Configuring Sm 1226 F-Di 16 X 24 Vdc Di And Channel Parameters; Sm 1226 F-Di 16 X 24 Vdc Di Parameters - Siemens SIMATIC S7 Functional Safety Manual

5.3

Configuring SM 1226 F-DI 16 x 24 VDC DI and channel parameters

Table 5- 2

SM 1226 F-DI 16 x 24 VDC DI parameters

DI parameters
Short-circuit test
Interval for short-circuit
test (see T_int in figure
below)
Duration of short-circuit
test (see T_dur in figure
below)
Vsx Vs1 or Vs2 sensor supplies (VDC)
T_int Short-circuit test interval (time period) between the OFF pulses of the sensor supply
T_dur Short-circuit test OFF pulse time duration (msec)
S7-1200 Functional Safety Manual
Manual, 02/2015, A5E03470344-AA
5.3 Configuring SM 1226 F-DI 16 x 24 VDC DI and channel parameters
Description
This test creates short duration OFF pulses on
the sensor power supplies. Input circuits pow-
ered by Vs1 and Vs2 are expected to be OFF
during the sensor OFF time. Failure to detect
OFF when a sensor supply is OFF indicates a
short-circuit to a power source or another fault
that prevents the input from properly detecting
a "0". Input channels which fail this test are
passivated.
During the test, the reported process value will
not change, so the configured "Duration of
short-circuit test" increases the response time.
An actual process "0" occuring near the begin-
ning of a test will not be reported to the user
program until after the "Duration of short-circuit
test" time has elapsed.
The check box must be selected to activate the
short-circuit test.
This value is the time between the OFF pulses
of the sensor supply.
Refer to the figure below for further information.
Note: The interval must be a minimum of eight
times the duration.
This value is the time that the power supply
remains off during the test. The short-circuit
test OFF pulse must be long enough for the
external sensors and wiring to respond and
present a "0" to the inputs.
Refer to the figure below for further information.
Note: The interval must be a minimum of eight
times the duration.
Fail-Safe signal module (SM) I/O configuration
Default
Check box dese-
lected
25.6 ms
1.6 ms
Options
Check box:
Selected
•
Deselected
•
12.8 ms
•
25.6 ms
•
51.2 ms
•
102.4 ms
•
204.8 ms
•
409.6 ms
•
819.2 ms
•
1.6 ms
•
3.2 ms
•
6.4 ms
•
12.8 ms
•
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