Vaisala PTU300 - Manual (Page 137)

Chapter 4 _________________________________________________________________ Operation
VAISALA _______________________________________________________________________ 135
1102-040
Figure 61 FAULT/ONLINE STATUS Relay Output Modes
FAULT/ONLINE STATUS relays are usually used in conjunction with
an analog output to obtain validity information for the output value.
NOTE If transmitter loses its power, all status-based relays are released
similarly to the case of an instrument failure.