- 2047 to +2047)
Derivative time (- 2047 to +2047)
Output variable (- 2047 to +2047)
Integrated Blocks and Their Functions
Comments
9-13