Martel 303 User manual

T2
HOLD
TYPE J
TYPE K
T1 T2
T1 T2
T1
2498F328 F
200
328
C
F
760
1400
C
F
200 C1370 C
CF
REL
303
TYPE K J THERMOMETER
MARTEL ELECTRONICS

C O N T E N T S
TITLE PAGE
I. Introduction ....................................................1
II. Specifications ................................................1
III. Symbol Definition and Button Location.3
IV. Operating Instructions ................................5
4.1 Power-Up......................................................5
4.2 Connecting the Thermocouples....................5
4.3 Selecting the Temperature Scale................. 5
4.4 Selecting the Thermocouple Type ................5
4.5 Data-Hold Operation.....................................5
4.6 T1, T2, T1-T2 Display Control ......................5
4.7 Relative Operation for Main Display .............6
4.8 MAX/MIN/AVG Operation for Main Display ....6
4.9 Auto Power Off .............................................7
4.10 Low Battery Condition ................................7
4.11 Digital Output ..............................................7

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I. Introduction:
This instrument is a digital thermometer for use with
any K-type and J-type thermocouple as temperature
sensor.
Temperature indication follows National Bureau of
Standards and IEC584 temperature/voltage table for
K-type and J-type thermocouples.
II. Specifications:
Numerical Display:
4 digital liquid crystal display
Measurement Range:
K-Type -200℃~ 1370℃
-328℉~ 2498℉
J-Type -200℃~ 760℃
-328℉~ 1400℉
Resolution:
K-Type:
-200°C~ 800°C, 0.1°C; 800°C ~1370°C, 1°C
-328°F~ 1000°F, 0.1°F; else 1°F
J-Type:
-200°C~ 600°C, 0.1°C; 600°C ~760°C, 1°C
-328°F~ 1000°F, 0.1°F; else 1°F
Maximum Voltage at Thermocouple Input:
60V DC, or 24Vrms AC
Environmental:
ROperating Temperature and Humidity:
0°C ~50°C (32°F ~ 122°F); 0~80% RH
RStorage Temperature and Humidity:
-10°C to 60°C (14°F ~ 140°F); 0~80% RH
RAltitude up to 2000 meters.

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Accuracy: at ( 23 ± 5°C )
Range Accuracy
K-Type -200°C ~ 1370°C ±(0.1% reading + 0.7°C)
J-Type -200°C ~ 760°C ±(0.1% reading + 0.7°C)
K-Type -328°F ~ 2498°F ±(0.1% reading + 1.4°F)
J-Type -328°F ~ 1400°F ±(0.1% reading + 1.4°F)
For T1-T2 Measurement, the accuracy is
±( 0.2% T1-T2 reading + 1.7°C) or
±( 0.2% T1-T2 reading + 3.4°F)
Temperature Coefficient:
For ambient temperatures from 0°C ~ 18°C and
28°C ~ 50°C, for each °C ambient below 18°C or
above 28°C add the following tolerance into the
accuracy spec.
0.01% of reading + 0.03°C ( 0.01% of reading + 0.06°F )
Note:
The basic accuracy Specification does not include
the error of the probe. Please refer to the probe
accuracy specification for additional details.
Sample Rate: 2.5 times per second
Dimension: 7.36”x2.56”x1.2” (184x64x30 mm)
Weight: 7.4oz. Approx. (210g)
Accessories:
K-Type Bead Probe, Battery, Carrying Case,
Instruction Manual
Options:
Software Package (Program, RS232 Connection
Cable), AC Adapter.
Power requirement:
9 Volt Battery, NEDA 1604 or JIS 006P or IEC6F22

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Battery Life:
Approx. 100hrs with alkaline battery
AC Adapter:
9VDC ±15% 100mA
III. Symbol Definition and Button
Location:
Main Display Second Display
-:This indicates that the minus temperature is
sensed.
°C °F :Centigrade and Fahrenheit indication.
K J :Thermocouple Type Indication
HOLD :This indicates that the display data is being held.
MAX :The Maximum value is now being displayed
MIN :The Minimum value is now being displayed
AVG :The Average value is now being displayed.
△REL :The reading is now under Relative Mode.
:The Battery is not sufficient for proper operation.

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○
1T1 K J type temperature sensor connector
○
2T2 K J type temperature sensor connector
○
3LCD display
○
4ON/OFF button
○
5HOLD button
○
6T1,T2,T1-T2 control button
○
7Relative readout button
○
8MAX MIN Average control button
○
9°C, °F control button
○
10 Digital output connector
○
12 AC power adapter connector
○
13 Tripod connector
○
14 Battery cabinet cover

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IV. Operation Instructions:
4.1 Power-Up
Press the ○
I key to turn the thermometer ON or OFF.
4.2 Connecting the Thermocouples
Plug the thermocouple into the input connectors.
4.3 Selecting the Temperature Scale
When the meter is first powered on, the default scale
is set at Celsius (°C). Change it to Fahrenheit (°F) by
pressing “ °C/°F ” button, Press it again to change
back to Celsius.
4.4 Selecting the Thermocouple Type
By default, when the meter is powered on, it defaults
to a K-Type, To change to a J-Type, press and hold
the “°C/°F” button while turning on the meter.
4.5 Data-Hold Operation
Hold the present reading and keep it on the display
by pressing the “HOLD” button. Release the data-hold
operation by pressing the “HOLD” button again.
When the meter is under Data Hold operation, the
“△REL”, and “ °C/°F ”buttons are disabled.
4.6 T1,T2,T1-T2 Display Control:
Select T1, T2 , or T1-T2 to show on the main display
by pressing the button. When T1 or T2 is
selected to show on the main display, the other
temperature will be shown on the secondary display.
Selecting T1-T2 will display the difference between
the T1 and T2 inputs.
4.7 Relative Operation for Main Display:
When the “△REL” button is pressed, the meter will

