Technical data

Table Of Contents
Integrated Functions (for CPUs with integrated I/Os)
System Software for S7-300/400 System and Standard Functions - Volume 2/2
A5E00739858-01
30-5
30.4 SFB 39 (POS)
Description
With SFB 39 (POS), you can influence the integrated positioning function of a CPU
with integrated inputs/outputs. SFB 39 (POS) provides the following functions:
Synchronization
Execution of the inching mode
Positioning
SFB 39 (POS) for the integrated positioning function reads or writes data from the
user program to the instance DB of the integrated function. The integrated
positioning function acquires signals from asymmetrical 24 V incremental encoders
up to a frequency of 10 kHz. It controls a rapid/creep mode or a frequency
converter via specified integrated outputs of the CPU 314 IFM (controlled
positioning)
Further Information
The precise meaning of the parameters of SFB 39 in conjunction with the
parameters of the integrated function A/B counter and the hardware inputs and
outputs of the CPU is described in detail in the manual S7-300 Programmable
Controller, Integrated Functions CPU 312 IFM/314 IFM.
Parameter
Parameter Declaration Data Type Memory Area Description
EN INPUT BOOL I, Q, M, D, L,
constant
Enable the digital inputs
DEST_VAL INPUT DINT I, Q, M, D, L,
constant
Destination position for the integrated
positioning function
REF_VAL INPUT DINT I, Q, M, D, L,
constant
Reference point for synchronization
SWITCH_OFF_DIFF INPUT WORD I, Q, M, D, L,
constant
Switch-off difference (difference
between the switch-off point and the
destination position) in travel
increments
PRES_COMP INPUT DINT I, Q, M, D, L,
constant
New comparison value COMP
BREAK INPUT BYTE I, Q, M, D, L,
constant
Maximum analog value with which the
traversing movement is controlled
POS_MODE1,
POS_MODE2
INPUT BOOL I, Q, M, D, L,
constant
Start and execute inching mode
POS_STRT INPUT BOOL I, Q, M, D, L,
constant
Start positioning operation on rising
edge
SET_POS INPUT BOOL I, Q, M, D, L,
constant
When there is a rising edge, the value
of the input parameter REF_VAL is
adopted as the new actual value