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Graphtec America GL840-M - Isolated/Universal Input, Standalone Multi-Channel Datalogger

Isolated/Universal Input, Standalone Multi-Channel Datalogger

Graphtec America

Category : Data Acquisition

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Users Manual Datasheet


GL840 expands to two models for application specific use

  • GL840-M Multi-Inputs Model
    Suitable for temperature measurement in multiple channels
  • GL840-WV Withstand-Voltage Model
    Suitable for voltage measurement in battery pack or high-precision temperature measurements.

Wireless measurement using wireless LAN (option) 

Wireless LAN option enables the wireless communication with other device. When the GL840 is set as a station, PC and smart devices will be able to access the WLAN unit directly.


Useful Functions

Various functions, such as a bar chart data display, alarm output function, navigation function, and networking features, are available in the GL840 to assist be conveniently used.


Built-in 4GB Flash Memory with SD Card Support

The new GL series enables reliable long term measurment with its built-in 4GB flash memory and SD card slot for external storage devices.

* The built-in Flash memory is available for units with the following serial numbers, please contact your local representative for the details.


Model Destination
America Europe Asia
GL840-M C6051xxx C6041xxx C6041xxx
GL840-WV C6052xxx C6052xxx C6052xxx


Three Types of Input Systems Enable Measurement of Various Signals

Along with the basic analog signal, Logic/Pulse, and digital sensors can be all connected to monitor a variety of measurements.


Combining GL100-WL and GL840

GL100-WL can now be connected to the GL840 as a remote sensor using the WLAN feature. GL840 supports up to five units of the GL100-WL.


Maximum Sampling Interval up to 10ms

Provides faster sampling rate 10ms for voltage measurement.

Graphtec America GL840-M - Isolated/Universal Input, Standalone Multi-Channel Datalogger

Three types of input system enable to measure various phenomena

Input system 1 : Multifunction analog input ports

Contains a highly isolated input system which ensures that signals are not corrupted by noise from other channels. The GL840's inputs are suitable for combined measurements from voltage, temperature, humidity, logic, and pulse signals.
The standard configuration has 20 analog input channels. It is expandable to 200 channels by adding optional 20 channels extension terminal base unit (B-566) and input terminal units (B-564 or B-565).

Withstand voltage & Accuracy Multi-input type (B-564) Withstand-voltage type (B-565)
Voltage Input voltage range 20 mV to 100 V 20 mV to 100 V
Max. voltage (Input - GND) 60 Vp-p 300 Vp-p
Temp. Thermocouple R, S, B, K, E, T, J, N, W (WRe5-26)
RTD (Resistance Temp. Detector) Pt100 (IEC751), Pt1000 (IEC751), JPt100 (JIS)
Accuracy Voltage ± 0.1% of F.S. ± (0.05% of FS + 10μV)
Temperature* ± 1.55 ºC ± 1.1 ºC

* Accuracy rating for K-type thermocouple at 100˚C includes reference junction compensation. Accuracy varies by temperature levels and thermocouple types.

The following shows how a standard configuration is expanded to more than 40 channels


Configuration for additional channels

Number of channels

20 channels

40 channels

100 channels

200 channels

GL840 unit (GL840-M or GL840-WV)

1 set

1 set

1 set

1 set

Connection cable (B-567-05 or -20)


1 pc

1 pc

1 pc

Terminal base (B-566)


2 sets

5 sets

10 sets

Input terminal (B-564 or B-565 )


1 set

4 sets

9 sets


Offers longer cable for the input terminals

Input terminal blocks can be connected directly (in daisy chain), or using the B-565 cable(s). This allows the input terminals to be placed in separate locations according to the need of the application.

The input terminal unit and the GL840 main body can be extended by using an extended connections cable.

*If the signal is affected by noise, it may be required to use a slower sampling.


Input system 2 : Support digital sensors

Digital sensors and input terminal/adapters for the GL100 connects to the GL840 directly



Input system 3 : 4 channels of Logic/Pulse inputs

Supports 4-channels logic or pulse signal inputs. Pulse mode allows cumulative, instant, or rotational values for industrial measurement capability with speed and flow.



Maximum sampling interval of up to 10ms

Provides faster sampling rates for voltage measurements. Up to 10ms sampling speed is achievable when limiting the number of channels in use.

Sampling Interval Number of channels Measuring
Voltage Temperature
10ms 1 -
20ms 2 -
50ms 5 -
100ms 10
200ms 20
500ms 50
1s 100
2s 200


Built-in 4GB Flash memory with SD card support

The new GL series enables reliable long term measurment with its built-in 4GB flash memory and SD card slot for external storage devices. The SD card slot supports an SDHC memory card of up to 32GB.

