GREISINGER GMH 3750 User manual

H49.0.02.6C-10
GHM GROUP - Greisinger
GHM Messtechnik GmbH | Hans-Sachs-Str. 26 | 93128 Regenstauf | GERMANY
Tel.: [phone] | [email protected] | www.greisinger.de
as of version 1.6 operating manual GMH 3750
Precision thermometer
for Pt100 4-wire temperature probes
WEEE-Reg.-Nr. DE 93889386
GMH 3700 Series
Pt100 Thermometer
Hochpräzision / High-Precision

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CONTENTS
1GENERAL NOTE......................................................................................................................................................3
2SAFETY......................................................................................................................................................................3
2.1 INTENDED USE.......................................................................................................................................................3
2.2 SAFETY SIGNS AND SYMBOLS................................................................................................................................3
2.3 SAFETY GUIDELINES..............................................................................................................................................3
3PRODUCT SPECIFICATION..................................................................................................................................4
3.1 SCOPE OF SUPPLY ..................................................................................................................................................4
3.2 OPERATION AND MAINTENANCE ADVICE..............................................................................................................4
4HANDLING................................................................................................................................................................5
4.1 DISPLAY ................................................................................................................................................................5
4.2 BASIC OPERATION.................................................................................................................................................5
4.3 CONNECTIONS .......................................................................................................................................................5
4.4 POP-UP CLIP...........................................................................................................................................................6
5START OPERATION................................................................................................................................................7
6CONFIGURATION...................................................................................................................................................7
7REMARKS TO SPECIAL FEATURES ..................................................................................................................8
7.1 DISPLAY RESOLUTION...........................................................................................................................................8
7.2 AVERAGE FILTER („T.AUG“)................................................................................................................................8
7.3 ALARM („AL.“) .....................................................................................................................................................8
7.4 USER SENSOR CURVE ('LIN USER').......................................................................................................................9
7.5 REAL TIME CLOCK („CLOC“)...............................................................................................................................9
8OPERATION OF LOGGER.....................................................................................................................................9
8.1 STORING SINGLE MEASUREMENTS („FUNC-STOR“) .............................................................................................9
8.2 AUTOMATIC RECORDING WITH SELECTABLE CYCLE TIME „FUNC CYCL“.......................................................10
9OUTPUT ...................................................................................................................................................................11
9.1 SERIAL INTERFACE..............................................................................................................................................11
9.2 ANALOGUE OUTPUT –SCALING WITH DAC.0 AND DAC.1................................................................................12
10 INPUT ADJUSTMENT........................................................................................................................................12
10.1 ZERO DISPLACEMENT ('OFFSET').....................................................................................................................12
10.2 SCALE CORRECTION ('SCALE').........................................................................................................................12
10.3 CALIBRATION SERVICES..................................................................................................................................12
11 PROBE CONNECTION......................................................................................................................................12
12 SOME BASICS OF PRECISION TEMPERATURE MEASURING..............................................................13
13 FAULT AND SYSTEM MESSAGES.................................................................................................................14
14 RESHIPMENT AND DISPOSAL.......................................................................................................................14
14.1 RESHIPMENT ....................................................................................................................................................14
14.2 DISPOSAL INSTRUCTIONS.................................................................................................................................14
15 SPECIFICATIONS...............................................................................................................................................15

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1 General Note
Read this document carefully and get used to the operation of the device before you use it. Keep this
document within easy reach near the device for consulting in case of doubt.
Mounting, start-up, operating, maintenance and removing from operation must be done by qualified, specially
trained staff that have carefully read and understood this manual before starting any work.
The manufacturer will assume no liability or warranty in case of usage for other purpose than the intended
one, ignoring this manual, operating by unqualified staff as well as unauthorized modifications to the device.
The manufacturer is not liable for any costs or damages incurred at the user or third parties because of the
usage or application of this device, in particular in case of improper use of the device, misuse or malfunction
of the connection or of the device.
2 Safety
2.1 Intended Use
The GMH 3750 is a precision thermometer for the measurement of the temperature with exchangeable 4-
wire Pt100 temperature sensors. With high resolution and precision temperature values can be measured
from -200 to 850 °C.
The device is to be protected against wetness and soiling and has to be stored and operated only within the
permissible environmental conditions and connection data (see “Specification”).
2.2 Safety signs and symbols
Warnings are labelled in this document with the followings signs:
DANGER
Caution! This symbol warns of imminent danger, death, serious
injuries and significant damage to property at non-
observance.

