Endress+Hauser Proline Promag 300 - Page 15

Proline Promag 300 HART Design
Endress+Hauser 15
The device additionally communicates for information only via HART and contains all HART
features with additional device information. HART communication is not part of the safety
function.
The safety-related output signal is fed to a downstream logic unit, e.g. a programmable logic
controller or a limit signal transmitter, where it is monitored for the following:
• Overshooting and/or undershooting of a specified limit value
• The occurrence of a fault: e.g. failure current (≤ 3.6 mA, ≥ 21 mA, signal cable open circuit
or short-circuit)
In the event of a fault, it must be ensured that the equipment under control achieves or
maintains a safe state.
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 Item no →  1
Impact on measuring
uncertainty
Implication for safety-related
output signal
No device error Safe:
No error
1
Within specification
None
λ
SD
Safe detected:
Safe, detectable failure present
3
No implications
Causes a failure current at the
output signal
λ
SU
Safe undetected:
Safe, undetectable failure
present
2
May be outside specifications
Is within the defined error range
λ
DD
Dangerous detected:
Dangerous but detectable failure
present (diagnosis in device)
3
No implications
Causes a failure current at the
output signal