3.2 Inputs and Output
3.2.1 Permitted Sensor Types on Digital
Inputs
The following list describes how digital inputs are activated
depending on sensor types:
•
NCNC: A digital input is active when there is 0 V
at both channels of the input.
•
Antivalent: A digital input is active only when
there is 0 V at channel A and 24 V at channel B.
•
NC: The functionality is similar to NCNC.
Sensors with 2 NO contacts are not applicable.
The safe digital inputs are configured for both directly
connected safety sensors, e.g. emergency stop control
devices or light curtains, as well as for pre-processing
safety relays, for example safe controls. See examples of
connecting the safe digital input, in accordance with EN
ISO 13849-1 and EN IEC 62061 in
.
3.2.2 Inputs
The dual channel digital inputs are used to activate the
safety functions.
1 or both digital inputs can be disabled.
DI 1 can have 1 of the following functions:
•
STO: Safe Torque Off.
•
SO Mon: Safe option monitoring through the safe
fieldbus.
DI 2 can have 1 of the following functions:
•
STO: Safe Torque Off.
•
SO Mon: Safe option monitoring.
•
Reset: Additional safe input to reset the safety
option after an error, or after deactivating a
safety function on input DI1.
3.2.3 Safe Option Monitoring (SO Mon)
The PLC can use the digital inputs of the safety option as
safe inputs. If a digital input is set to
Safe Option
Monitoring
(SO Mon), the safety option maintains all signal
checks (discrepancy, etc.) on the digital inputs, but the
safety option does not activate safety functions in case of
a signal change. All safety logic is carried out by the PLC.
3.2.4 Output
S37 is the safe, single-channel output that goes to the STO
input of the frequency converter. For information about
the events that trigger STO, see
3.2.5 Signal Filtering
If a sensor with NC-NC or antivalent is selected, the safety
option checks the signals of the safe digital input for
consistency. If NC-NC is selected, consistent signals at both
inputs always assume the same signal state (high or low).
If antivalent is selected, it checks the correct state of each
input.
With electromechanical sensors (for example emergency
stop buttons or door switches), the 2 sensor contacts are
never activated at the same time due to discrepancy. A
long-term discrepancy leads to a fault in the wiring of a
safe input, for example, a wire break. An adjustable filter in
the safety option prevents errors caused by temporary or
short-term discrepancy. Within the filter tolerance time
42-22 Discrepancy Time
, the safety option suppresses the
discrepancy when monitoring the safe inputs.
If the signals have different levels after the discrepancy
time expires, the option responds with an external error.
NOTICE
The discrepancy time does not extend the safety option
response time. The safety option activates its safety
function as soon as there is a signal transition on one of
the 2 channels of a digital input.
Functions
Operating Instructions
MG37F102
Danfoss A/S © 10/2014 All rights reserved.
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