The captured data can be stored in GBD (Graphtec binary data) or CSV file format.

Capturing time* (when all 20 analog channels are being used with Logic/Pulse inputs turned off.)

Sampling GBD format CSV format
10ms 31 days 3 days
50ms 77 days 11 days
100ms 95 days 16 days
200ms 108 days 21 days
500ms 270 days 54 days
1s Over 365 109 days
10s Over 365 Over 365

*Figures are approximate. File size of captured data is 2GB in GBD or CSV file format on this chart.

Sampling interval is limited by the number of channels in use. (10ms:1ch, 50ms:5ch, 100ms:10ch)

Limited sampling speed is available when digital sensors and GL100-WL are used as a remote monitoring device.

Ring Capture Function

The most recent data is saved when the memory is configured in ring memory mode. (Number of capturing data is 1000 to 2000000 points)

Relay Capture Function

Data is continuously saved to multiple files up to 2GB without losing any data until capturing is stopped when the memory is configured in the relay mode.

Hot-Swapping the SD Memory Card

SD card can be replaced during data capturing when the sampling interval is 100ms or slower.



Useful Functions

Displays the data by a bar chart (in firmware ver.1.10 or later)

The integrated data that is measured by the digital sensors can be displayed by a bar chart in the GL840 series.


Available GS sensors Measurement Unit
GS-TH (Temp/Humidity) sensor Integrated temperature ℃h
GS-DPA-AC adapter with GS-Acxxx sensor (AC current/power) Integrated power kWh
GS-LXUV (Illuminance/UV) sensor Integrated illuminance lxh or klxh
Integrated UV mW/cm2h


Alarm Output Function

Alarm signals can be placed using the four channel alarm output ports based on set conditions for each channel.

* Optional cable (B-513) is required.

USB Drive Mode

USB drive mode function enables data to be transferred to the PC from GL840 by drag & drop feature.

Navigation Function

Simple to use navigation screen allows setting operation for measurement and wireless LAN adapter.

Large Easy-to-Read 7-Inch Wide Color LCD

Monitoring data can be displayed in waveform or digital form. Parameter settings can be displayed on the screen.

3 Types of Power Source

Choose from AC power supply, DC supply* or the rechargeable battery pack.*
* Optional accessories (B-514 or B-569) are required.

Networking Features

Various functions are available using a network.
Web & FTP server function, FTP client function, NTP client function



