UNI-T UT321, UT322, UT323, UT325 Operating Manual

Table of Contents

4
7
8
10
12
16
16
17
17
18
18
18
19
19
19
20
21

Title Page

Safety Information
Getting Started
Components
Display Elements
Buttons
Using the Thermometer
Changing Setup Options
Entering and Exiting Setup
Changing the Logging Interval
Changing the Thermocouple Type
Changing the Offset (T1)
Changing the Offset (T2)
Sleep Mode
Changing the Line Frequency
Setting the Time
Setting the Low Limit Alarm (Lo)
Setting the High Limit Alarm (Hi)

1

Model UT321/322/323/325: OPERATING MANUAL

23
23
24
25
25
26
26
26
26
27
27
27
28
29
29
30
31
31

Title Page

Measuring Temperatures
Connecting a Thermocouple
Displaying Temperatures
Holding the Displayed Temperatures
Turning on and off of display backlight
Viewing the MIN, MAX, and AVG Readings
Using the Offset to Adjust Probe Errors
Over Limit Alarm
Over Limit Signal Output
Debug
Using Memory
Starting and Stopping Logging
Viewing Logged Readings
Clearing Memory
Communicating with a PC

Enabling or Disabling Over Limit Signal Output
Enabling or Disabling Normal Temperature Compensation (NTC)
Enabling or Disabling Debug

Model UT321/322/323/325: OPERATING MANUAL

2

Maintenance
Replacing the Battery
Cleaning the Case
Specifications
Environmental
General
Electrical

Title Page

32
32
32
33
33
33
33

Model UT321/322/323/325: OPERATING MANUAL

3

Safety Information

The Uni-Trend Model UT321, UT322, UT323 and UT325 Thermometers (‘the
thermometer) are microprocessor-based, digital thermometers designed to use
external J-, K-, T-, E-, R-, S- and N- type thermocouples (temperature probes) as
temperature sensors.

UT321: T1, suitable for K-, J-, T- and E- type thermocouples
UT322: T1 and T2, suitable for K-, J-, T- and E- type thermocouples
UT323: T1, suitable for K-, J-, T-, E-, R-, S- and N- type thermocouples. Equipped
with over limit alarm, over limit signal output and user self-debug features.
UT325: T1 and T2, suitable for K-, J-, T-, E-, R-, S- and N- type thermocouples.
Equipped with over limit alarm, over limit signal output and user self-debug features.

Use the thermometer only as specified in this manual. Otherwise, the protection
provided by the meter may be impaired.

Model UT321/322/323/325: OPERATING MANUAL

4

Refer to safety information in Table 1 and the international symbols in Table 2.

Table 1. Safety Information

Before using the thermometer inspect the case. Do not use the thermometer if it
appears damaged. Look for cracks or missing plastic. Pay particular attention to the
insulation around the connectors.
Disconnect the thermocouple(s) from the thermometer before opening the case.
Replace the batteries as soon as the battery indicator ( ) appears. The possibility
of false readings can lead to personal injury.
Do not use the thermometer if it operates abnormally. Protection may be impaired.
When in doubt, have the thermometer serviced.
Do not operate the thermometer around explosive gas, vapor, or dust.
Do not apply more than the rated voltage, as marked on the thermometer (30V|),
between the thermocouple(s), or between any thermocouple and earth ground.
When potential differences are anticipated between the thermocouples, use electrically
insulated thermocouples.
When servicing the thermometer, use only specified replacement parts.
Do not use the thermometer with any part of the case or cover removed.

Warning

A warning identified conditions and actions that pose hazards to the user. To avoid
electrical shock or personal injury, follow these guidelines:

Model UT321/322/323/325: OPERATING MANUAL

5

Caution

A caution identifies conditions and actions that may damage the meter or the
equipment under test.

