Speed Monitoring Function (Sls); System Configuration Of Speed Monitoring Function - Mitsubishi Electric MELSEC Q Series Programming Manual

2 SAFETY OBSERVATION FUNCTION

2.4 Speed Monitoring Function (SLS)

2.4.1 System configuration of speed monitoring function

(1) Functions
Motion CPU and PLC CPU execute the following monitoring function.
• Command speed monitoring
: Command speed does not exceed the safety speed.
• Feedback speed monitoring
: Motor speed does not exceed the safety motor speed.
• Position deviation monitoring
: Difference between command position and feedback position does not
exceed the allowance value.
• Speed deviation monitoring
: Difference between command speed and feedback speed does not
exceed the allowance value
• External auxiliary pulse input monitoring
: Difference between accumulation of external auxiliary pulse input and
feedback position does not exceed the allowance value
If the above speed and difference exceed the allowance value, the Safety
observation error occurs and the shut-off signal is turned OFF. The response
time (response time for input/output signal is excluded) of speed monitoring
function is within 50 [ms].
The external auxiliary pulses are used as safety signals to confirm the validation
of motor encoder. The external auxiliary pulse signal is input via safety signal
module, and diagnosed by the safety signal comparison function. The validation
of pulse signal is guaranteed by this diagnosis, so the special devices are not
required.
When performing speed monitoring function with a safety encoder compatible
servo amplifier and a safety encoder, external auxiliary pulse is not necessary.
The safety response time of a system that uses a safety communication
compatible servo amplifier is up to 250ms. The response time includes the
maximum response time of the controlling section (PLC CPU and Motion CPU),
communication delay, communication timeout, and the maximum time to start the
STO of the servo amplifier. Take the above response time into account when
shutting off power supply by the STO function in safety communication.
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