Functions; Count - Siemens Simatic series Manual

2.2

Functions

2.2.1

Count

Introduction
As of firmware version V2.1.0 of the module you have the option of using channels 0 and 1
in the "Count" mode. The other channels can be used as standard inputs (DI mode).
If do not use channels 0 and 1 in the "Count" mode, these channels can also be used as
digital inputs. The two channels 0 and 1 can only be used as counter inputs together.
When counting, the edges of the digital input are acquired and evaluated accordingly e.g.:
● For counting single items up to a maximum limit
● For applications with repeating counting procedures
Reference
You will find the basics and additional information on the counting function in the function
manual Counting, measuring and position detection
(http://support.automation.siemens.com/WW/view/en/59709820).
Counting with channel 0 and channel 1
You control the counting function via the IO addresses of the module. These IO addresses
are also known as the control interface (output addresses) and feedback interface (input
addresses), see section AUTOHOTSPOT.
If you set the parameters of channels 0 and 1 for counting, you then have the following
options:
● You influence the behavior if one of the counting limits is exceeded using
– Stop counting.
– Continue counting.
● The bit STS_DQ (bit in the feedback interface) signals that the counted value is in one of
the following ranges depending on the parameter assignment:
– Between a comparison value and the high counting limit.
– Between a comparison value and the low counting limit.
● You can set a parameter for a hardware interrupt if a comparison event occurs for DQ.
● You can define counting limits and comparison values for counting from 0 ... 4294967295
(2
● You can set start values or have the user program set load values for counting.
The count direction is only up.
Reference
You will find examples of counting with channels 0 and 1 in the section Examples of counting
(Page 30)
DI 16x24VDC HF Digital Input Module (6ES7521-1BH00-0AB0)
Manual, 08/2018, A5E03485952-AG
-1).
32
Product overview
2.2 Functions
13