Safety engineering
Device modules
Safe speed measurement and position detection
1
42
EDS94AYAE EN 6.0
1.2.7 Safe speed measurement and position detection
For a safe speed and position detection, you must connect a safety−approved sin/cos
encoder to terminal X8 (Sub−D).
Alternatively, you can connect a 2−encoder system, consisting of motor encoder and
position encoder from SM301 V1.3. When selecting a 2−encoder system, you can also
select a resolver as motor encoder.
From SM301 V1.4, the resolver can be selected as the motor encoder without needing an
additional position encoder. The response time of the encoder monitoring must be set to
50 ms or 100 ms.
Safe speed measurement
Motor encoder
system
Max. speed Synchronism Response time of
encoder monitoring
Error response
[rpm] [%] [ms]
Encoder
±16000
1
12
Error stop STO
From SM301 V1.2:
12/50/100can be
parameterised
( 1.8.4)
Resolver ±10000 / no. of
resolver pole pairs
1
From SM301 V1.3:
12/50/100can be
parameterised
( 1.8.4)
Tab. 1−3 Detailed features
Explanations on the data:
ƒ Synchronism
Fluctuation of the detected speed at constant input signal.
ƒ Response time of encoder monitoring
Time required to detect faults due to continuous signal errors at the encoder interface.
ƒ Tolerance of speed monitoring
Time required to detect ... faults.
Note!
If speed monitoring is active and the standard device detects the inverter error
characteristic (C00002=71) or determines the motor parameters (C00002=72),
the error message "Safe speed invalid" is displayed. Both functions cannot be
completed since the SM301 activates STO. These two states generally occur
only once during commissioning.
Therefore, these functions should be carried out before the speed monitoring
is activated in the SM301.
A plausibility check regarding the speed detected from the standard device and the safety
module takes place. The maximum deviation allowed (after a filter time of approx. 2
seconds) is set to a limited value of 20 rpm up to SM301 V1.2. The filter time of approx. 2 s
belongs to the diagnosis function and is independent of the response time. From
SM301 V1.3, this tolerance limit can be parameterised (C15411).
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