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Multiloggers Transmitters
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H7531R temperature, humidity and barometric pressure rack mount monitor

code: H7531R
Humidity, temperature, atmospheric pressure monitor with two relay outputs.

Relative humidity, temperature probe on a cable. Measured values are also converted to other humidity interpretation: dew point temperature, absolute humidity, specific humidity, mixing ratio, specific enthalpy. Built-in pressure sensor. Three two-state inputs.


Included in delivery: 

  • Traceable calibration certificate
  • Quick start manual
  • Free program TSensor for configuring of the transmitter is ready to Download
  • Free program SensorReader for logging values from one transmitter via Ethernet to a PC disk file is ready to Download

Send request


Server monitoring system is designed for 19-inch rack mounting, the height is one rack unit - 1U. Rack-mount monitors are very convenient for cabinets.
The Hx531R monitor can be fitted into a rack "zero U" because of its thin design.
It can fit behind other equipment taking up space that is otherwise unusable.
Model H4531R is prepared for connection of external Pt1000 temperature probe and models H3531R, H7534R are equipped with 1 meter temperature + humidity probe. Unit also contains three binary inputs for detection of two-state events - e.g. power presence, water, smoke, airflow, glass break detection, door contact.
Rack unit provides 5Vdc and 12dc power supply for external all sensors and detectors.
Large dual line LCD for simultaneous display of temperature, humidity is an advantage. Parameters are easy adjustable from transmitter keyboard or from the computer.
State-of-the-art capacitive polymer sensor ensures excellent calibration long term stability, inertia against water and condensation.
Environmental monitor is equipped with two relay outputs for alarm indication or control of external devices. Each relay can be assigned to any measured value. 


APPLICATIONS - online monitoring of temperature, humidity, power, flood, smoke, airflow, room entry at:

  • server and computer rooms
  • rack monitoring
  • industrial Ethernet
  • telecommunication devices
  • building management and automation

Easy creation of online data acquisition system from Ethernet sensors by using new low cost database software Comet

DBS Sensor Monitor

Rack monitoring system


- see also Optional Accessories.


Modbus TCP: Modbus TCP protocol enables to read measured values, set alarm limits, adjust the probe.
Telnet: Port 9999 enables to set alarm limits (lower, upper limits, hysteresis for measured values and time delay), e-mail addresses, SNMP addresses, probe description, refresh of www pages (10s to 65535s), set storing interval to history (10s to 65535s), enable each communication channel. Capacity of the history memory is 100 sets of temperature, humidity, pressure + computed values. Password protection of this port is enabled. Automatic IP address assignment from DHCP server is also enabled.
WWW pages: User selectable design of www pages enabling to display curve of measurement history. User can design the look of www pages and temperature, humidity, pressure + computed values history.
SNMP: It is possible to read actual values and alarm limits. In case of alarm creation warning message (trap) is sent to addresses defined by the user (maximum three addresses).
SOAP: Online transmitter enables to send actual measured data in the format of SOAP message to selected web server in preset interval 10-65535 s.

Online transmitter enables to monitor measured values. In case of exceeding of adjusted limits warning message can be sent to specified addresses. 

There are the following options of alarm indication:

E-mail: In case of alarm creation warning e-mail message is sent to addresses defined by the user (maximum three addresses) or via e-mail to SMS message. Basic SMTP autentization is supported.
SNMP: In case of exceeding of adjusted temperature, humidity, pressure + computed value limits alarm is activated and warning trap is sent to user specified IP addresses (maximum 3 addresses).
WWW pages: In case of exceeding of adjusted temperature, humidity, pressure + computed value limits active alarm is displayed on www page.
syslog: Online transmitter enables to send text messages to selected syslog server after different events appear. E.g. after transmitter restart, alarm activation, communication error with SNTP, after firmware change, after alarm termination, after communication error with SOAP server.

Synchronizing of time and record to www table and measured values history is enabled by SNTP via Internet.


