Murphy Digital Loop Monitor MDM45 - Manual (Page 2)

Typical Wiring
1. Connect a ground wire to the NEG terminal of the MDM45 (Fig. 1).
2. Connect a wire from the NEG terminal to the TP1 negative (-) terminal.
3. Connect a wire from the TP1 negative (-) to the TP2 negative (-) terminal.
4. Connect DC power source positive (+) to the 12/24 positive (+) terminal.
5. Connect TP1 and TP2 positive terminals (+) to the annunciator, shutdown
device, or DC load such as a relay coil.
6. Using shielded cable, connect the 4-20 mA input signal negative terminal (-)
to the transmitter input positive terminal (+) of the MDM45. For separate
transmitter power source (Fig. 2), connect the 4-20 mA input signal nega-
tive (-) to the transmitter input negative terminal (-).
7. Connect the transmitter input negative terminal (-) to NEG terminal. For
separate transmitter power source, using shielded cable connect the trans-
mitter input negative terminal (-) to 4-20 mA input negative terminal (-).
8. Using shielded cable connect 4-20 mA input signal positive (+) to the 12/24
positive terminal (+). For a separate transmitter source, connect the 4-20
mA input signal positive (+) to the transmitter input positive terminal (+).
Calibration Procedures
1. Connect 10 VDC to 30 VDC power to power input terminal 10-30 Vdc
and negative as shown in wiring diagrams. (Observe polarity).
2. Remove the plugs from front panel for access to decimal point selector
switch, zero and span potentiometers (Items B, G and H, Figure 3).
3. Set decimal point by closing rocker switch that corresponds to the desired
decimal point position, (Item B, Figure 3).
Switch “1” on = Four (4) decimal digits (.0000 - 1.9999)
Switch “2” on = Three (3) decimal digits (0.000 - 19.999)
Switch “3” on = Two (2) decimal digits (00.00 - 199.99)
Switch “4” on = One (1) decimal digit (000.0 - 1999.9)
Switch “5” on = No decimal digit (0000 - 19999)
4. Connect the 4–20 mA source to the transmitter input terminal as shown in
Figure 2 below, left.
5. Set current source to 20 mA and rotate coarse span potentiometer R9
(Item H, Figure 3) clockwise until display indicates approximately the
maximum range.
6. Fine tune the setting with R44 fine span potentiometer (clockwise to increase ).
7. Set current source to 4 mA and rotate coarse zero potentiometer R24
(Item G, Figure 3) clockwise until display reads near zero.
8. Fine tune the setting with R45 fine zero potentiometer (clockwise to increase).
9. Switch current source back to 20 mA. Observe display and adjust coarse
span or fine span potentiometer until display indicates the desired value.
10. Set current source to 4 mA observe display and adjust coarse zero or fine zero
potentiometer until zero is displayed. Repeat steps 5 thru 10 if necessary.
NOTE: Transmitter may not be perfectly calibrated to provide 4 mA at zero
input or 20 mA at maximum input. If this is the case it may be desirable to
adjust the monitor to match the transmitter or recalibrate transmitter.
Trip Point
Adjustments
1. Start engine or power up the monitor.
2. Set trip point display toggle switch to “Low Trip PT” potentiometer.
3. Press “Push To Read” trip point button to read the low trip point.
4. While depressing the “Push To Read” button, rotate the “Low Trip PT”
potentiometer until the LCD display indicates the desired low trip point
(rotate clockwise to increase value).
5. Set trip point display toggle switch to “High Trip PT” potentiometer.
6. Press “Push To Read” trip point button to read the high trip point.
7. While depressing the “Push To Read” button, rotate the “High Trip PT”
potentiometer until the LCD display indicates the desired high trip point
(rotate clockwise to increase value).
INSTALLATION
12/24
NEG
TP1
L
L
MDM45
Back view
=LOAD L
TP2
4-20 mA
Signal
NC
12/24
NEG
TP1
L
L
MDM45
Back view
12/24 VDC
=LOAD L
TP2
4-20 mA
Signal
Transmitter Input
Terminal Block
12/24 VDC
NC
Transmitter Input
Terminal Block
NOTE: Loads must not exceed
0.5 A @ 250 VDC.
All grounds (-) must be common.
NOTE: Loads must not exceed
0.5 A @ 250 VDC.
All grounds (-) must be common.
A. Trip point display toggle switch.
B. Decimal point adjustments.
C. Trip point potentiometers.
D. LED trip point indication lights.
E. Readout digital display.
F. Push to read trip point button.
G. Low limit range coarse and
fine zero adjustments.
H. High limit range coarse and
fine span adjustment.
WARNING: Perform this operation with the power source OFF.
Figure 2: Separate Transmitter Power Source
Figure 1: Common Transmitter Power Source
A
C
D
E
F
R45
Side
View
ON
1 2 3 4
Front View
G
R24
H
R9
R44
C
D
B
5
Figure 3: Faceplate Diagram
Printed in U.S.A. 0791157
®
FRANK W.
MFR.
■ Frank W. Murphy Manufacturer
P.O. Box 470248; Tulsa, Oklahoma 74147; USA
tel. (918) 627-3550 fax (918) 664-6146
e-mail [email protected]
■ Frank W. Murphy Southern Division
P.O. Box 1819; Rosenberg, Texas 77471; USA
tel. (281) 342-0297 fax (281) 341-6006
e-mail [email protected]
Since 1939
■ Frank W. Murphy, Ltd.
Church Rd.; Laverstock, Salisbury SP1 1QZ; U.K.
tel. +44 1722 410055 fax +44 1722 410088 tlx 477088
e-mail [email protected]
■ Frank W. Murphy Pte., Ltd.
26 Siglap Drive; Republic of Singapore 456153
tel. +65 241-3166 fax +65 241-8382
e-mail [email protected]
■ Murphek Pty., Ltd.
1620 Hume Highway; Campbellfield, Vic 3061; Australia
tel. +61 3 9358-5555 fax +61 3 9358-5558
In order to consistently bring you the highest quality, full featured products, we reserve the right to change our specifications and designs at any time.
■ Murphy de México, S.A. de C.V.
Blvd. Antonio Rocha Cordero 300, Fracción del Aguaje
San Luis Potosí, S.L.P.; México 78384
tel. +52-48-206264 fax +52-48-206336
e-mail [email protected]
■ Murphy Switch of California
P.O. Box 900788; Palmdale, California 93590; USA
tel. (805) 272-4700 fax (805) 947-7570
e-mail [email protected]
■ Frank W. Murphy France
tel. +33 1 30 762626 fax +33 1 30 763989