Technical data

Table Of Contents
SFBs for Integrated Control
System Software for S7-300/400 System and Standard Functions - Volume 2/2
A5E00739858-01
27-3
Manipulated Value
The manipulated value can be limited to a selected value using the LMNLIMIT
function. Signaling bits indicate when a limit is exceeded by the input variable.
The LMN_NORM function normalizes the output of LMNLIMIT according to the
following formula:
LMN = (output of LMNLIMIT) * LMN_FAC + LMN_OFF
LMN_FAC has the default 1 and LMN_OFF the default 0.
The manipulated value is also available in the peripheral format. The CPR_OUT
function converts the floating-point value LMN to a peripheral value according to
the following formula:
LMN_PER = LMN
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Feed Forward Control
A disturbance variable can be fed forward at the DISV input.
Initialization
SFB 41 "CONT_C" has an initialization routine that is run through when the input
parameter COM_RST = TRUE is set.
During initialization, the integrator is set internally to the initialization value I_ITVAL.
When it is called in a cyclic interrupt priority class, it then continues to work starting
at this value.
All other outputs are set to their default values.
Error Information
The error output parameter RET_VAL is not used.