Use the proper thermocouples, function, and the range of your thermometer.
When carrying two thermocouples measurement, make sure there are no
potential differences between two thermocouples.
Do not attempt to recharge the battery.
Match the + and – polarities of the battery with the battery case.

Table 2. International Symbols
Refer to the manual for information about this feature
Complies with European Union directives
Battery

Model UT321/322/323/325: OPERATING MANUAL

6

Getting Started

Everything in this Users Manual applies to all Models of UT321, UT322, UT323 and
UT325 unless otherwise indicated.

To become familiar with the thermometer, study the following:

Figure 1 and Table 3 describe the components
Figure 2 and Table 4 describe the display.
Figure 3-a and 3-b and Table 5 describes the functions of the buttons.

Then read the following sections.

Model UT321/322/323/325: OPERATING MANUAL

7

Figure 1. Components

Model UT321/322/323/325: OPERATING MANUAL

8

Table 3. Components

Display
Buttons
Thermocouple T1 input
Thermocouple T2 input (UT323 and UT325 only)
USB Port
SIGN Port - Over Limit Signal Output (UT323 and UT325 only)
NTC
Battery Door
9V battery (6F22 )

1
2
3
4
5
6
7
8
9

Model UT321/322/323/325: OPERATING MANUAL

9

Model UT321/322/323/325: OPERATING MANUAL

10

Table 4. Display Elements

Setup is in progress when the icon blinks
Display readings of maximum, minimum and average
Data Transferring is in progress
Logged readings are displayed when the icon blinks
Low battery. Replace the battery
The thermocouple type
The temperature units
Secondary Display 1
Under Calibration mode when the icon blinks. The displayed reading is fixed.
Secondary Display 2
The thermocouple measurement includes an offset. See “Changing Setup

Options”
Readings are being logged when the icon blinks
Primary Display
The displayed readings do not change
The symbol of display backlight

1
2
3
4
5
6
7
8
9

10
11
12

13
14

Model UT321/322/323/325: OPERATING MANUAL

11

Figure 3-a UT321 and UT323 buttons set

Model UT321/322/323/325: OPERATING MANUAL

12

Figure 3-b UT322 and UT325 button set

Model UT321/322/323/325: OPERATING MANUAL

13

Table 5. Buttons

Press to turn the thermometer on or off
Press to turn the display backlight on and off.
Press to freeze or unfreeze the displayed readings

Press to switch between Celsius (ºC), Fahrenheit(ºF), and Kelvin (K)
Press to step through the maximum, minimum, and average readings.

Press and hold to turn off this display.
Press to step through K-, J-, T-, E- (R-, S-, N-) type thermocouple.

Press to toggle showing the T1, T2 and T1-T2 (differential temperature
measurement) in the primary or secondary display 1

Press to enter USB mode and the USB icon blinks. Press again to exit
USB mode.

Press to start or stop logging.
(See “Using Memory - Starting and Stopping Logging”.)

Press to show logged readings
Press again to stop.

MAX MIN

HOLD

ºC ºF

SEND

STORE

RECALL

Model UT321/322/323/325: OPERATING MANUAL

14

Press to start or exit Setup.
Press to scroll the Setup option you want to change
(See “Changing Setup Options”)

After entering the Setup mode, press to increase the displayed setting.
(See “Changing Setup Options”)

After entering the Setup mode, press to decrease the displayed setting.
(See “Changing Setup Options”)

Confirm button.
(See “Changing Setup Options”)

Table 5. Buttons

ENTER

SETUP

Model UT321/322/323/325: OPERATING MANUAL

15

Using the Thermometer

1) Plug the thermocouple(s) into the input connector(s).

2) Press the power button to turn on the thermometer.

3) Set the type of thermocouple(s) to be same of the type plug into the input
connector(s).

If no thermocouple is plugged into the selected input or the thermocouple is “open”
and the over-range positive deviation is too big, the display shows “_ _ _ _“.