Attention! This symbol warns of possible dangers or dangerous
situations which can provoke damage to the device or
environment at non-observance.
Note! This symbol point out processes which can indirectly influence
operation or provoke unforeseen reactions at non-observance.
2.3 Safety guidelines
This device has been designed and tested in accordance with the safety regulations for electronic devices.
However, its trouble-free operation and reliability cannot be guaranteed unless the standard safety measures
and special safety advises given in this manual will be adhered to when using the device.
1. Trouble-free operation and reliability of the device can only be guaranteed if the device is not subjected to
any other climatic conditions than those stated under "Specification".
If the device is transported from a cold to a warm environment condensation may cause in a failure of the
function. In such a case make sure the device temperature has adjusted to the ambient temperature
before trying a new start-up.
2. If there is a risk whatsoever involved in running it, the device has to be switched off
immediately and to be marked accordingly to avoid re-starting.
Operator safety may be a risk if:
- there is visible damage to the device
- the device is not working as specified
- the device has been stored under unsuitable conditions for a longer time.
In case of doubt, please return device to manufacturer for repair or maintenance.
DANGER

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
3. When connecting the device to other devices the connection has to be designed most thoroughly as
internal connections in third-party devices (e.g. connection GND with protective earth) may lead to
undesired voltage potentials that can lead to malfunctions or destroying of the device and the connected
devices.
This device must not be run with a defective or damaged power supply unit.
Danger to life due to electrical shock!
4. Do not use these products as safety or emergency stop devices or in any other application
where failure of the product could result in personal injury or material damage.
Failure to comply with these instructions could result in death or serious injury and material
damage.
5. This device must not be used at potentially explosive areas! The usage of this device at
potentially explosive areas increases danger of deflagration, explosion or fire due to
sparking.
6. This device is not constructed for use in medical applications.
3 Product Specification
3.1 Scope of supply
The scope of supply includes:
device with 9V battery block
Operation manual
3.2 Operation and maintenance advice
Battery operation
If ‘bAt’ is shown in the lower display the battery has been used up and needs to be replaced. However,
the device will operate correctly for a certain time. If ‘bAt’ is shown in the upper display the voltage is too
low to operate the device; the battery has been completely used up.
The battery has to be taken out, when storing device above 50 °C.
We recommend taking out battery if device is not used for a longer period of time.
After recommissioning the real-time clock has to be set again.
•Mains Operation with power supply
When using a power supply please note that operating voltage has to be 10.5 to 12 V DC.
Do not apply overvoltage!! Cheap 12V-power supplies often have excessive no-load voltage.
We, therefore, recommend using regulated voltage power supplies.
Trouble-free operation is guaranteed by our power supply GNG10/3000.
Prior to connecting the power supply to the mains make sure that the operating voltage stated at the
power supply is identical to the mains voltage.
Treat device and sensor carefully. Use only in accordance with above specification. (do not throw, hit
against etc.). Protect plug and socket from soiling.
To disconnect temperatur sensor plug do not pull at the cable but at the plug.
When connecting the probe the plug will slide in smoothly if plug is entered correctly.
Selection of Output-Mode: The output can be used as serial interface or as analogue output. This
choice has to be done in the configuration menu.
_DANGER
_DANGER
DANGER
DANGER

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4 Handling
4.1 Display
1 Maindisplay: Currently measured temperature
2 Secondary display: Display of min, max or hold values
Special display elements:
3Min/Max/Hold: shows if a min., max. or hold value is
displayed in the auxiliary display
4“Offset“ arrow: indicates that zero point offset is activated
5„Corr“ arrow: indicates that a scale correction is activated
6„Logg“ arrow: Shown if logger function is selected,
flashes if cyclic logger is running
7„Alarm“ arrow: Flashes if alarm is present
4.2 Basic Operation
On / Off
+
min/max at measure:
press short: shows the min./max. value
press again: hides min./max. value
press 2 sec.: clears particular value
Function only during configuration:
Selection of menu-parameter
Set/Menu:
press short: invokes configuration menu
Store/Quit:
press short: hold-function, the last measuring
value will be held in the secondary
display.
at active logger: invokes logger functions
at menu: acknowledge setting, return to
measurement
4.3 Connections
Output: Connection for el. Isolated interface adapter
or for analog output (please refer to chapter
9)
Probe connection: 4 pole Mini-DIN-Socket, for Pt100
4-wire probes
Power supply: the mains adapter socket is located at the left side of the device.
1 2 3
4 5 6
ON
OFF max Tara
Storemin
Set
Menu Quit
1 2 3
4 5 6
ON
OFF max Tara
Storemin
Set
Menu Quit

