Intended Use Of The Sto Function; Safety Characteristics; Foreseeable Misuse Of The Sto Function; Diagnostic Coverage (Dc) Of The Motor Controller - Festo CMMO-ST-C5-1-DIOP Manual

Safety and requirements for product use
2.1.2

Intended use of the STO function

The motor controller supports the "safe torque off" safety function (STO, Safe Torque Off ) in accord-
ance with EN 61800-5-2. The STO function is intended to disconnect the torque from a motor that is
connected to the CMMO-ST, thereby preventing an unexpected restart of the motor. The STO function
should only be used for applications for which the stated safety characteristics are sufficient.
2.1.3

Safety characteristics

The STO function of the CMMO-ST satisfies the requirements for the following safety characteristics:
– PL e/Cat. 3 in accordance with EN ISO 13849-1
– SIL 3 in accordance with EN 61800-5-2
– SIL CL 3 in accordance with EN 62061
The achievable safety level depends on the other components that are used to implement the safety
function. To protect against unintended start-up, the motor controller must be activated via the
connection [X3] with the category required for the application according to EN ISO 13849-1, e.g. via an
external safety relay unit.
2.1.4

Foreseeable misuse of the STO function

The following incorrect applications are classified as non-intended use:
– bypassing the safety function
– use in applications where switching off can result in hazardous movements or conditions.
The STO function does not provide protection against electric shock, only against dangerous move-
ments!
2.1.5

Diagnostic coverage (DC) of the motor controller

Diagnostic coverage (è 5 Technical data) is influenced by the interconnection of the motor controller
in the control chain as well as the measures implemented for diagnostic purposes. In order to achieve
the diagnostic coverage, the status of the acknowledgment contact must be evaluated by the control
system with each request of the STO function. If the signal does not correspond to the expected
value, a potentially dangerous malfunction may be pending, e.g. cable break. In this case, appropriate
measures must be implemented to maintain the safety level.
NOTICE
The motor controller cannot detect a cross circuit in the input circuit by itself.
• Find out if detection of shorts across contacts is required for the input circuit and wiring in your
application.
• If required, use a safety relay unit with detection of shorts across contacts.
2.2

Requirements for product use

For correct and safe use of the product in a machine or system:
– Provide the complete product documentation to the following specialists
– the design engineer and installer of the machine or system
– the personnel responsible for commissioning
– Keep the documentation available throughout the entire product lifecycle.
– Ensure compliance with all of the specifications in the documentation for the motor controller è 1.1
Applicable documents
– Also take into consideration the documentation for the other components (e.g. motor, cables etc.)
Festo — CMMO-ST-C5-1-DIOP/DION — 2022-05e 7