R.T.A. s.r.l. – XPETME05 – 11/20
28/29
12.10-
EDM (ERROR DETECTION MONITOR)
Error Detection Monitor output is a signal to monitor problems in safe-torque-off circuit or between
SAFETY UNIT and STO1 and STO2 inputs. The following Table 10 shows correspondences
between STO1 and STO2 inputs and Monitor Output states.
STO1
STO2
MONITOR OUT
ON
ON
OFF
ON
OFF
OFF
OFF
ON
OFF
OFF
OFF
ON
Table 10
12.11-
EDM – CONNECTION EXAMPLE
In Figure 17 is described a connection example that allows to enable Safe Torque Off function by
means of emergency stop button through SAFETY UNIT (Figure 17).
Under normal conditions, pressing emergency stop button, STO1 and STO2 become OFF and EDM
becomes ON (with maximum delay of 10 ms). When emergency stop button is released, if feedback
circuit of SAFETY UNIT is reset and two safety inputs are set ON, EDM becomes OFF. This allows
to restart the machine working.
12.12-
ERROR DETECTION METHOD
Errors between input logic states and monitor output must be detected by means of SAFETY UNIT.
For correct connections, please refer to the SAFETY UNIT manual.
EDM (Error Detection Monitor) is not a safety output. Do not use EDM for any purpose other than
failure monitoring.
12.13-
WARNING!
VERIFICATION TEST
Please verify that SAFE TORQUE OFF function properly works at every first machine start-up and at
every drive replacement.
Before check the correct working of SAFE TORQUE OFF function, please verify that every drive
connections properly operate.
Verification Test needs the following procedures:
1. Switch on the drive power supply.
2. Set ON both STO1 and STO2 inputs.
3. Verify that motor is in CURRENT ON state.
4. Verify corresponding EDM output state.
5. Set OFF both STO1 and STO2 inputs.
6. Verify that motor runs without holding torque and it is in CURRENT OFF state.
7. Verify corresponding EDM output state.
8. Repeat the points from 5 to 7 setting OFF STO1 and STO2 inputs separately.
12.14-
WARNING!
SAFETY CAUTIONS
Please thoroughly observe the following safety cautions to use safe-torque-off function.
Not correct use of safe-torque-off function can result to personal injury or death.
1. Safety system with safe-torque-off function must be designed by person with expertise of related
safety standards and through understanding the descriptions specified in this manual.
2. The security system development that involves the use of STO function must be the result of an
appropriate risk assessment.
3. When safe-torque-off function is active during the motor run, current motor is turned to zero and
the motor continues to run due to inertia. Please design safety system so that no risks occur until
the system stopped.
4. When the motor is used in vertical axes, the motor can rotate due to gravity. Please provide
external device (i.e. brake) to stop the motor within requested range.
