User's Guide _______________________________________________________________________
114 ______________________________________________________________________________
Mode 4 is usually used if an alarm needs to be triggered when the
measured value exceeds a safe range. The relay is active when
measurement is in range, and is released if the value goes out of range
or the measurement fails.
NOTE
If the measurement of the selected quantity fails or the transmitter
loses its power, the relay is released.
Hysteresis
Hysteresis function is to prevent the relay switching back and forth
when the measured value is near to the setpoint values.
Relay is activated when the measured value passes the exact value of
the setpoint. When returning and passing the setpoint again relay is
not released before the value reaches the setpoint increased/decreased
by the hysteresis value.
Hysteresis should be smaller than difference of the setpoints.
Example:
When the 'active above' value is 60 %RH and the hysteresis
value is 5 %RH, relay activates when the relative humidity reaches 60
%RH. As the humidity decreases, relay releases at 55 %RH.
NOTE
If both setpoints are specified and "above" setpoint is lower than
"below" setpoint, the hysteresis works in the opposite direction, that
is, relay is
released
when the measured value passes the exact value
of the setpoint.
Relay Indicating Transmitter Error
Status
You can set a relay to follow the operation status of the device. By
selecting FAULT/ONLINE STATUS for output quantity a relay
changes state on the basis of the operation status as follows:
FAULT STATUS
Normal operation: relay active (C and NO outputs are closed)
Not measuring state (error state or power off): relay released (C and
NC outputs are closed)
