Hardwired Safe Torque-Off; Description Of Operation - Rockwell Automation MagneMotion QuickStick HT User Manual

Hardwired Safe Torque-off

This section introduces the QuickStick HT 5700 inverter hardwired safe torque-off (STO) fea-
ture that meets the requirements of Performance Level e (PL e) per ISO 13849-1 and SIL CL
3 per IEC 61508, IEC 61800-5-2, and IEC 62061.
The MMI-HT-C2198-D032 inverter uses the STO connector for wiring external safety
devices and cascading hardwired safety connections from inverter-to-inverter.

Description of Operation

The safe torque-off feature provides a method, with sufficiently low probability of failure, to
force the power-transistor control signals to a disabled state. When disabled, or any time
power is removed from the STO inputs, all of the QSHT 5700 inverter output-power transis-
tors are released from the ON-state. This results in a condition where the inverter performs a
Category 0 Stop (see
For hardwired control of the safe torque-off (STO) function the appropriate wiring must be
connected to the Safety (STO) connector plug. See
Specifications on page 279
Falling of suspended or inclined loads, or a stopped position where one end of the vehicle
magnet array is engaged by the coils in a stator but the other end is not creates potential
energy that could result in unintended motion. In these cases, the force from gravity acting on
the load, or the asymmetric force from magnetic attraction between the magnet array and the
stators, can cause motion. Note that these scenarios are in effect without cause from any sort
of system failure.
Under normal operation, shown in
inputs are energized. If either of the STO inputs are de-energized, then all of the output power
transistors turn off and both axes will fault with the same error. The safe torque-off response
time is less than 12 ms.
QuickStick HT User Manual
Stop Category Definition on page
ATTENTION: Disabling the power transistor output does
not provide physical isolation of the electrical output that is
required for some applications.
for more information on the safety inputs.
ATTENTION: In circumstances where external influences
(for example, falling of suspended or inclined loads, or a
stopped position where one end of the mover magnet array is
engaged by a stator but the other end is not) are present, addi-
tional measures (for example, mechanical brakes) are neces-
sary to prevent any hazard.
Figure 7-1
Rockwell Automation Publication MMI-UM007F-EN-P - September 2020
QSHT 5700 Inverter Safe Torque-off Function
Hardwired Safe Torque-off
264).
Hardwired Safe Torque-off Electrical
and described in Table 7-3, the safe torque-off
269