EUCHNER CES-FD-AP-U-01-xxx (Unicode) - Manual (Page 6)

Operating Instructions Field Evaluation Unit CES-FD-AP-.-01-…
6
Function
Field evaluation units series CES-FD-AP make it possible to evaluate CES read
heads in the field. The safety outputs on the field evaluation units are connected
to the machine control.
The system meets the following safety requirements:
Ì Safety category 4, PLe according to EN ISO 13849-1
Ì Redundant design of the circuit in the unit with self-monitoring
Ì This means that the safety system still functions even if an internal component
fails
Ì The switch state of the semiconductor outputs is continuously monitored inter-
nally
Ì Short circuit detection at the safety outputs by pulsed signals
The following switch-on condition applies for the safety outputs FO1A and FO1B
(see also System state table and section Typical system times):
Ì Safety guard closed
The system consists of three components: coded actuator (transponder), field
evaluation unit and read head.
The read head is connected to the field evaluation unit and reads the actuator code.
Every EUCHNER actuator supplied has an electronic coding (unique coding) that is
read by the read head. Only if a correct coding is detected does the system accept
the actuator. The code in an actuator cannot be reprogrammed.
Unlike systems with unique code detection, on multicode systems a specific code
is not requested but instead it is only checked whether the actuator is of a type
that can be detected by the system (multicode detection). There is no exact com-
parison of the actuator code with the code defined in the safety switch (unique
code detection).
The read head is fastened to the fixed part of the safety guard.
The actuator attached to the movable part of the safety guard is moved towards the
read head by closing the door. The read head is connected to the field evaluation
unit. When the switch-on distance is reached, power is supplied to the actuator
by the read head by induction and data can be transferred.
If a permissible code is detected, the safety outputs are released.
Due to the combination of dynamic polling of the actuator and the redundant,
diverse design of the safety electronics with the two feedback safety outputs, the
safety switch will enter the safe state with every detectable fault.
When the safety guard is opened, the safety outputs switch off the safety circuit
and the monitoring output OD (optional) is switched off. The state of the safety
outputs is monitored internally by two microprocessors.
If faults are detected, the safety circuit is switched off and the DIA LED illuminates.
In case of devices with a monitoring output OI, the output is switched on.
The field evaluation unit has a redundant switching design with self-monitoring. This
means that the safety system is still effective even if a component fails.
The system is designed so that failures will not result in the loss of the safety func-
tion. The occurrence of failures is detected by cyclic self-monitoring at the latest
on the next demand to switch on the safety outputs (e.g. on starting).
If the safety door with the actuator should settle over time, the actuator can drift
out of the read head operating distance. The device recognizes this situation and
indicates that the actuator is in the limit range. This allows the safety door to be
readjusted in time.