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4.4 Pop-up clip
Handling:
•Pull at label “open” in order to swing open the pop-up clip.
•Pull at label “open” again to swing open the pop-up clip further.
Pop-up clip closed
Pop-up clip at position 90°
Pop-up clip at position 180°
Function:
• The device with a closed pop-up clip can be plainly laid onto a table or attached to a belt, etc.
• The device with pop-up clip at position 90° can be set up on a table, etc.
• The device with pop-up clip at position 180° can be suspended from a screw or the magnetic holder
GMH 1300.
Device attached to a belt
Device set up on a table
Device suspended from
magnetic holder
GMH 1300

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5 Start Operation
Connect Temperature probe, turn on device via key.
After segment test the device displays some configuration:
• If the logger function is not off the time of the integrated clock will shortly be displayed.
• If a zero point adjustment was carried out the display shows shortly „nuLL Corr“.
After changing the battery the clock-setting menu is activated automatically (‚CLOC‘). Check the clock
and adjust, if necessary (p.r.t. chapter 6).
After that the device is ready for measuring.
6 Configuration
To change device settings, press Menu (key 4) for 2 seconds. This will call the configuration menu (main
display: „SEt“ or “rEAd LoGG”).
Pressing key Menu changes between the menus, pressing ( (key 3) jumps to the referring parameters,
which can be selected with key ( (key 3).
The parameters can be changed with (key 2) or (key 5).
Pressing Menu again jumps back to the main configuration menu and saves the settings.
Quit (key 6) finishes the configuration and returns to standard measuring operation.
Menu(*1)
Parameter/Values(2*)
Meaning
p.r.t.
‚Menu‘

or 
Read Logg: single value-logger read out
(only when data existing! Please refer to chapter 12)
8
Set Configuration: Generic Settings
°C:
All temperature values are in degrees Celsius
*
°F:
All temperature values are in degrees Fahrenheit
0.1° / 0.01°:
Resolution 0.1° / 0.01°
*
7.1
Auto:
Resolution is selected automatically
E.751
characteristic curve according to EN60751
*
7.4
USEr
User sensor curve (Predefined to EN60751 values,
changeable by software GMHKonfig)
-2.50...2.50°C /
-4.50...4.50°F
Zero correction
*
10.1
oFF:
Zero displacement inactive (=0.0°)
-2.000...2.000:
Scale correction [in %]
*
10.2
oFF:
Scale correction factor inactive (=0.000)
1...30:
Average filter (period in seconds)
*
7.2
oFF:
Average filter inactive
1...120
Power-off delay in minutes. Device will be
automatically switched off as soon as this time has
elapsed if no key is pressed or no interface
communication takes place
oFF
Power-off function inactive (continuous operation)
oFF:
No output function
9
SEr:
Output is serial interface
dAC:
Output is analogue output
01,11..91
Base address of device for interface communication
9.1
-200..850°C /
–328...1562°F
Zero point of analogue output: Temperature at
which the analogue output potential should be 0V
9.2
1 2 3
4 5 6
ON
OFF max
Store
CAL
min
Set
Menu Quit

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-200..850°C /
-328...1562°F
Scale of analogue output : Temperature value at
which the analogue output potential should be 1V
9.2
Set Alarm: Setting of Alarm Function
On / No.So
Alarm on with horn-sound / Alarm on without horn-
sound
7.3
OFF
no alarm function
-200°C ...AL.Hi
Min alarm rail (not when AL. oFF)
AL.Lo ... 850°C
Max alarm rail (not when AL. oFF)
Set Logger: Setting of Logger Function
CYCL
Cyclic: logger function cyclic logger
*
8
Stor
Store: logger function individual value logger
OFF
No logger function
0:01... 60:00
Cycle time of cyclic logger [minutes:seconds]
*
8
Set Clock: Einstellen der Echtzeituhr
HH:MM
Clock: Setting of time hours:minutes
7.4
YYYY
Year
TT.MM
Date: day.month
(*) If the logger memory contains data already, the menus/parameters marked with (*) can not
be invoked! If these should be altered the logger has to be stopped and the memory has to
be cleared before!
Hint: Restoring of ex-works settings
The settings will be set to the settings ex works, if keys ‘Set‘ and ‘Store‘ are pressed simultaneously
for more than 2 seconds.
7 Remarks To Special Features
7.1 Display Resolution
Standard setting: 'Auto', i.e. the device automatically switches over to the optimum resolution between .01°
and 0.01°.
If temperatures to be measured are near the switching threshold, a fixed resolution may be better, e.g. for
easy manual recording. In such a case please set the optimum resolution to the desired value.
7.2 Average filter („t.AuG“)
The filter forms the arithmetic floating average over the entered time. The displayed value will be
correspondingly slower in this case.
7.3 Alarm („AL.“)
There are three possible settings:
Alarm off (AL. oFF), on with horn sound (AL. on), on without horn sound (AL. no.So).
Following conditions will display an alarm, when the function is activated (on or no.So):
-Value is below lower (AL. Lo) or above upper alarm rail (AL.Hi).
-Sensor error
-Low battery (bAt)
-Err.7: System error (always with sound)
In case of an alarm and when polling the interface the “prio”-flag is set in the returned message.

