DATEL, Inc., Mansfield, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
E-mail: sales@datel.com
Internet: www.datel.com
Features
DMS-20PC Series, 3 Digit, LED Display, Digital Panel Voltmeters combine a
precision A/D converter; a factory-trimmed, highly stable, voltage reference; and a
large (0.37"/9.4mm), easy-to-read LED display in a single package that is only
slightly larger than the display itself. Displays are offered in either red, orange,
amber, yellow, green or blue colors. High-intensity and low-power (35mW total) red
LED's are also optional.
These low-cost meters are fully self-contained and fully functional. Their
subminiature (1.38" x 0.88" x 0.48"), epoxy-encapsulated cases incorporate built-in
color filters and bezels; are moisture and vibration proof; and function well in the
harshest environments. Their 12-pin, dual-in-line configuration offers component-like,
plug-in convenience and maximum versatility. Operating temperature range is 0 to
+60C.
The meters come with one of four, differential, input voltage ranges: 200mV, 2V
20V or 200V. Input impedance is a minimum 800k
. CMRR is typically 86dB (dc
to 60Hz), and CMV is 2V. Input overvoltage protection (on the non-inverting input)
is 250V. Devices are fully calibrated at the factory to an accuracy of 1 count
(0.05% of full scale range) and never require calibration or adjustment.
A DISPLAY ENABLE function permits the display to be disabled for "power-
down" operation. All models have a DISPLAY TEST function. Standard red LED
models offer an optional DISPLAY HOLD function.
Small size, low cost and adjustment-free reliability make the DMS-20PC Series
the best choice for all your 3 digit, LED, DPM applications.
Figure 1. DMS-20PC Series Simplified Schematic
Lowest-cost LED meters
Subminiature size:
1.38" x 0.88" x 0.48"
35mm x 22mm x 12mm
Large (0.37"/9.4mm) LED display
Choice of 6 LED colors
High-intensity or low-power (7mA) red
LED's optional
Epoxy-encapsulated, 12-pin DIP package
with built-in color filter and bezel
4 differential input voltage ranges
Factory calibrated, 1 count accuracy
Single +5V power supply
User-selectable decimal point placement
DISPLAY ENABLE function for
"power-down" mode
DISPLAY TEST and HOLD (optional)
functions
0 to +60C temperature range
3 Digit, LED Display
Low-Cost, Subminiature
Digital Panel Voltmeters
DMS-20PC Series
Actual Size
(+) INPUT HI
() INPUT LO
ANALOG
COMMON
REFERENCE OUT
REFERENCE IN
+5V SUPPLY
R1
DP 1
DP 2
DP 3
6
5
4
11
12
10
8
7
1
3
DC/DC
CONVERTER
2
5V RETURN
+5V
5V
R2
+2.0V
DATA
909k
V+
V
A/D
CONVERTER
0 Vdc
0.01
F
9
DISPLAY
ENABLE
+5V
R2 is not used on 200mV (-0) models or 2V (-1) models.
R2 = 100k on 20V (-2) models and 9.1k on 200V (-3) models.
Only used on 200mV (-0) and 2V (-1) models.
DISPLAY
TEST/HOLD
11
Pin 9 is DISPLAY TEST on all but eight models. On those models
(-H option), it is DISPLAY HOLD.
1
2
3
2
1
3
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Super-Bright Blue
LED Models
NEW!
2
DMS-20PC
3 D I G I T , L E D D I S P L A Y D I G I T A L P A N E L V O L T M E T E R S
Performance/Functional Specifications
Typical at T
A
= +25C and supply voltage = +5V using the single-ended input circuit,
unless otherwise noted.
Applies for transient or continuous overvoltages applied to (+) INPUT HI (pin 11)
with () INPUT LO (pin 12) properly connected. Pin 12 is not overvoltage protected
(see Figure 1). Voltages applied to pin 12 should not exceed the supply voltage.
See Technical Notes.
The DISPLAY HOLD function is optional on standard red and green LED models only.
See Ordering Information.
Leave blank for standard
models.
Add
-H
for DISPLAY
HOLD option (available on
standard red and green
LED models only).