GL840 Main Unit Specifications 

Number of analog input channels 20 channels in standard configuration, Expandable up to 200 channels
Number of analog input terminals Up to 10 terminals (20 channels / terminal), standard config: 1
Type of analog input terminal Multi-input type, Withstand-voltage type
Port for digital sensor 1 port for the sensor/input terminal/adapter of the GL100
External input/
output *1(Input *2)
Trigger or Sampling (1 channel), Logic/Pulse (4 channels)
External input/
output *1 (Output *3)
Alarm (4 channels)
Sampling interval 10 ms to 1 hour (10ms to 50ms: voltage only) *4, External signal
Time scale of waveform display 1 sec. to 24 hour /division
Alarm function (Trigger action)
Start or stop capturing data by the trigger
Alarm function (Repeat action)
Off, On (auto rearmed)
Alarm function (Trigger source)
Start: Off, Measured signal, Alarm, External, Clock, Week or Time
Stop: Off, Measured signal, Alarm, External, Clock, Week or Time
Alarm function (Condition Setting)
Combination: OR or AND
Analog signal: Rising (High), Falling (Low), Window-in, Window-out
Logic signal: Pattern (combination of each input signal in high or low)
Pulse (number of count): Rising (High), Falling (Low), Window-in, Window-out
Alarm function (Alarm output)
Outputs a signal when alarm condition occurs in the input signal *5
Pulse input
function - Rotation count
(RPM) mode
Counts the number of pulses per sampling interval and converts to rpm
(rotations per minute), Number of pulses for one rotation can be set to
50, 500, 5000, 50k, 500k, 5M, 50M, 500M rpm/F.S. (rpm./Full Scale)
Pulse input
function - Accumulating
count mode
Accumulates the number of pulses from the start of measurement
50, 500, 5000, 50k, 500k, 5M, 50M, 500M C/F.S. (Counts/Full Scale)
Pulse input
function - Instant count
Counts the number of pulses per sampling interval
50, 500, 5000, 50k, 500k, 5M, 50M, 500M C/F.S. (Counts/Full Scale)
function - Between channels
Addition, Subtraction, Multiplication, and Division for analog input
function - Statistical
Select two calculations from Average, Peak, Maximum, Minimum, RMS
Search function Search for analog signal levels, values of logic or pulse or alarm point
in captured data
Interface to PC Ethernet (10 BASE-T/100 BASE-TX), USB (Hi-speed), WLAN (using B-568 option)
device - Internal
Built-in 4GB Flash Memory *6
device - External
One SD card slot (Support SDHC memory card, up to 32GB) *7
device - Saved contents
Captured data, Setting conditions, Screen copy
Capturing mode Mode: Normal, Ring, Relay
Ring: Saves most recent data (Number of capturing data: 1000 to 2000000 points) *8
Relay: Saves data to multiple files without losing data until dada capturing is stopped
Replay data Replays captured data that was saved in the GL840 (in GBD or CSV format)
Scaling (Engineering unit) function Measured value can be converted to specified engineering unit
• Analog voltage: Converts using four reference points (gain, offset)
• Temperature: Converts using two reference points (offset)
• Pulse count: Converts using two reference points (gain)
Action during data capture • Displaying past data (using dual display mode (Current + Past data))
• Hot-swapping the SD memory card
• Saving data in between cursors
Display Size 7-inch TFT color LCD (WVGA: 800 x 480 dots)
Display Language English, French, German, Chinese, Korean, Russian, Spanish, Japanese
Display Information *9 Waveform in Y-T with digital values, Waveform only, Digital value, Digital values
and statistics values
Operating environment 0 to 45 ºC, 5 to 85 % RH (non condensed)
(When operating with battery pack 0 to 40 ºC, charging battery 15 to 35 ºC)
Power source - AC adapter 100 to 240 V AC, 50/60 Hz (1 pc of adapter is attached as standard accessory)
Power source - DC power 8.5 to 24 V DC (DC drive cable (option B-514) is required)
Power source - Battery pack Mountable two battery packs (battery pack (option B-569): 7.2V DC, 2900mAh)
Power consumption *10 Max. 38 VA
External dimensions (W x D x H
in mm, Excluding projections)
Approx. 240 x 158 x 52.5
Weight *11 Approx. 1010 g

*1 Input/Output cable for GL (option B-513) is required to connect the signal.
*2 Input signal;

  • Voltage range: Up to 24V (common ground)
  • Signal type: Voltage, Open collector, Contact (relay)
  • Threshold: Approx. + 2.5 V (Hysteresis: Approx. 0.5V (2.5V to 3V))

*3 Output signal: Open collector (pull-up to 5V by 10kΩ resistor) 

  • Voltage: Max. 30V
  • Current: Max. 0.5A
  • Collector dissipation: Max. 0.2W

*4 Minimum interval varies by number of channels used.
*5 Output port can be specified in each input channel.
*6 The built-in Flash memory is available for units with serial numbers C604XXXX or later. Please contact your local representative for more information.
*7 SD memory card cannot be used on the SD card slot while the wireless LAN unit (opton B-568) is used.
*8 Size of the capture data will be limited to 1/3 of available memory.
*9 Display mode is switched every time the dedicated key is pressed. In magnified digital value mode, the
displayed channel number can be specified. In the waveform display mode, the changing of the time scale will
be effective from the point of the next displayed data.

*10 Rating under maximum power consumption using the AC adapter, with LCD display on, and battery pack(s)
being charged.

*11 Excludes AC adapter and battery pack.


Software Specifications for PC

Item Description
Model name GL100_240_840-APS
Supported OS Windows 10, 8.1, 8, 7, Vista (32/64-bit edition)
Supported device GL840 (USB, Ethernet, WLAN), GL100 (USB, WLAN)
Functions Control the GL series, Real-time data capture, Replay data, and Data format conversion
Supported units & channels Up to 1000 channels total, Up to 4 groups (number of units is limited by model)
Settings control Input condition, Capturing condition, Trigger/Alarm condition, Report, etc.
Capturing - data Saved to PC Saves captured data in real time (in GBD binary or CSV format)
Capturing data - Saved to GL unit Saves to the SD memory card (in GBD binary or CSV format)
Displayed information Y-T waveform, Digital values, Report, X-Y graph (specified period of data, data
reply only), Two displays for the current and past data, and Statistical calculation
File operation Converting data format to CSV from GBD binary, merge multiple data files
in the time axis or as an additional channel
Warning function Send e-mail to the specified address when the alarms occur
Statistical calculation Maximum, Minimum, and Avarage during data capturing
Report function Creates the daily or monthly report automatically


