Technical data

Integrated Functions (for CPUs with integrated I/Os)
System Software for S7-300/400 System and Standard Functions - Volume 2/2
30-4 A5E00739858-01
30.3 SFB 38 (HSC_A_B)
Description
With SFB 38 (HSC_A_B), you can influence the integrated A/B counter function of
a CPU with integrated inputs/outputs, as follows:
• Specify and adopt the start value
• Specify and set comparison values
• Enable counters
• Enable digital outputs
• Read current counted values and current comparison values
• Query the counted value relative to the comparison value
SFB 38 (HSC_A_B) reads or writes data from the user program in the instance DB
of the integrated function. The A/B counter consists of two counters A and B that
can count simultaneously and are independent of each other (counting up and
down is possible).
The counters function identically; count pulses can be registered up to a frequency
of 10 kHz.
Further Information
The precise meaning of the parameters of SFB 38 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.
Parameters
Parameter Declaration Data Type Memory Area Description
PRES_COMP INPUT DINT I, Q, M, D, L,
constant
New comparison value COMP
EN_COUNT INPUT BOOL I, Q, M, D, L
constant
Enable the counter
EN INPUT BOOL I, Q, M, D, L,
constant
Enable the digital output
SET_COMP INPUT BOOL I, Q, M, D, L,
constant
Set input for comparison value COMP
COUNT OUTPUT DINT I, Q, M, D, L Actual value of the counter
COMP OUTPUT DINT I, Q, M, D, L Current comparison value COMP
ENO OUTPUT BOOL I, Q, M, D, L Error handling:
1 : no error in execution
0 : error in execution