©
2019 CDI Meters, Inc.
10.19
P
ULSE
O
UTPUT
The pulse output is open-collector,
that is, a transistor switch to the meter’s
negative supply. To use it, connect it to the input of the receiving device; also
connect that input through a 10K Ohm resistor to a suitable positive supply and
connect the negative supply of the receiving device to the negative supply of the
meter. If an isolated relay contact is required, install the CDI 5200-IPO isolated
pulse output and wire it to the receiving device.
S
ERIAL
C
OMMUNICATION
O
PTION
The RS-485 signal used with the Serial Communication option is wired to the
Serial Communication display board. The two threaded openings in the meter
enclosure permit the signal to be wired from meter to meter without external
splices. Please refer to the data sheet for the Serial Communication option.
Using the Outputs
The milliamp output is scaled so that four milliamps corresponds to zero flow and
20 milliamps corresponds to the range of the meter indicated on the data sheet.
The meter will display the milliamp full-scale value for a few seconds on startup.
It will also display it if the button on the main (lower) circuit board is pressed
twice.
The pulse output generates a square wave signal, sending one pulse for each
cubic foot of air that passes through the meter. The LED blinks with the pulse
output. At zero flow it may be on or off. The pulse output can be configured as a
threshold output, and the scaling of both the pulse output and the milliamp output
can be changed, using the optional configuration cable.
Using the Display
Pressing a button indicated by a circle on the front of the meter cycles the display
through four display options: rate, daily usage, cumulative usage and units of
measure, the last indicated by a digit: (0) for scfm, (1) for m
3
/min and (2) for
m
3
/hr. The cumulative values are indicated in thousands of cubic feet or cubic
meters. Holding the button pressed in either of the cumulative modes (daily
usage or cumulative usage) will reset that value to zero. The display normally
defaults to the rate display, but this can be changed, as can the units of measure
and the decimal point location in the cumulative modes. Please refer to
information on configuring the display.
Maintenance
If oil or dirt accumulates on the probes, the meter will read inaccurately. For this
reason, we recommend cleaning the probes from time to time. To clean the
probes, wipe them with a cloth dampened with alcohol or a similar degreaser. It
may be found that the system is clean enough that cleaning is not needed.
