6
Basic specifications
Device diagnostics and behavior of the module in the event of an error
Actuator
Single-channel
Achievable
SIL/SIL CL/Cat./PL
SIL 2/SIL CL 2/Cat. 2/PL c
External errors that can be
detected
If alarm inputs IN1 or IN2 are used:
1.
An external load does not pick up
2.
An external load does not drop out
Errors that cannot be
detected
If no alarm inputs are used, no errors can be detected in the external load or in the wiring.
External wiring
requirements
The user is responsible for error analysis for the connected loads and for the external
wiring.
WARNING: Loss of electrical and functional safety
–
To achieve the specified safety integrity level, please refer to Section "Measures
required to achieve a specific safety integrity level" on page 6-3.
–
Please note that in order to achieve the specified PL, the actuator must have a
medium level of diagnostic coverage (90% to 99%) and medium MTTF
d
.
–
Use actuators that can achieve the required safety integrity level.
–
Evaluate the readback contacts to achieve the corresponding safety integrity level.
–
Please note that when switching mains voltages, safe isolation to the PELV areas is
required.
Table 6-3
Single-channel: Alarm input assigned
Error type
Detection Diagnostics Loss of
SF
Remark
Error in the actuator
Despite being disabled, the
actuator does not switch to the safe
state (e.g., a contact will not open)
Yes
Yes
Yes
Please take into consideration all the possible errors for the
actuator used.
Test the shutdown capability of the actuator at regular
intervals.
Actuator cannot be enabled (e.g.,
interrupt at coil)
Yes
Yes
No
Please take into consideration all the possible errors for the
actuator used.
Interrupt on the N/C contact
Yes
Yes
No
The error is detected in the OFF state of the output.
Short circuit on the N/C contact
Yes
Yes
No
The error is detected in the ON state of the output. The output is
switched off.
Other errors
(depending on the actuator)
Please take into consideration all possible errors that can
occur in the actuator.
Error in the wiring
Interrupt
Cable interrupt between output and
actuator or between actuator and
ground
Yes
Yes
No
The error is detected in the ON state of the output. The output is
switched off.
Cable interrupt between clock
output/alarm input and actuator
Yes
Yes
No
The error is detected in the OFF state of the output.
Cross circuit
Output to output
No
None
Yes
Prevent this error.
Clock output/alarm input to
external signal
Yes
Yes
No
The error is detected by clocking or by the plausibility check.
6-6
User manual IC220SDL840 -
May 2018
GFK-2734