Elgo LIMAX44 RED, Operating Manual

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Disturbances
12.2.3 Error Register
Each of the two sensor channels contains an error register that simplifies the error search. The content of the
error register is transmitted outside via the interface (

9.5.4 Protocol Descriptions).
Table 9: Content Error Register
Bit Problem
Error requires safe
state
0 Overvoltage or undervoltage in general Yes
1 … 6 Error in voltage monitoring Yes
7 Error position interpolation Yes
8 … 12 Internal communication error Yes
13 … 14 Synchronisation error Yes
15 EEPROM error No
1
16 Not used -
17 Comparing of position between the two channels failed Yes
18 Communication test failed Yes
19 Extrapolation not allowed anymore. Too many position jumps occurred Yes
20 Timeout in the non-safety-relevant processing No
21 Overvoltage 24V Yes
22 Undervoltage 24V Yes 2
23 … 31 Not used -
12.3 Severe Errors
If one channel detects a severe fault in the processor system (memory error, CPU-error, no communication with
the other channel), its firmware goes into a separate emergency loop and the processors are therefore purpose-
fully blocked. The external interface is not served anymore in this case. This mode is never reset if a voltage is
applied, no matter if normal or battery supply.
There is one exception for channel A to the reaction described above: when there is no communication with the
other channel and the normal supply voltage has a strong undervoltage and therefore channel A is in single-
channel operation. This means that channel B is deliberately switched off (

9.2.2 Single-Channel Operation).
Under this condition, channel A continues to send its positions and sets the relevant status bit (section Status Bits
in the chapter of the relevant interface

9.5.4). When the voltage returns and all error detection measures
operate in their entirety in both channels, LIMAX44 RED returns to normal operation (

9.2.1).
12.4 Informative Errors (not Safety-Relevant)
The two chapters 12.2 and 12.3 mainly treated errors in the safety-relevant processing which require the transi-
tion into safe state; either explicitly by sending the request for transition into safe state or implicitly due to missing
messages which cause a timeout in the evaluation unit.
In order to avoid non-safety-relevant operational elements influencing this behaviour, some information of a
purely informative character are exempted from the request for transition into safe state. Those errors can only
be identified over the error register (

12.2.3. Informative errors are also signalled via the error LED. Namely
these are errors in the EEPROM and timeout in the non-safety-relevant processing.
1
The EEPROM only contains the non-safety-relevant floor table for the indication of the door zones.
2 An undervoltage of the 24 V implicitly requests a transition into the safe state because in this case the second channel is
switched off in order to save energy and only a non-safe position is transmitted.