Changing Setup Options

Use Setup to change the following settings:
Logging interval Thermocouple type Offset (T1) Offset (T2) (UT322 and
UT325 only) Sleep Mode Line Frequency Time (S-T) Low Limit Alarm
(Lo) (UT323 and UT325 only) High Limit Alarm (Hi) (UT323 and UT325 only)

Over Limit Signal Output (SI) ON/OFF (UT323 and UT325 only) Normal
Temperature Compensation (NTC) ON/OFF DEBUG ON/OFF (UT323 and UT325
only) Save setting and return to normal measurement mode.

Model UT321/322/323/325: OPERATING MANUAL

16

When the thermometer is in Setup mode, the display shows and blinks SETUP.

Press SETUP to start or exit Setup.
Press SETUP to scroll the Setup option you want to change after

The logging interval determines how often the thermocouple stores logged readings
in memory. You choose the length of the logging interval. See “Using Memory”.

Press SETUP until the display shows INTERVAL.
The thermometer stores logged readings at the end of each logging interval. You can

select a logging interval by pressing or . Holding down or causes the number
to change more quickly. The maximum interval is 59:59 and the minimum interval
is 00:00. When the logging interval is 00.00, you need to store the readings manually
as the auto store feature will be disabled.

Model UT321/322/323/325: OPERATING MANUAL

17

1. Press SETUP until the display shows TYPE.

2. Press or to select the thermocouple type you want including K-, J-, E- type
(UT323 and UT325 have extra R-, S- and N- type).

1. Press SETUP until the display shows OFFSET and T1

2. Press or until the display shows the correct reading. The offset readings
range

1. Press SETUP until the display shows OFFSET and T2

2. Press or until the display shows the correct reading. The offset readings
range

Model UT321/322/323/325: OPERATING MANUAL

18

Model UT321/322/323/325: OPERATING MANUAL

19

Model UT321/322/323/325: OPERATING MANUAL

20

Below table shows the measuring range of each type of thermocouple

K type: -200.0ºC to +1372ºC (-328.0 ºF to +2501 ºF)
J type: -210.0ºC to +1200ºC (-346.0 ºF to +2192 ºF)
T type: -250.0ºC to +400.0ºC (-418.0 ºF to +752.0 ºF)
E type: -150.0ºC to +1000ºC (-238.0 ºF to +1832 ºF)

Model UT321/322/323/325: OPERATING MANUAL

21

For example:

The maximum reading of the high alarm of K type is +1372ºC.
The minimum reading of the high alarm of K type is either the low alarm

reading plus 1 or -200ºC.

Below table shows the measuring range of each type of thermocouple

K type: -200.0ºC to +1372ºC (-328.0ºF to +2501ºF)
J type: -210.0ºC to +1200ºC (-346.0ºF to +2192ºF)
T type: -250.0ºC to +400.0ºC (-418.0ºF to +752.0ºF)
E type: -150.0ºC to +1000ºC (-238.0ºF to +1832ºF)

Model UT321/322/323/325: OPERATING MANUAL

22

Model UT321/322/323/325: OPERATING MANUAL

23

Model UT321/322/323/325: OPERATING MANUAL

24

Measuring Temperatures

Thermocouples are colour coded by type based on the North American ANSI Colour
Code:

Type Colour Type Colour

J Black R Green
K Yellow S Green
T Blue N Orange
E Purple

1. Plug a thermocouple into the input connector(s).

2. Set the thermometer for the correct thermocouple type.
To change the thermocouple type, see “Changing Setup Options”.

Model UT321/322/323/325: OPERATING MANUAL

25

1. Press ºC ºFK to select the correct temperature scale.

2. Hold or attach the thermocouple(s) to the measurement location.
The temperature reading appears in the selected display

1. Press HOLD to freeze the readings on the display. The display shows HOLD.

2. Press HOLD again to turn off the HOLD function.

1. Under temperature measurement mode, press to turn the display backlight on.

2. Press

again to turn off the display backlight. The display backlight will not

automatically off.