For acquiring values from several transmitters, also third party software is possible to use. Tested functionality is with programs:

LabVIEW from National Instruments, by means of the free Modbus Library for LabVIEW.

TIRS.NET - transmitters are also directly supported by program TIRS.NET from Coral s.r.o. company. Please download demo enabling full work with transmitters.

Tested functionality is also with program ControlWeb


Figure: Relative humidity operating range

Technical Data

Technical parameters Value
Output Ethernet
Measured Value Temperature + Relative Humidity + Atmospheric Pressure
Construction Type With T+RH Probe on Cable
Design Rack 19"
Temperature Measuring Range -30 to 105 °C
Relay Output Yes
Two-State Input Yes
Lcd Display Yes
PoE No
Relative humidity range 0 to 100%
Accuracy of relative humidity measurement ±2.5% relative humidity from 5 to 95% at 23°C
Accuracy of temperature output ±0.4°C
Maximum measuring pressure range 600 to 1100hPa
Accuracy ±1.3hPa at 23°C
Resolution 0.1°C, 0.1%RH, 0.1hPa
Measuring interval 2s
Available temperature units degrees Celsius, degrees Fahrenheit
Computed values dew point, absolute humidity, specific humidity, mixing ratio, specific enthalpy
Available pressure units hPa, kPa, mbar, mmHg, inHg, inH2O, PSI, oz/in2
Accuracy and range of dew point temperature output - for more details see graphs in manual ±1.5°C at ambient temperature T<25°C and RH>30%
range -60 to +80°C
Accuracy and range of absolute humidity output ±1.5g/m3 at ambient temperature T < 25°C
range 0 to 400g/m3
Accuracy and range of specific humidity output ±2g/kg at ambient temperature T < 35°C
range 0 to 550g/kg
Accuracy and range of mixing ratio output ±2g/kg at ambient temperature T < 35°C
range 0 to 995g/kg
Accuracy and range of specific enthalpy output ±3kJ/kg at ambient temperature T < 25°C
range: 0 to 995kJ/kg
Temperature compensation of the humidity sensor all temperature range
Temperature operating range -30 to +80°C
IP protection IP40
Number of relay outputs 2
Maximum switching voltage, current and power of relay output 50V, 2A, 60VA
Number of binary inputs 3
Signal for binary inputs dry contact, open collector or two-state voltage signal.
Inputs are not galvanically isolated.
Minimum pulse length at binary input 500ms
Low voltage level 0 to +0.5 V
High voltage level +3.0 to +30V
Audible alarm built-in beeper - switchable
LAN connection RJ-45 connector, 10Base-T or 100Base-TX
Communication protocols WWW, ModbusTCP, SNMPv1, SOAP
Alarm protocols E-mail (SMTP authentication is supported), SNMP Trap, Syslog
Configuration T-Sensor, Telnet, keyboard
Temperature operating range of LCD display readable to operating temperature +70°C, it is recommended to switch OFF the LCD over +70°C
Filtering ability of sensor cover 0.025mm - filter with stainless steel mesh
Power 12Vdc, maximum consumption 1W
Power connector co-axial, diameter 5.5 x 2.1mm
Length of the probe cable 1m, 2m or 4m optionally
Dimensions 483 x 44 x 45mm (W x H x D), one 19" rack unit 1U
Weight approximately 1090g - 1m probe
Warranty 3 years
Database Viewer for Comet Database Database Viewer for Comet Database
code: DBV
Low cost browser Database Viewer enables several clients to view database from different places on network/internet.
H7530 - thermometer hygrometer barometer with Ethernet interface and relays H7530 - thermometer hygrometer barometer with Ethernet interface and relays
code: H7530
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MS6-Rack data logger MS6-Rack data logger
code: MS6-Rack
The complete solution for monitoring of temperature, humidity and other values. For mounting to 19" rack - one rack unit 1U. Enables to build in the optional MP016 output relays module with 16 relays - see Optional accessories.