Software specifications for Smart device 

Item Description
Model name GL-Connect
Supported OS Android 4.1 to 6.0, iOS 7/8/9 (up to 9.3.4)
Supported device GL840 (WLAN), GL100 (WLAN)
Functions Control the GL series, Display measured data in waveform or digital value
Supported units Up to 10 units
Settings control Start/Stop, Sampling interval
Capturing data Saves captured data in the GL main body (data cannot be saved in the smart device)
Displayed information Data captured in real time by digital value, Replay the data stored in the GL body by the waveform


Wireless LAN Unit (option) Specifications

Item Description
Model number B-568
Supported device GL840
Communication method Wireless communication (using radio waves in the 2.4GHz band)
Supported WLAN system IEEE802.11b/g/n
WPS: Push button or PIN method
Security protocols: WEP64, WEP128, WPA-PSK/WPA2-PSK, AKIP/AES
Communication distance: Approx. 40m (depending on the conditions of radio
Installed location Attaches to the SD card slot *7
Function Access Point mode: Communicate with the GL100-WL as a remote sensor
(captured data in the GL100-WL is transferred to GL840)
Station mode: Communicate with PC or Smart device (control GL840 and
transfer the data from GL840)
Connected number of GL100-WL GL840: Up to 5 units of the GL100-WL


GL840 Analog Input Specifications

Item Description
Input method All channels isolated balanced input *12, Scans channels for sampling
Type of input terminal Screw terminal (M3 screw)
Measurement range (Voltage) 20, 50, 100, 200, 500 mV, 1, 2, 5, 10, 20, 50, 100 V, and 1-5V F.S. (Full Scale)
Measurement range (Thermocouple) Type: K, J, E, T, R, S, B, N, W (WRe5-26)
Range: 100, 500, 2000 ºC *13
Measurement range (RTD - Resistance Temperature Detector) Type: Pt100, Pt1000 (IEC751), JPt100 (JIS)
Range: 100, 500, 2000 ºC *13
Measurement range (Humidity) 0 to 100 % RH - using the humidity sensor (option B-530)
Filter Off, 2, 5, 10, 20, 40 (moving average in selected number)

Measurement Accuracy*14

Voltage ± 0.1% of F.S. (Full Scale)

Temperature (Thermocouple)*15

Type Measurement range
(TS: Temp Sense)
Measurement Accuracy
R 0 ≤ TS ≤ 100 ºC ± 5.2 ºC
100 < TS ≤ 300 ºC ± 3.0 ºC
300 < TS ≤ 1600 ºC ± (0.05% of rdg. + 2.0 ºC)
S 0 ≤ TS ≤ 100 ºC ± 5.2 ºC
100 < TS ≤ 300 ºC ± 3.0 ºC
300 < TS ≤ 1760 ºC ± (0.05% of rdg. + 2.0 ºC)
B 400 ≤ TS ≤ 600 ºC ± 3.5 ºC
600 < TS ≤ 1820 ºC ± (0.05% of rdg. + 2.0 ºC)
K -200 ≤ TS ≤ -100 ºC ± (0.05% of rdg. + 2.0 ºC)
-100 < TS ≤ 1370 ºC ± (0.05% of rdg. + 1.0 ºC)
E -200 ≤ TS ≤ -100 ºC ± (0.05% of rdg. + 2.0 ºC)
-100 < TS ≤ 800 ºC ± (0.05% of rdg. + 1.0 ºC)
T -200 ≤ TS ≤ -100 ºC ± (0.1% of rdg. + 1.5 ºC)
-100 < TS ≤ 400 ºC ± (0.1% of rdg. + 0.5 ºC)
J -200 ≤ TS ≤ -100 ºC ± 2.7 ºC
-100 < TS ≤ 100 ºC ± 1.7 ºC
100 < TS ≤ 1100 ºC ± (0.05% of rdg. + 1.0 ºC)
N -200 ≤ TS < 0 ºC ± (0.1% of rdg. + 2.0 ºC)
0 ≤ TS ≤ 1300 ºC ± (0.1% of rdg. + 1.0 ºC)
W 0 ≤ TS ≤ 2000 ºC ± (0.1% of rdg. + 1.5 ºC)
R.J.C ± 0.5 ºC

