SIEMENS
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Siemens IK PI · 2015
AS-Interface
Slaves
Modules with special functions
Counter modules
4
■
Overview
Counter module with spring-type terminals
The counter module is used to send hexadecimally coded count
values (LSB=D0, MSB=D3) to a higher-level controller. The
count value is increased by one for each valid count pulse at
terminal 8. Beginning at 0, the module counts up to 15 and then
begins again at 0. The controller adopts the current value and
determines the number of pulses between two host invocations
through subtraction from the previous value. The total number of
count pulses is determined by adding these differences.
For the values sent to be unambiguous, no more than 15 count
values are allowed between two host invocations or AS-Interface
master invocations at terminal 8. The maximum permissible
transmission frequency is calculated from these times:
f
TRmax
= 15 / T
max
T
max
: max. possible transmission time from the slave to the host
A further condition for the maximum frequency is the required
pulse shape. For the counter to accept a pulse as valid, a Low
must have been applied at the input for at least 300 μs and a
High for at least 1 ms.
This results in a maximum frequency of
f
Zmax
= 1 / 1.3 ms =
769 Hz independently of the control system (see figure below).
Maximum frequency for the counter module
If the time criterion stipulated in the figure is violated, the count
value is rejected.
The counter is active only for the reset parameter P2 (default).
The counter is deleted when P2 is set, and the incoming count
pulses are not registered until after P2 is reset again.
Note:
A customized function block is necessary or must be
programmed.
Counter module connection options
■
Selection and ordering data
U
IN1
≥ 1 ms
≥ 300
s
t
NSA0_00084
Terminal 9:
Sensor supply -
Terminal 8:
Counter input
Terminal 7:
Sensor supply +
Terminal 6:
Unused
Terminal 5:
Bus connection ASi -
Terminal 4:
Bus connection ASi +
+
-
IN1
ASi-
ASi+
ADDR
ASi
IN1
NSA0_00085
Version
Article No.
3RK1200-0CE03-0AA2
3RK1200-0CG03-0AA2
Counter modules
Width 22.5 mm
• With screw terminals
3RK1200-0CE03-0AA2
• With spring-type terminals
3RK1200-0CG03-0AA2
© Siemens AG 2014