DMS-20PC - 1 - RS
LED Color:
AS
= Standard Amber
BS
= Standard Blue
GS
= Standard Green
OS
= Standard Orange
RS
= Standard Red
YS
= Standard Yellow
RH
= High-Intensity Red
RL
= Low-Power Red
Accessories:
DMS-PS1-CM
+5V/1.0A AC/DC power supply module
DMS-20-CP
Panel cutout punch
DMS-BZL3
DMS-20 bezel assembly
DMS-BZL4
DMS-20 bezel assembly with sealing gasket
DMS-EB2
Application/evaluation board with standard
MOLEX connector, decimal point solder pads
and attenuation resistor pads.
Technical Notes
1. REFERENCE OUTPUT (Pin 8) and INPUT (Pin 7):
Pin 8 is a
precision reference actively trimmed at the factory. In normal
operation, pin 8 must be tied to pin 7 to achieve all listed accuracy
and drift specifications.
2. ANALOG COMMON (Pin 10):
This pin is connected to an internal,
low-noise, "relative" ground. It is used in certain differential and
"floating" measurements as described in the Applications section
of this data sheet and Ap Note 3 of the DATEL Panel Meter Catalog.
Pin 10 should not be connected to pin 3 (5V RETURN) or to
your system's analog ground.
3. Decimal Point Placement:
The location of the decimal point is
user-selectable, and the decimal point control pins (DP1-DP3) are
active low functions. Select the appropriate decimal point by tying
the appropriate pin (pin 4, 5 or 6) to pin 3 (5V RETURN). Unused
decimal point location pins should be left open.
Hard wiring is preferable, however, you can use logic gates to
exercise dynamic control over the location of the decimal point if the
following drive conditions are met:
Model
Applied "0" Voltage
Load Current*
DMS-20PC-X-RL
+0.05V max.
0.7mA max.
All Others
+0.4V max.
6mA max.
* The driving gates must be able to sink this much current
(I
OL
) with a logic "0" output.
Ordering Information
Input Range:
0
= 200mV
1
= 2V
2
= 20V
3
= 200V
A panel-mount retaining clip is supplied with each model.
Analog Inputs
Min.
Typ.
Max.
Units
Full Scale Input Range:
DMS-20PC-0
--
200
--
mV
DMS-20PC-1
--
2
--
Volts
DMS-20PC-2
--
20
--
Volts
DMS-20PC-3
--
200
--
Volts
Input Impedance:
DMS-20PC-0, -1
100
1000
--
M
DMS-20PC-2, -3
0.8
1
--
M
Overvoltage Protection
--
--
250
Volts
Common Mode Voltage Range
--
--
2
Volts
CMRR
(dc to 60Hz)
--
86
--
dB
Control Inputs
Decimal Point Placement
(Pins 4-6)
Tie to pin 3 to activate
Display Test (Pin 9)
Tie to pin 1 to activate all segments
Display Hold (Pin 9)
Tie to pin 1 to hold last reading
Performance
Sampling Rate
2.5 samples per second
Accuracy
(3 minute warm-up):
DMS-20PC-0 (V
IN
= +0.19V)
--
1
3
Counts
DMS-20PC-1 (V
IN
= +1.9V)
--
1
3
Counts
DMS-20PC-2 (V
IN
= +19V)
--
2
3
Counts
DMS-20PC-3 (V
IN
= +190V)
--
2
3
Counts
Zero Reading
(V
IN
= 0 Volts)
" 001"
"000"
"001"
Temperature Drift
(0 to +60C)
--
0.2
0.4
Cnts/C
Power Supply Requirements
Supply Voltage
+4.75
+5.00
+5.25
Volts
Supply Current:
DMS-20PC-X-RL
--
+7
+12
mA
DMS-20PC-X-RS, -RH
--
+60
+90
mA
DMS-20PC-X-RS-H
--
+60
+90
mA
DMS-20PC-X-BS
--
+75
+100
mA
DMS-20PC-X-GS-H
--
+90
+120
mA
DMS-20PC-X-AS, -GS, -OS, -YS
--
+90
+120
mA
Display
Display Type and Size
3 Digit LED, 0.37"/9.4mm high
Polarity Indication
Autopolarity ("" for negative V
IN
)
Overrange Indication
"1_ _ _ " for negative V
IN
"1_ _ _ " for positive V
IN
Physical/Environmental
Operating Temperature
0
--
+60
C
Storage Temperature
40
--
+75
C
Humidity
(Non-condensing)
0
--
95
%
Case Material
Polycarbonate
Weight
0.4 ounces (11 grams)
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3
3 D I G I T , L E D D I S P L A Y D I G I T A L P A N E L V O L T M E T E R S
DMS-20PC
Applications
Figure 2. Single-Ended Input Configuration
8. Suggested Mating Connectors:
Panel mounted:
Connector housing
DATEL P/N 39-2079400
Terminal type
DATEL P/N 39-2099090
Crimping tool
DATEL P/N 39-2099000
Wire size
22 to 26 AWG
Insulation diameter
0.062" (1.57mm) maximum
Stripping length
0.100 to 0.125" (2.54 to 3.17mm)
Board mounted:
Socket
DATEL P/N 39-2359625
DMS-20PC meters are highly versatile devices that can be used in
hundreds of applications. The application circuits chosen for this
section are ones that have historically received many inquiries.
