Siemens SIMATIC S7-300 FM 350-1 Manual page 29

Input Filters for 24 V Encoder Signals
For the purpose of suppressing interference, you can parameterize input filters
(RC elements) with a uniform filter time for the 24 V inputs A*, B* and N*. The following two
input filters are available.
Table 3- 2
Characteristics
Typical input delay
Maximum frequency of count
Minimum pulse width of the count signals
Digital Inputs DI Start, DI Stop and DI Set
You can use digital inputs DI Start and DI Stop for the gate control of the counter. Gate
control can be both level-controlled and edge-controlled (refer to the chapter Operating
Modes, Parameters and Commands (Page 83)).
Digital input DI Set is used to set the counter to the load value.
The digital inputs are operated with a nominal voltage of 24 V.
The digital inputs are optically isolated from the bus of the S7-300 and the counter inputs.
Input Filters for Digital Inputs
For the purpose of suppressing interference, you can parameterize input filters DI-Start,
DI-Stop and DI-Set (RC elements) with a uniform filter time for digital inputs. The following
two input filters are available.
Table 3- 3
Characteristics
Typical input delay
Maximum frequency of the input signals
Minimum pulse width of the input signals
FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01
Input Filters for 24 V Encoder Signals
Input Filters for Digital Inputs
3.1 Pin assignments of the front connector
Input Filter 1
(default)
1 μs
200 kHz
2.5 μs
Input Filter 1
(default)
1 μs
200 kHz
2.5 μs
Wiring the FM 350-1
Input Filter 2
15 μs
20 kHz
25 μs
Input Filter 2
15 μs
20 kHz
25 μs
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