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7.4 User Sensor Curve ('Lin USEr')
By means of this function besides the standard conversion of resistance to temperature following
EN60751(Lin E.751) also other curves can be used. The user sensor curve can be read and edited by the
configuration software GMHKonfig. The standard setting ex works is also set to the EN60751 data. The
curve is defined by a table with two columns (input resistance[Ohm]/output temperature [°C]) with 50 rows.
Info: the sensor curve following EN60751 uses the international temperature scale ITS90 and following
formulas:.
Temperatures < 0°C:
Rneg(T) := 100 · [1 + 3.9083·10-3·T –5.775·10-7·T2 –4.183·10-12·(T –100)·T3]
Temperatures >= 0°C:
Rpos(T) := 100 · (1 + 3.9083·10-3·T –5.775·10-7·T2)
Please notice: Temperature measurements with the user sensor curve are allowed only within the
temperature range which has been used to generate the user sensor curve.
Measuring with activated user sensor curve beyond the checked temperature range may lead to
larger errors. Therefore the sensor curve acc. to EN 60751 (Lin E.751) has to be used for
temperature measurements beyond the checked temperature range.
7.5 Real Time Clock („CLOC“)
The real time clock is used for the logger function: Recorded values are also containing the point of time,
when they were measured. Please check the settings when necessary.
If the battery was replaced the referring menu ‚CLOC‘ will automatically be started
8 Operation Of Logger
The device supports two different logger functions:
„Func-Stor“: manual recording via keypress “Store” (key 6).
„Func-CYCL“: automatic recording with the selected recording interval/cycle
The logger records 1 measurement result each time
The data set consists of: - measuring value at time of recording
- time and date of recording
For the read out and evaluation of the data the software GSOFT3050 (V1.7 or higher) has to be used. The
software also allows easy configuration and starting of the logger.
When the logger is activated (Func Stor or Func CYCL) the hold function is no longer available, key 6 is
solely used for the operation of the logger functions.
8.1 Storing Single Measurements („Func-Stor“)
a) Record Measuring:
If the logger function “Func Stor” was activated (see chapter 6“Configuration”), up to 99 measuring data
sets can be recorded manually.
Press shortly: Data set will be recorded (“St. XX” will be shown shortly. XX is the number of the
data set)
If the logger memory is full, the display will show:
b) Viewing Recorded Measurings:
Stored data sets can be either read out via PC Software GSOFT3050, or be viewed in the display directly.
Press for 2 seconds: The display will show:
Please note: ”rEAd Logg” only appears, if there are already data stored! If memory is empty, the
configuration menu will show.
Press shortly: Changing between measuring value and date+time of data set
or
Changing between the data sets
Exit logger data display

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c) Clear recorded measurings:
If there are already data sets stored, these can be deleted via the store key:
Press for 2 seconds: Calling of clear-Menu
Change selection by: or :

Clear nothing (cancel menu)

Clear all recordings

Clear the last recording
Stores the settings
8.2 Automatic Recording With Selectable Cycle Time „Func CYCL“
If the logger function “Func CYCL” was activated (see chapter 6 “Configuration”), and the logger was started,
it automatically records data sets at intervals of the selected logger cycle time
The logger cycle time is selectable from 1s to 60min (see chapter 6 “Configuration”).
Max. number of measurings: 16384
a) Starting a recording:
press for 2 seconds: the recording will be started.
Each recodring is signales with a short diplay of ‘St.XXXXX’. XX is the number of the data set.
If the logger memory is full, the display will show
b) Stop the recording:
Press for 2 seconds: If a recording is running, the Stop menu will be shown
Change selection by: or :
Do not stop the recording
Stop the recording
Stores the settings
Note: If you try to switch off the instrument in the cyclic recording operation, You will be asked
automatically if the recording should be stopped.
The device can only be switched off after the recording has been stopped!
The Auto-Power-Off-function is deactivated during recording!
c) Clear recorded measurings:
Press for 2 seconds: If logger data are present and the recording was stopped, the
clear menu will be shown
Change selection by: or :
Clear nothing
(cancel menu)
Clear all recordings
Stores the settings