The schematic in Figure 1 shows that the meter's high-impedance
input consists of an op amp powered from a 5Vdc power supply
(the 5V is internally generated). One can easily see why input
signals applied to () INPUT LO and (+) INPUT HI have to be kept
within the power supply rails of 5V. Also note that only pin 11 has a
current-limiting 909k
series resistor. High input voltages that have
a common ground with pin 3 (5V RETURN) should only be applied
to pin 11 ((+) INPUT HI) and never to pin 12. In these high-voltage
cases,
pin 12 should always be tied to pin 3 (5V RETURN).
The schematic also shows that pin 3 is the meter's zero-volt
reference point -- regardless of the type of power or signal source
used. This is an important point to keep in mind when a digital or
analog multimeter is used to make system measurements. The
multimeter's negative lead (usually the black one) must be
connected to pin 3 (5V RETURN).
1. Single-Ended Input Configurations:
True single-ended
measurements can be made with any DMS-20PC meter. The
circuit of Figure 2 avoids problems normally associated with
ground-loop currents. Separate ground runs should be used
for 5V RETURN (pin 3) and () INPUT LO (pin 12).
4. DISPLAY TEST/HOLD (Pin 9) Function:
Pin 9 is a dual-function
pin. On all standard models (without "-H" suffix), tying pin 9 to pin
1 (+5V SUPPLY) activates the meter's DISPLAY TEST feature.
All display segments, except the decimal points, will be
illuminated. The display will show "1888" ("1888" if a negative
input signal is present).
Do not leave the meter in the test
mode for more than 10 seconds as this will cause the
meter's operating temperature to rise and possibly affect its
performance.
Pin 9 must be left open when the test function is
not being used.
On models with the "-H" suffix (DMS-20PC-1-RS-H for example),
pin 9 serves as a DISPLAY HOLD control pin. Tying pin 9 to +5V
SUPPLY (pin 1) on these models will hold or "freeze" the current
display reading indefinitely. Pin 9 must also be left open when the
hold function is not being used. After disabling DISPLAY HOLD,
allow the meter a full 10 seconds to resume normal calibrated
operation before holding a new reading.
The DISPLAY TEST or DISPLAY HOLD pin should normally be
connected, via a selector switch, to pin 1 (+5V SUPPLY). If
automatic, logic-controlled operation is desired, only PNP or
MOSFET transistors should be used. The base or gate of these
transistors should be driven sufficiently hard to bring pin 9 within
0.05V of +5V SUPPLY.
5. DISPLAY ENABLE (Pin 2) Function:
On all models, tying pin 2
to pin 1 (+5V SUPPLY) applies full power to the LED display. This
is the normal mode of operating the meter. Leaving DISPLAY
ENABLE open (no connection), only turns off the LED display.
The meter's analog-to-digital converter continues to sample the
input signal. Total current consumption with the display off is
approximately 400A (0.4mA). This is a very useful feature if the
meter is used in battery-powered equipment.
