Proline Prosonic Flow P 500 HART Safety function
Endress+Hauser 11
In devices with several outputs, only current output 1 (terminals 26 and 27) is suitable for
safety functions. The other outputs can, if necessary, be connected for non-safety-oriented
purposes.
The safety-related output signal is fed to a downstream automation system where it is
monitored for the following:
• Overshooting and/or undershooting of a specified limit value for the volume flow
• The occurrence of a fault: e.g. failure current (≤ 3.6 mA, ≥ 21 mA), interruption or short-
circuit of the signal line
The safety-related errors are broken down in accordance with IEC/EN 61508 into different
categories and implications for the safety-related output signal.
Safety related
error
Explanation Position→ 12 Implication for safety-related output
signal
No device error Safe:
No error
1 Within specification
λ
SD
Safe detected:
Safe, detectable failure present
3 Device assumes a signal on alarm
λ
SU
Safe undetected:
Safe, undetectable failure present
2 Is within the specified tolerance range
λ
DD
Dangerous detected:
Dangerous but detectable failure
present (diagnosis in device)
3 Device assumes a signal on alarm
λ
DU
Dangerous undetected:
Dangerous, undetectable failure
present
4 May be outside the specified tolerance
range
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