12.3 EDM1 (External Device Monitor)
12.3.1 EDM1 Output Signal Specifications
12-11
12
Safety Functions
12.3
EDM1 (External Device Monitor)
The EDM1 (External Device Monitor) signal is used to monitor failures in the HWBB. Connect
the monitor signal as a feedback signal, e.g., to the Safety Unit.
Note: To meet performance level e (PLe) in EN ISO 13849-1 and SIL3 in IEC 61508, the EDM1 signal must be mon-
itored by the host controller. If the EDM1 signal is not monitored by the host controller, the level will be safety
performance level c (Plc) and SIL1.
•
Failure Detection Signal for EDM1 Signal
The relationship between the EDM1, /HWBB1, and /HWBB2 signals is shown below.
Detection of failures in the EDM1 signal circuit can be achieved by using the four status of the
EDM1 signal in the following table. A failure can be detected by checking the failure status,
e.g., when the power supply is turned ON.
12.3.1
EDM1 Output Signal Specifications
If an HWBB is requested by turning OFF the two HWBB input signal channels (/HWBB1 and /HWBB2)
when the safety function is operating normally, the EDM1 output signal will be turned ON within 8 ms.
Signal
Logic
/HWBB1
ON
ON
OFF
OFF
/HWBB2
ON
OFF
ON
OFF
EDM1
OFF
OFF
OFF
ON
WARNING
The EDM1 signal is not a safety output. Use it only for monitoring for failures.
8 ms max.
/HWBB1
/HWBB2
/EDM1
OFF (motor current shut-OFF request)
ON
(normal operation)
OFF
ON