With the exception of the low-power red LED models (DMS-
20PC-X-RL), a regulated voltage lower than +5V SUPPLY can be
used to dim the display intensity. Display intensity control is best
performed with the high brightness, red LED, DMS-20PC-X-RH
model. All low-power red LED models must have DISPLAY
ENABLE tied directly to pin 1 (+5V SUPPLY). Voltages applied to
DISPLAY ENABLE must never be greater than +5V SUPPLY.
6. Gain Adjust:
There is a gain-adjust potentiometer on the back
of each meter. It has approximately 50 counts (2.5%) range of
adjustment. Since these devices essentially have no zero/offset
errors, a gain adjustment is effectively an overall accuracy
adjustment. Though they may be performed at any point (except
zero), accuracy adjustments are most effective when performed
with higher level input signals. The circuit shown in Figure 10
provides 10% range of adjustment.
7. Soldering Methods:
All models in the DMS-20PC Series easily
withstand most common wave soldering operations. We
recommend, however, that you evaluate the effects your
particular soldering techniques may have on the meter's plastic
case and high-precision electrical performance. We recommend
the use of water-soluble solders and thorough cleaning
procedures.
1
1 2
3
+ 5 V S U P
( ) I N L O
5 V R E T
D A T E L
D M S - P S 1 - C M
8 5 - 2 6 4 V a c
1 1
( + ) I N H I
6
D P 1
+
A C t o D C C o n v e r t e r
V
I N
D M S - 2 0 P C - 1
7
R E F O U T
R E F I N
8
2
D I S P L A Y
E N A B L E
4
DMS-20PC
3 D I G I T , L E D D I S P L A Y D I G I T A L P A N E L V O L T M E T E R S
Figure 3. Differential Input Configuration
Figure 6. Floating Input Measurements
(Alternate Configuration)
R
Shunt
= R1 = V
Fsr
/ I
Fsr
Where:
V
Fsr
= Full scale reading (in Volts)
I
Fsr
= Relative full scale current (in Amps)
R2
R1 + R2
x V
IN
= Reading
50k
< R1 + R2 < 10M
Figure 4. Input Attenuation Circuit
Figure 5. Floating Input Measurements
Applications
to () INPUT LO (pin 12) provides the reference point for the
meter's input.
A "floating" input is a signal that has no galvanic connection
to the meter's power supply. In the figures below, the 1.5V
battery illustrates a true floating input.
5. Process Control (4-to-20mA) Measurements:
In many
common process-control applications, a 4-to-20mA current loop is
used to transmit information. Because DMS-20PC meters have
such high input impedance, a simple shunt resistor across the
meter's input can be used to convert the loop current to a voltage.
See Figure 7. The value of the shunt resistor is a function of the
scaling requirements of the particular application and can be
calculated using the following equation:
4. Floating Signal Source Measurements:
Floating signals can
be measured using the circuits shown in Figures 5 and 6.
Connecting pin 10 (ANALOG COMMON) or pin 3 (5V RETURN)
3. Engineering Scaling:
For measuring voltages greater than the
full scale input range of a given meter, the input signal must be
attenuated. A simple voltage divider (similar to that shown in
Figure 4) will scale the input to within the range of the selected
meter. R1 and R2 should be precision, 1%, metal-film resistors
with absolute TCR's less than 50ppm/C. See Ap Note 4 for more
information on engineering scaling.
2. Differential Input Configurations:
Differential measurements
can be made with all DMS-20PC meters. Figure 3, though not a
practical real-world application, uses a voltage divider to
demonstrate the concept of a differential input signal. Be careful
not to exceed the 2V common mode voltage limitation for 5V-
powered meters.
