3.17.15
Generic up-down counter UDFCNT
3.17.15.1
Function block
Figure 112: Function block
3.17.15.2
Functionality
The generic up-down counter function UDFCNT counts up or down for each positive
edge of the corresponding inputs. The counter value output can be reset to zero or
preset to some other value if required.
The function provides up-count and down-count status outputs, which specify the
relation of the counter value to a loaded preset value and to zero respectively.
3.17.15.3
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of UDFCNT can be described with a module diagram. All the modules
in the diagram are explained in the next sections.
Figure 113: Functional module diagram
Up-down counter
Each rising edge of the
UP_CNT
input increments the counter value
CNT_VAL
by one
and each rising edge of the
DOWN_CNT
input decrements the
CNT_VAL
by one. If
there is a rising edge at both the inputs
UP_CNT
and
DOWN_CNT
, the counter value
CNT_VAL
is unchanged. The
CNT_VAL
is available in the monitored data view.
The counter value
CNT_VAL
is stored in a nonvolatile memory. The range of the
counter is 0...+2147483647. The count of
CNT_VAL
saturates at the final value of
2147483647, that is, no further increment is possible.
The value of the setting
Counter load value is loaded into counter value
CNT_VAL
either when the
LOAD
input is set to "True" or when the
Load Counter is set to
"Load" in the LHMI. Until the
LOAD
input is "True", it prevents all further counting.
1MRS757644 H
Basic functions
620 series
Technical Manual
205
