Yokogawa 202 Field Mounting Rate Totalizer - Manual (Page 26)

Versions 22
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 adaptors and eliminates the need to run mains voltages in the
field.
The instrument uses lithium batteries for backup if the DC power is interrupted.
However, alarms and/or pulse outputs are not supported 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 6 and 5 will act as a pulse out. 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.
The switching points can be programmed during the setup mode and the low flow
alarm will switch on whenever the flow rate drops below the programmed flow
rate. 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. If an unscaled pulse output is programmed, output pulses
will follow input frequency from a flowmeter.