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
30-3
30.2 SFB 30 (FREQ_MES)
Description
With SFB 30 "FREQ_MES" (frequency meter), you can influence the integrated
frequency meter function of a CPU with integrated I/Os, as follows:
Select and set comparison values.
Output the measured frequency.
Read the current comparison values.
Query the relationship of the measured frequency to the comparison value.
Further Information
The meaning of the individual parameters of SFB 30 in conjunction with the
parameters for the integrated frequency meter function and the hardware inputs
and outputs of the CPU is described in detail in the S7-300 Programmable
Controller, Integrated Functions manual.
Parameters
Parameter Declaration Data Type Memory Area Description
PRES_U_LIMIT INPUT DINT I, Q, M, D, L,
constant
New (upper) comparison value
U_LIMIT
PRES_L_LIMIT INPUT DINT I, Q, M, D, L,
constant
New (lower) comparison value
L_LIMIT
SET_U_LIMIT INPUT BOOL I, Q, M, D, L,
constant
Set input for new comparison
value U_LIMIT
SET_L_LIMIT INPUT BOOL I, Q, M, D, L,
constant
Set input for new comparison
value L_LIMIT
FREQ OUTPUT DINT I, Q, M, D, L Measured frequency in MHz
U_LIMIT OUTPUT DINT I, Q, M, D, L Current comparison value
(upper limit)
L_LIMIT OUTPUT DINT I, Q, M, D, L Current comparison value (lower
limit)
STATUS_U OUTPUT BOOL I, Q, M, D, L Status bit
"1": FREQ > U_LIMIT
"0": FREQ
U_LIMIT
STATUS_L OUTPUT BOOL I, Q, M, D, L Status bit
"1": FREQ < L_LIMIT
"0": FREQ
U_LIMIT