10. Safety system
MiR250 User Guide (en) 11/2020 - v.1.3 ©Copyright 2020: Mobile Industrial Robots A/S. 88
Safety-related electrical interfaces
The following interfaces are parts of the Auxiliary emergency stop and Auxiliary safety
function interfaces that can be used to connect the safety PLCto a top module—see Internal
parts on page21.Each electrical interface is redundant, meaning they use two identical
circuits. If one of the circuits fail, the robot enters Protective stop until both circuits are
working correctly again and the robot is restarted, ensuring safe communication between
the top module and robot—see Interface specifications on page199.
The following list introduces the main safety-related electrical interfaces between MiR250
and its top module:
• Emergency stop circuit
The Emergency stop circuit goes through the Auxiliary emergency stop interface and
connects to the top module. It is intended that any number of Emergency stop buttons can
be connected to the circuit. When the circuit is broken, the robot goes into Emergency
stop.
• Safeguarded stop
This function consists of a circuit that goes through the Auxiliary safety function interface
that connects to the top module. This circuit can be used to bring the robot into Protective
stop until otherwise signaled.
• Locomotion
The locomotion function signals when the robot is driving. A top module can be connected
to this interface if the top module should operate differently when the robot is driving,
such as activating brakes or disconnecting the power to actuators.
• Shared emergency stop
This function consists of a shared circuit between the robot and top module, enabling
them to trigger each other into an Emergency stop.
• Reduced speed
The reduced speed function can be connected to a top module, enabling it to make the
robot reduce its speed to 0.3 m/s. This is for example used by MiR lifts to ensure that the
robot does not drive fast when the lift is raised.
These functions are described in further detail in the following sections.
The diagram in Figure 10.3 shows the inputs to these functions and interfaces and how they
are all connected and monitored by the safety PLC. The safety PLCis able to switch the
safety contactors to cut off power to the robot motors and the top module whenever a
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