ElmoMC SimplIQ Digital Servo Drives-Bell Command Reference - Manual (Page 231)

Chapter 5: Limits, Protections,
Faults and Diagnosis
This chapter describes the limits and protections implemented by SimplIQ drives. Limits
are software restrictions that prevent SimplIQ drives from running into dangerous
situations. For example:
Limits set for the torque command prevent the motor or SimplIQ drive from burning.
Reaction to limit switches stops the motor before it accidentally hits something
out of its expected motion range.
Protections prevent the motor from starting, or shut down an active motor due to
abnormal situations. For example:
Bad or inconsistent setup data prevents the motor from starting.
An unexpectedly high motor current can endanger the
SimplIQ drive and the
motor. Such a high current is abnormal because the command to the current
(torque) amplifier is limited. If the current controller seems to be functioning
poorly, the drive is immediately shut down.
The drive is too hot.
When the drive shuts down due to a protection, the motor continues to run on its own
inertia unless brakes are used. In order to avoid spurious motor shutdowns, always:
Leave enough space between the limits and the protection. For example, HL[2] specifies
the over-speed limit. A protection is activated when VX > HL[2]. VH[2] specifies the
legal command to the speed controller. Speed commands over VH[2] are clipped to
VH[2]. The protection HL[2] must be greater than the limit VL[2]. Moreover, the
distance HL[2] -VH[2] must leave enough space for the expected speed overshoot.
When safety is a concern, always use brakes. SimplIQ drives can program one of
their digital outputs to activate a brake immediately upon motor shutdown.
If an exception stops the motor or prevents the motor from starting, the SimplIQ drive, in
most cases, can identify the cause of the event. If a real-time exception reaction is desired,
a #@AUTO_ER routine can be added to the user program
The following commands are used with limits and protections:
Command Description
BP[N] Brake parameters.
CD Dumps the process status of the SimplIQ drive and reports database
inconsistencies.
CL[N] Continuous current limit and “Motor not moving” protection.
EC Error code describing why previous command returned an error.
ER[N] Tracking error exception limits for speed and position.
HL[N] Protection high limits for position and speed feedback.
SimplIQ for Steppers Application Note Commutation and Pole Identification
MAN-STECR (Ver. 1.1)
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