Standstill Monitoring (Sos, Ss2) - Mitsubishi Electric MELSEC Q Series Programming Manual

1 OVERVIEW

1.4.5 Standstill monitoring (SOS, SS2)

1.4.6 Safe brake control (SBC)
(1) The position dependent safety observation function (SOS) is based on two
independent safety-related sensors. One of them is part of the motor, which has a
built-in encoder (for functional motion control); the other must be provided by the
customer's application (e.g. an external sensor, PLG).
For standstill monitoring when using a safety encoder, an external auxiliary pulse
signal is not necessary.
(2) During Safe Operating Stop, make sure that monitoring status is enabled by small
oscillation before a certain period of time (about one hour) elapses in the stop
status. However, an error cannot be detected in the check interval. (The derivation
of failure until next check cannot be detected.) If stop time becomes long, use
Safe Brake Control (SBC) as mechanical lock or perform Safe Torque Off (STO).
(3) Avoid the continuous use of Safe Operating Stop (SOS) for eight hours or more to
prevent the accumulation of failure. If stop time becomes long, use Safe Brake
Control (SBC) as mechanical lock or perform Safe Torque Off (STO).
(4) Encoder position feedback data does not guarantee the range out of the small
oscillation. Therefore, make sure that motor encoder feedback position can
operate normally in the machine mobile region. At least, the performance check of
motor mobile region is required.
(5) The position assurance of the motor with SOS is 1.75 pulses, and 1 pulse with
safety encoder with the external auxiliary input pulse conversion.
(1) This function guarantees only that power to mechanic brake is properly supplied.
Abrasion of the brake cannot be detected. Make sure regularly that the mechanic
brake operates.
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