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PHOENIX CONTACT 109241_en_03
5.2 Speed control
5.2.1 General information on the “Error Out” parameter
Figure 5-52 Example of an “OVER-SPEED” function block with activated “ERROR” out-
put
NOTE: Loss of functional safety
– An external error or an external malfunction of the encoder/proximity switch does not
necessarily lead to an unsafe state.
– The module detects and manages errors or malfunctions in the encoder/proximity
switch or the cabling and then signals them to each function block via the error output
(“E
RROR”). In order to do this, the “Enable Error Out” parameter must be selected in
the “Property” window of the speed function block.
– To maintain the safety function, the error output bit must be used in the safety
program created by the user in order to cause the possible deactivation of the
outputs when the axis is in operation (depending on the safety level). If there
are no external errors present on the encoder/proximity switch, the “E
RROR”
bit equals “0” (zero).
– If one of the following errors is present, the “E
RROR” bit equals “1” (one):
– No encoder/proximity switch connected
– Plausibility error between encoder and proximity switch
– Interruption of one or more signals from the encoder or proximity switch
– Encoder supply absent (only applies to TTL encoders with external supply)
– Plausibility violation between the encoder signals of a single phase
– Rectifying one of the above errors can result in unintentional machine startup. De-
pending on the risk assessment, prevent autostart by using a suitable reset block to
reset the safety function.
– An automatic restart can occur after initiating the safe state (e.g., after over-speed,
zero-speed, etc.). Depending on the risk assessment, prevent autostart by using a
suitable reset block to reset the safety function.
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