Temperature (RTD)*16

Type Measurement range
(TS: Temp Sense)
Pt100 -200 ≤ TS ≤ 100 ºC ± 1.0 ºC
100 < TS ≤ 500 ºC ± 1.0 ºC
500 < TS ≤ 850 ºC ± 1.0 ºC
Pt1000 -200 ≤ TS ≤ 100 ºC ± 0.8 ºC
100 < TS ≤ 500 ºC ± 0.8 ºC
JPt100 -200 ≤ TS ≤ 100 ºC ± 0.8 ºC
100 < TS ≤ 500 ºC ± 0.8 ºC

General GL840 Analog Input Specifications

A/D converter Sigma-Delta type, 16 bits (effective resolution: 1/40000 of the measuring full range)
Input resistance 1MΩ ±5%
Allowable signal source resistance Up to 300Ω
Maximum input voltage - Between (+) / (-) terminal 20 mV to 2 V range: 60 Vp-p, 5 V to 100 V range: 110 Vp-p
Maximum input voltage - Channels ((-) / (-)) 60 Vp-p
Maximum input voltage - Channel / GND 60 Vp-p
Max. voltage (withstand) - Between channels 350 Vp-p (1 minute)
Max. voltage (withstand) - Channel / GND 350 Vp-p (1 minute)

*12 The terminal "b" for using the RTD is connected each other across all channels.
*13 If the specifications of the temperature sensor is lesser or greater than the selected measurement range, GL840
can measure up to the specifications of the sensor.

*14 Subject to the following conditions: 

  • Room temperature is 23 oC ± 5 oC.
  • When 30 minutes or more have elapsed after power has turned on.
  • Filter is set to 10.
  • Sampling rate is set to 1 sec, using 20-channel in GL840-M and 10-channel in GL840-WV.
  • GND terminal is connected to ground.

*15 Wire size of thermocouple used is 0.32mm diameter in the T or K type and 0.65mm diameter in other types.
*16 Supports 3-wire type sensor.


Options and Accessories

Item Model number Description
Input terminal (Multi-inputs) B-564 20ch input terminal, multi-input type
Input terminal (Withstand voltage B-565 20ch input terminal, withstand-high-voltage type
Base unit for input terminal B-566 Base unit for input terminal (B-564 or 566)
Connection cable
for extension terminal
B-567-05 Cable to connect GL840 and B-566, 50 cm long
B-567-20 Cable to connect GL840 and B-566, 2 m long
Wireless LAN unit B-568 WLAN adapter, IEEE802.11 b / g / n
Battery pack B-569 Rechargeable Lithium-ion battery (7.2 V, 2900mAh)
Bracket for DIN rale (GL840 main body) B-570 Bracket for DIN rail (GL840 main body), Build-to-order
Bracket for DIN rail (extension terminal) B-540 Bracket for DIN rail (Input terminal), Build-to-order
Input/Output cable for GL series B-513 2 m long (no clip on end of cable)
DC drive cable B-514 2 m long (no clip on end of cable)
Humidity sensor B-530 With 3 m long signal cable (with power plug)
Shunt resistor B-551-10 250 ohms 0.1% (it converts the signal to the "1-5V" from the "4-20mA")
AC power adapter ACADP-20 Input: 100 to 240 V AC, Output: 24 V DC
Temp & Humidity sensor GS-TH Temperature and humidity measurement
Illuminance & UV sensor GS-LXUV Illuminance and UV intensity measurement, cable 20cm long
Carbon Dioxide (CO2) sensor GS-CO2 CO2 measurement, cable 20cm long
Acceleration & Temp sensor GS-3AT Acceleration and temperature measurement, cable 20cm long
Thermistor input terminal GS-4TSR Temp measurement (using a Thermistor), cable 20cm long
Thermistor sensor (Normal type) GS-103AT-4P Temperature sensor (-40 to 105 ºC), 3m long, 4pcs/set
Thermistor sensor (Ultrathin type) GS-103JT-4P Temperature sensor (-40 to 120 ºC), 3m long, 4pcs/set
AC current sensor adapter GS-DPA-AC Current measurement (using a CT), cable 20cm long
AC current sensor (50A) GS-AC50A Current sensor (CT) 50A, cable 20cm long
AC current sensor (100A) GS-AC100A Current sensor (CT) 100A, cable 20cm long
AC current sensor (200A) GS-AC200A Current sensor (CT) 200A, cable 20cm long
Voltage & Temp input terminal GS-4VT Voltage or Temperature (using a thermocouple), cable 20cm long
Module extension cable GS-EXC Extension cable for the sensor / terminal / adapter module, 1.5m long
Dual port adapter GS-DPA Connect up to 2 sensor modules

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