Signet 9900 Operating Instructions Manual page 20

Relay Outputs
The 9900 open collector and relays are selectable and
confi gurable and can be used as switches that respond when
the process value moves above or below a user-defi ned
setpoint or it can be used to generate a pulse at a rate
proportional to the process value.
They can be used for Low Alarm, High Alarm or Proportional
Pulse triggering related to the process value. All relay
functions are set up in the RELAY menus.
Relay energized
Relay de-energized
Process
Hysteresis
Low Setpoint
Process
High Setpoint
Hysteresis
Process
High Setpoint
Hysteresis
Relay energized
Relay de-energized
If power is lost to the 9900 Transmitter during a
cycle, the Cycle Time will reset. If the condition
still exists after power is restored, the relay will be
energized for the complete Cycle Time.
20 9900 Transmitter
Time
Cycle Time
Time
CAUTION!
Open Collector Output
● Longer life than a mechanical relay
● No moving parts
● Faster ON/OFF switching capabilities than mechanical relays
● Can switch DC voltage only (< 30 VDC)
● Not recommended for use with inductive loads.
Low Setpoint:
Relay is on when the measured value is less than the setpoint.
High Setpoint:
Relay is on when the measured value is higher than the setpoint.
Time
Cycle High/Low:
The relay can stay energized for a set length of time after the
process value goes above (or below) the setpoint.
The relay will stay on for the CYCLE TIME and then turn off,
even if the process value is still above (or below) the setpoint.
The cycle will not repeat until the process value goes below
(or above) the setpoint minus the hysteresis after the relay
times out.
In FLOW, Cycle High activates the relay each time the volume
reaches the SET VOLUME setpoint (see page 28).
NOTE: To reset the timer (or volume in Flow): in the RELAY
menu, select TEST RELAY function. The timer will reset to 0
if the condition no longer exists when the TEST is performed.
The timer will restart if the condition still exists.