1
1 2
3
+ 5 V S U P
( ) I N L O
5 V R E T
1 1
( + ) I N H I
6
A C t o D C C o n v e r t e r
D M S - 2 0 P C - 1
R 2
R 1
R 3
1 k
1 k
1 k
8
7
R E F I N
D P 1
R E F O U T
2
D I S P L A Y
E N A B L E
D A T E L
D M S - P S 1 - C M
8 5 - 2 6 4 V a c
D M S - 2 0 P C - 1
R 2
1 1
1 2
( + ) I N H I
( ) I N L O
V
I N
R 1
+
1
3
+ 5 V S U P
5 V R E T
A C t o D C C o n v e r t e r
8
7
R E F O U T
R E F I N
2
D I S P L A Y
E N A B L E
D A T E L
D M S - P S 1 - C M
8 5 - 2 6 4 V a c
1
3
+ 5 V S U P
6
D P 1
A C t o D C C o n v e r t e r
D M S - 2 0 P C - 1
1 2
( ) I N L O
1 1
( + ) I N H I
1 . 5 V
C E L L
+
8
7
R E F O U T
R E F I N
2
D I S P L A Y
E N A B L E
5 V
R E T
D A T E L
D M S - P S 1 - C M
8 5 - 2 6 4 V a c
D M S - 2 0 P C - 1
1 2
( ) I N L O
1 0
A N A C O M M
1 1
( + ) I N H I
1 . 5 V
C E L L
+
8
7
R E F O U T
R E F I N
1
3
+ 5 V S U P
6
D P 1
A C t o D C C o n v e r t e r
2
D I S P L A Y
E N A B L E
5 V
R E T
D A T E L
D M S - P S 1 - C M
8 5 - 2 6 4 V a c
5
Applications
3 D I G I T , L E D D I S P L A Y D I G I T A L P A N E L V O L T M E T E R S
DMS-20PC
Figure 8. 4.5V -18V Power Supply Monitor
Figure 10. External Gain Adjustment
Figure 7. 4-to-20mA Current Loop Operation
To calibrate the circuit of Figure 7, perform the following:
1. With 4mA applied, adjust the 50k
potentiometer (R2) to
display a reading of "000" (assuming that is the desired
reading).
2. With 20mA applied, adjust the gain-adjust potentiometer on
the back of the meter to display a reading of "1000". For different
full scale readings, alter the value of R
Shunt
accordingly.
Figure 9. DC Ammeter Circuit
The LM-2931 was chosen because it has the following on-chip
protection features: reverse polarity, short circuit and thermal
runaway. When using other, higher-power, DMS-20PC models
with three-terminal regulators, be sure to consult the regulator
manufacturer's data sheet to ensure the regulator is being
utilized safely and correctly.
7. Digital Ammeter:
Digital ammeters are finding ever-increasing
usage because analog-style ammeters (moving-vane types) now
cost roughly the same as their digital counterparts. Additionally,
analog ammeters are not nearly as rugged as modern digital
panel voltmeters. Figure 9 illustrates a typical ammeter
application. The circuit uses a 200mV input meter -- the
preferred range for most ammeters -- to measure the voltage
developed across a 0.1
current shunt. The circuit shown
represents a basic ammeter connection diagram. A detailed
application note describing digital dc ammeters is included in
DATEL's new Digital Panel Meter Databook.
8. External Gain Adjustment:
Connect REFERENCE OUT
(pin 8) to REFERENCE IN (pin 7) for normal, factory calibrated,
operation. Use the circuit shown in Figure 10 for applications
needing external gain adjustment. Calibration is performed with
a precise, near-full-scale, input voltage.
6
.
Power Supply Monitoring:
One of the most common digital
panel meter applications involves monitoring the output voltage
of the system power supply -- often this supply also powers the
meter itself. The low-power, red LED DMS-20PC-2-RL can be
configured to allow power supply monitoring over the range of
4.5-18Vdc. The circuit in Figure 8 uses a low-drop-out, three-
terminal regulator (LM-2931Z-5, available from National
Semiconductor) to provide regulated 5V-power to the meter.
