ABB TTF350 Operating Instructions Manual page 46

Field mounted temperature transmitters

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2-sensor input functionality / Dual sensor mode

Fig. 28: Alarm pulse signaling in redundancy mode for failure of the temperature characteristic for sensor 2

1 Temperature characteristic

for sensor 1 ------

2 Temperature characteristic

for sensor 2

3 4 ... 20 mA output signal

Example:

If a pulse rate of 10 seconds is set, the normal temperature signal of 4 ... 20 mA is found at the

output due to the pulse width refresh rate of 60 seconds after a 10-second pulse diagnostic

alarm signal, e.g., of 22 mA for 50 seconds.

The next cycle begins with a 10-second diagnostic alarm signal and subsequently again after 50

seconds with the normal 4 ... 20 mA temperature signal

4 Alarm pulse:

•

5 Wire break temperature characteristic 2

TTF350

Off

On -> Configurable pulse width

Continuous pulse

OI/TTF350-EN

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