Cameron NUFLO MC-III, User Manual

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21
MC-III™ Panel Mount Flow Analyzer Section 2
Output Wiring
The MC-III Panel Mount supports four outputs: pulse output, 4 to 20 mA output, flow meter frequency (amp
& square) output, and RS-485 output. Wiring diagrams for each feature are provided below.
Pulse Output
The pulse output is a solid-state relay. Each pulse represents a user-defined volume. Because the circuit is
isolated, it can be used in conjunction with any other feature on the MC-III Panel Mount. A two-conductor
cable from the MC-III Panel Mount to the remote location is required. The maximum current rating of the
pulse output circuit is 60 mA at 30 VDC.
For information on configuring the pulse output with the keypad, see
34 . For information on configuring
the pulse output with the interface software, see
67
.
TB1
PU
LS
E
IN
PU
T
RE
SE
T
IN
PU
T
TF
M
A&S
GND
TB
3
EXT POWER
TB2
RS
48
5
SL
AV
E
4-2
0
OU
T
PU
LS
E
OU
T
6-3
0 V
DC
J1
J2
RESET
SWITCH
BA
TT
ER
Y
Leave this
end of shield
disconnected.
POWER SUPPLY
5 to 30 VDC
*
Resistor may be included in pulse readout
device. Size the resistor to limit the current
to 60 mA.
*
PULSE READOUT
DEVICE
Figure 2.7—Pulse output wiring
Analog (4-20 mA) Rate Output
The 4-20 mA rate output provides a linear current output that represents flow rate. This output requires a two-
conductor cable connected to an 8 to 30 VDC power supply (voltage required is dependent on loop resistance)
and a current readout device located in the remote location. The 4-20 mA rate output current loop also
powers the MC-III Panel Mount. The internal lithium battery provides a power supply backup to maintain
timekeeping accuracy and to continue accumulating volume in the event that the 4-20 mA current loop fails.
Figure 2.8, page 22, shows the minimum required voltage to power the instrument for a given loop
resistance. In addition, the mathematical relationship between loop voltage and load resistance is given. For
example, if a power supply voltage of 24 volts is available to power the current loop, the maximum load
resistance would be 800 ohms.
Caution: The 4-20 mA rate output and the flow meter frequency output circuits are not isolated
from each other and cannot be used simultaneously. When the 4-20 mA output option is
used, do not connect external power to TB3.
For information on configuring the 4-20 mA rate output with the keypad, see
33
. For information on
configuring the 4-20 mA rate output with the interface software, see 63 .