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memorize the present reading and will then
display the difference between the new reading and
the memorized data. Press the “△REL” button again
to exit the Relative operation.
4.8 MAX/MIN/AVG Operation for Main Display:
When the button is pressed, the meter will
enter the MAX/MIN mode. In this mode, the
maximum value, minimum value, and average value
of latest four (4) data samples is kept in the memory
simultaneously, and updated with every new data
sample.
When the MAX symbol is displayed, the Maximum is
shown on the display.
Press again, the MIN symbol will show on the
display along with the minimum reading.
Press again, the AVG symbol will show on the
display along with the average reading.
Press again, MAX, MIN and AVG will blink
together. This means that all data is updated in the
memory and the reading is the present temperature.
Press to circulate the display mode among
these options.
When the meter is in the mode, “△REL” and
“°C/°F ” are disabled.
To exit the MAX/MIN mode, press and hold
for two seconds.
4.9 Auto Power Off:
By default, when the meter is powered on, it is under
auto power off mode. The meter will power itself off
after 30 minutes if there are no key operations or

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TX RX GND
RS232 communication. To disable the auto power off
feature, press the “HOLD” button while turning on the
meter. Two successive beeps indicates the auto
power off feature is disabled.
4.10 Low Battery Condition
When the battery voltage falls below that required for
proper operation, the symbol will show on the
display. Replace the battery.
4.11 Digital Output:
The Digital Output is a 9600bps N 81 serial interface.
The RX is a 5V normal high input port.
The TX is a 5V normal high output port.
The commands for the Digital Output are listed below.
RS232 command Function Remarks
K(ASC 4BH) Ask for model No. Send 4 bytes
H(ASC 48H) Hold button
T(ASC 54H) TIMER button
M(ASC 4DH) AVG/MAX/MIN button
N(ASC 4EH) Exit AVG/MAX/MIN mode
R(ASC 52H) REL button
C(ASC 43H) ℃/℉ button
A(ASC 41H) Inquire all encoded data Send encoded 8
byte
•Command K:
Return 4 bytes. For example, when sends command
"K" to meter, it will return "3","0","3", ASCII(13) .
(0x13) represent T1,- 199.9°C, The total byte
number should be 7+1+7+1+5+chr(13)=22Bytes

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•Command T:
Equivalent to pushing the HOLD button.
•Command M:
Equivalent to pushing the HOLD and AVG/MAX/
MIN buttons and no message is returned.
•Command R:
Equivalent to pushing the REL button and no
message is returned.
•Command C:
Equivalent to pushing the ℃/℉ button and no
message is returned.
•Command A:
1nd BYTE:
The first byte is the start byte , its value is 2.
2nd BYTE:
bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0
C/F Low Bat Hold REL K/J MAX/AVG/MIN
bit 2 bit 1 bit0
0 0 0 Ɩnormal mode
0 0 1 ƖMAXIMUM mode
0 1 0 ƖMINIMUM mode
1 0 0 ƖAVG mode
1 1 1 Ɩcalculate MAX/MIN/AVG in
back-ground and lcd
"MAX""AVG""MIN" will flash.
bit3:1Ɩ0ƖK TYPE 1ƖJ TYPE
bit4:1ƖREL
bit5:1- HOLD 0Ɩnot HOLD
bit6:1ƖLOW BATTERY 0ƖBATTERY NORMAL
bit7:1Ɩ℃0Ɩ℉

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3nd BYTE:
bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0
point minus OL point minus OL
bit0:1Ɩmain window value is OL 0Ɩnot OL
bit1:1Ɩmain window value is minus, 0Ɩmain window
value is plus.
bit2:1Ɩ4th byte and 5th byte represent #### 0Ɩ4th byte
and 5th byte represent ###.#
bit3:1Ɩsub window value is OL 0Ɩnot OL
bit4:1Ɩsub window value is minus, 0Ɩsub window value
is plus.
bit5:1Ɩ6th byte and 7th byte represent #### 0Ɩ6th byte
and 7th byte represent ###.#
bit7 bit6:
00ƖMain window is T1-T2,sub window is T1
01ƖMain window is T1-T2, sub window is T2
10ƖMain window is T1, sub window is T2
11ƖMain window is T2, sub window is T1
4th BYTE:first two BCD code of main window value.
5th BYTE:last two BCD code of main window value
6th BYTE:first two BCD code of sub window value.
7th BYTE:last two BCD code of sub window value.
8th BYTE: The last byte is the end byte , its value is 3,
first and last byte are used to check frame
error.

MARTEL ELECTRONICS
PO Box 770, Londonderry, NH 03053 USA
Tel: [phone]
E-Mail: [email protected]
Web: http :/ / www.martelcorp.com 303-0107