Example: For a meter with a 2V full scale input (1.999 full scale
reading) and a desired display reading of "1000" (with an input
of 20mA), V
Fsr
= 1.000 Volts
R
Shunt
= 1.000V/(0.020 0.004)A
R
Shunt
= 1.000V/0.016A = 62.5 Ohms
1
3
+ 5 V S U P
5 V R E T
A C t o D C C o n v e r t e r
D M S - 2 0 P C - 1
1 2
( ) I N L O
1 0
A N A C O M M
1 1
( + ) I N H I
R 1
+
4 - 2 0 m A
5 0 k
R 2
8
7
R E F O U T
R E F I N
2
D I S P L A Y
E N A B L E
D A T E L
D M S - P S 1 - C M
8 5 - 2 6 4 V a c
5
7
8
+
DMS-20PC-2-RL
12
11
1
4.5 - 18Vdc
LM2931Z-5
GND
IN
OUT
+5V SUP
3
DP2
REF
IN
REF
OUT
() IN LO
5V RET
2
DISP EN
(+) IN HI
22F
10V
+
6
3
+
DMS-20PC-0
11
0.150V
1
1.5 Amp (Load Current)
5Vdc
7
8
+5V SUP
5V RET
DP1
(+) IN HI
REF OUT
REF IN
2
DISP EN
0.1
W
R
Shunt
Load
(3.3 )
12
() IN LO
W
12
VOLTAGE
CALIBRATOR
OUT
10
(+) IN HI
() IN LO
ANA
COMM
= 10 to 20 Turns
7
REF
IN
11
732, 1%
8.06k, 1%
5V RET
Connections
for 2V, 20V
and 200V models
Connections
for 200mV
models
COM
17.4k, 1%
2k
24.3k, 1%
3
12
DMS-20PC-1
8
NC
200
+5V IN
1
1
1
1
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151
Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356
Internet: www.datel.com Email: sales@datel.com
DATEL (UK) LTD. Tadley, England Tel: (01256)-880444
DATEL S.A.R.L. Montigny Le Bretonneux, France Tel: 01-34-60-01-01
DATEL GmbH Mnchen, Germany Tel: 89-544334-0
DATEL KK Tokyo, Japan Tel: 3-3779-1031, Osaka Tel: 6-6354-2025
DATEL makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein
do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without notice. The DATEL logo is a registered DATEL, Inc. trademark.
ISO 9001
ISO 9001
R
E
G
I
S
T
E
R
E
D
DS-0271C 2/02
DMS-20PC
3 D I G I T , L E D D I S P L A Y D I G I T A L P A N E L V O L T M E T E R S
MAD
E IN
US
A
DMS-20PC-X-XX
FRONT VIEW
DP1
DP2
DP3
PIN #1
IDENTIFIER
+5V SUPPLY
DISPLAY ENABLE
5V RETURN
DP3
DP2
DP1
1
2
3
4
5
6
() INPUT LO
(+) INPUT HI
ANALOG COMMON
DISPLAY TEST/HOLD
REFERENCE OUT
REFERENCE IN
12
11
10
9
8
7
0.80
(20.3)
0.15
(3.8)
TYP.
0.50
(12.7)
0.10
(2.5)
TYP.
0.040
(1.02)
0.040
(1.02)
1.10
(27.9)
0.10
(2.5)
TYP.
0.25 (6.4) TYP.
0.475 (12.07)
0.040
(1.02)
1.30
(33.0)
1.38
(35.1)
0.88
(22.4)
0.170
(4.32)
0.150
(3.81)
PIN 1
0.125 (3.175) DIAMETER
(USE ONLY WHEN
PC BOARD MOUNTING)
CALIBRATION POTENTIOMETER HOLE LOCATION
Mechanical Specifications
MECHANICAL DIMENSIONS: Inches (mm)
TOLERANCES: 2 PL DEC 0.02 (0.51)
3 PL DEC 0.010 (0.254)
LEAD DIMENSIONS: 0.025 (0.635) x 0.025 (0.635) NOMINAL
RECOMMENDED PC BOARD FINISHED HOLE DIAMETER:
0.042 0.003 (1.067 0.076)
#2-56 INSERT
0.156 (3.96) DEEP
FRONT VIEW
1.280
(32.51)
0.187
(4.75)
OPTIONAL BEZEL (DMS-BZL3 and DMS-BZL4)
RECOMMENDED DRILL AND PANEL CUTOUT DIMENSIONS
1.826 (46.38)
0.838
(21.29)
1.336 (33.93)
1.626 (41.30)
1.07
(27.18)
INTERNAL CORNER RADII:
0.032 (0.81) MAX.
0.145
(3.68)
0.093 (2.362) DIAMETER (4 REQUIRED)
ONLY WHEN USING OPTIONAL BEZEL ASSEMBLY
0.116
(2.95)
BEZEL INSTALLATION
BEZEL
PANEL
RETAINING CLIP INSTALLATION
PANEL
PDF 
ZIP