Yokogawa 202 Field Mounting Rate Totalizer - Manual (Page 23)

5. ALARM & PULSE
OUTPUTS
Open collector outputs are provided for high and low flowrate alarms. The
output can sink up to 200mA and can be used to power external relays, lights or
audible alarms. The outputs are internally protected against voltage spikes
caused by relays and coils.
Both outputs are separately isolated via opto isolators.
As an alternative to a high flowrate alarm, the output on terminals 7 and 8 can be
programmed to output a scaled pulse output.
The switching points can be programmed during the setup mode and the low
flow alarm will switch on whenever the flowrate drops below the programmed
flowrate. Similarly, the high alarm switches on whenever the flow exceeds the
high setpoint.
If a Scaled Pulse Output is programmed, a pulse will be output every preset value
of the total. For example, if the total is in litres, then programming 5 will output
one pulse every 5 litres. The duration of pulses is adjusted automatically to the
output frequency.
Specification for Alarm Outputs
Maximum Current (sink): 200mA.
Maximum Voltage: 30VDC.
Saturation Voltage: 0.8VDC across Outputs when in the "on"
state.
Isolation: Both outputs are separately isolated.
Pulse Frequency: 500Hz maximum.
Pulse Duration: 1ms if output frequency > 50Hz.
10ms if output frequency = 5 ... 50Hz.
100ms if output frequency < 5Hz.
Alarm & Pulse Outputs 21