Functional Description - Festo EMCA-EC-67 Serie Traducción Del Manual Original

EMCA-EC-67-...
2.2

Functional description

The STO function is requested over 2 channels via switch S1, whereby the control voltage (+24 V DC,
logic è Fig. 2) is switched off at both control ports STO 1 and STO 2.
The control ports should be switched simultaneously. The discrepancy time between the two inputs is
monitored (max. 50 ms). If the permissible discrepancy time is exceeded, a diagnostic message is gen­
erated. Monitoring of the discrepancy time is only informative. Monitoring of the discrepancy time is not
a part of the safety function.
The EMCA monitors the status of the control ports. The control ports are of equal value. As soon as
logic 0 (0 V) is present at one of the control ports, the EMCA reacts as follows:
– Channel 1 (STO 1): As long as logic 0 is present at the STO 1 input, the output stage drivers are not
supplied with voltage. The motor will not generate a torque.
– Channel 2 (STO 2): As long as logic 0 is present at the STO 2 input, no pulse-width modulation sig­
nals will be forwarded to the driver component. The motor will not generate a torque.
Behaviour of the drive when the STO function is requested
– Behaviour of the drive with a running motor: The movement of the drive is not decelerated via a
braking ramp. The drive continues to move uncontrolled through inertia or external forces until it
comes to a standstill by itself.
– Behaviour of the drive with a stopped motor: The drive is uncontrolled and can move through external
forces.
The 2-channel shut-down of the motor is indicated by the acknowledgment contact NC1/NC2 (semicon­
ductor relay) (è Tab. 8). The status of the STO function can be reported to an external safety switching
device for diagnostics, for example, via the acknowledgment contact. The acknowledgment contact is
not evaluated for safety purposes.
+24 V DC
1
STO 1
STO 2
1
Input circuit (e.g. safety switching device)
2
Bus transmitter supply voltage for
the pulse-width modulation signals
Fig. 3 "Safely switched off torque" (Safe torque off/STO) – functional principle
30
2 3
6 6
3
4
+24 V DC load voltage
3
6
Driver supply
MOSFET output stage
Festo – EMCA-EC-67-... – 1603 English
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