1. Press MIN MAX to step through the maximum (MAX), minimum (MIN), or the
average (AVG) readings.

2. Press and hold MIN MAX to exit MIN MAX mode.

Model UT321/322/323/325: OPERATING MANUAL

26

Use the offset option in Setup to adjust the thermometer’s readings to compensate
for the errors of a specific thermocouple.

1. Plug the thermocouple into the input connector.

2. Place the thermocouple in a known, stable temperature environment (such
as an ice bath or a dry well calibrator).

3. Allow the readings to stabilize.

4. In Setup change the offset until the display reading matches the calibration
temperature. (See “Changing Setup Options.”)

Setting the low alarm and high alarm limit at the SETUP mode, the thermometer
beeps when the measured temperature is higher or lower than the pre-set limit. (See
“Changing Setup Options.”)

Setting the low and high limit signal output at the SETUP mode, the SIGN port output
the corresponding signal when the measured temperature is higher or lower than the
pre-set limit. (See “Changing Setup Options.”)

Model UT321/322/323/325: OPERATING MANUAL

27

After entering the Debug mode, you can self-debug. Below is the procedure:

K- and J- type: -180ºC, 0ºC and 900ºC
T type: -180ºC, 0ºC and 400ºC
E type: -140ºC, 0ºC and 900ºC
R- and S- type: 0ºC and 1200ºC
N type: -180ºC, 0ºC and 1200ºC
Remark: 0ºC only need to debug k type.

Model UT321/322/323/325: OPERATING MANUAL

28

Remark:
The corresponding table between temperature and voltage refer to BS EN 60584-

1:1996. Before carrying out debug, to ensure your standard source has enough
accuracy. It is at your own responsibility, if the thermometer has too big accuracy
deviation is caused by the standard source does not have enough accuracy.

Using Memory

During a logging session, the thermometer stores logged readings in its memory.
The thermometer stores 00-99, total 100 sets of temperature readings. The stored

readings are from primary display.

1. Set the logging interval. (See “Changing Setup Options.”)

2. Press STORE to start logging.
The display blinks DATA.

3. Press STORE again to stop logging.

4. If you selected a manual logging interval, set the logging interval as 00:00. Press
ENTER each time you want to store logged readings in memory. The secondary

Model UT321/322/323/325: OPERATING MANUAL

29

display 1 shows the logged reading. Each presses of ENTER will automatically
store the logged readings in the next memory location. Press or could
change the memory location, the empty location shows “- - - - - ”.

5. If you selected an auto logging interval, set the logging interval not 00:00. After
entering logging mode, the secondary display 2 shows “:” Press ENTER to start
storing readings in sequence according to the pre-set logging interval, the “:”
blinks. Press ENTER again to pause auto logging, the “:” stop blinking. Press
ENTER again to resume logging, the “:” blinks again.

Model UT321/322/323/325: OPERATING MANUAL

30

1. Press STORE to enter logging mode, the display shows DATA and blinks.

2. Press and hold down STORE 2 seconds, the display shows CLR.

3. Press ENTER to delete all the logged readings from memory. It is not possible
to delete the logged readings one by one.
The display then shows “----“

Communicating with a PC

You can transfer the contents of the thermometer’s memory to a PC using the
included Software.

Press SEND button and USB blinks on the display. It means the thermometer and
the PC are connected correct. Details refer to the Installation Guide file in the
Software.

Under the influence of radiated Radio-Frequency electromagnetic Field phenomenon,
the captioned model have a measurement error, it will be back to normal when the
interference is removed.

Model UT321/322/323/325: OPERATING MANUAL

31

Maintenance

Replace the batteries as soon as the battery indicator appears. The possibility
of false readings can lead to personal injury.

1. Turn off the thermometer.

2. Loosen the screw and remove the battery door.

3. Replace 1 piece of 9V battery (6F22). Replace the battery door and tighten the
screw.

Use soap and water or mild commercial cleaner. Wipe with a damp sponge or soft
rag.

