Liquid Controls IT375 - Manual (Page 18)

Sponsler, Inc. Model IT375 Versions Pg. 18
6.2 DC POWER VERSION
The DC power version will operate from an external power source between 9-28VDC and draws no more than 4mA.
This enables the instrument to be powered from AC mains with DC adaptors and eliminates the need to run separate DC
voltages in the field.
The instrument uses lithium batteries for backup if the DC power is interrupted. However, alarms and/or pulse outputs
are disabled if the DC power is interrupted.
Open collector outputs are also provided for high and low flow rate alarms. If a pulse output is programmed, terminals
5(-) and 6(+) will act as a pulse out. The output can sink up to 200mA and can be used to control external relays, lights
or audible alarms. The outputs are internally protected against inductive voltage spikes caused by relay coils etc. Both
outputs are independent and optically isolated.
The alarm setpoints can be programmed. The low flow alarm will switch on whenever the flow rate drops below the
programmed low flow rate setpoint. Similarly, the high alarm switches on whenever the flow exceeds the high flow rate
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 liters, then programming 5 will output one pulse every 5 liters. If an unscaled pulse output is programmed, output
pulses will occur at the flowmeter input frequency.
Specification for Alarm Outputs
Maximum Current):
200mA. (sink)
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 CAL0 = 2 (unscaled pulse output).
If CAL0 = 1 (scaled pulse output) the duration of the pulse automatically adjusts to the
output frequency:
a. 1ms if output > 50Hz.
b. 10ms if output = 5...50Hz.
c. 100ms if output < 5Hz.
Power/4-20mA Loop
Low
Alarm
Opto-
Isolated
Outputs
High
Alarm
4 +
3 -
6 +
5 -
2 +
1 -
A
-
+
mA Meter
+ -
RL
For
Pulse
Low Alarm
<<
<<
<<
<<
High Alarm
9 - 28 VDC
4-20mA