Model UT321/322/323/325: OPERATING MANUAL

32

Specifications

Operating Temperature
Storage Temperature

Humidity

-10ºC to 50ºC
(14ºF to 122ºF)

-40ºC to + 60ºC
(-14ºC to +140ºC)
Non condensing <10ºC (<50ºF)
95% RH: 10ºC to 30ºC (50¨ºF to 86ºF)
75% RH: 30ºC to 40ºC (86ºF to 104ºF)
45% RH: 40ºC to 50ºC (104ºF to 122ºF)

Certification
Safety

EN61326: 2006, EN55022: 2006 and EM55024: 1998+A1+A2

Model UT321/322/323/325: OPERATING MANUAL

33

Function UT321 UT322 UT323 UT325 Input
Protection

Type

Input

Measurement
Range

Display
Resolution

Measurement

Accuracy

K, J, T, E K, J, T, E, R, S, N

T1 T1, T2 T1 T1, T2

K type: -200.0ºC to +1372ºC (-328.0 ºF to +2501 ºF)

J type: -210.0ºC to +1200ºC (-346.0 ºF to +2192 ºF)

T type: -250ºC to +400.0ºC (-418 ºF to +752.0 ºF)

E type: -150.0ºC to +1000ºC (-238.0 ºF to +1832 ºF)

0.1ºC ºF/K…. (<1000) (T type below -200ºC and R
type, S type is 1ºC ºF/K)

1.0ºC ºF/K…. (>1000)

K-,J-,T-, E- ty p e:
±(0.2%+0..6ºC(1.2ºF))

R,S

type: ±(0.2%+2ºC(4ºF))

N type: ±(0.2%+1.5ºC(3ºF))

±(0.5%+0.8ºC(1.6ºF))

30V

Model UT321/322/323/325: OPERATING MANUAL

34

Function UT321 UT322 UT323 UT325 Input
Protection

Measurement
Accuracy

30V

Below -10ºC: add 0.5ºC
Below -200ºC, add +2ºC
Type T Below -200ºC: for reference only.

50 times per second, Updates 2-3 times per second
Relative Time
0 ~ 99 sets
Logging Interval, Thermocouple Type, Offset (T1),

Offset (T2) (UT322 and UT325 only), Sleep Mode,
Line Frequency, Time, High/Low Limit (UT323 and
UT325 only), Over Limit Signal Output (UT323 and
UT325 only), Normal Temperature Compensation,
Debug (UT323 and UT325 only)

N/A Yes
N/A Yes
One piece of 9V (NEDA1604 or 6F22 or 006P)

Sampling Rate
Time
Data Store

Setup

Over Limit Alarm
Over Limit Signal

Power

Model UT321/322/323/325: OPERATING MANUAL

35

** END **

Accuracy is specified for ambient temperatures between 18ºC(60ºF)and 28ºC (82ºF)
for a period of 1 year, operating temperatures: -10ºC ~ 50ºC (14ºF ~122ºF). The
above specifications do not include thermocouple error,probe tolerance is not included
in above technical index.

Model UT321/322/323/325: OPERATING MANUAL

36

Copyright 2008 Uni-Trend Group Limited.

All rights reserved.
Manufacturer:

Uni-Trend Technology (Dongguan) Limited
Dong Fang Da Dao
Bei Shan Dong Fang Industrial Development District
Hu Men Town, Dongguan City
Guang Dong Province
China
Postal Code: 523 925

Headquarters:
Uni-Trend Group Limited
Rm901, 9/F, Nanyang Plaza
57 Hung To Road
Kwun Tong
Kowloon, Hong Kong
Tel: [phone]
Fax: [phone]
Email: [e-mail]
http://www.uni-trend.com

Model UT321/322/323/325: OPERATING MANUAL

37