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Multiloggers Transmitters
And Regulators
Recorder with Printer

Web Sensor P8541 - four channels remote thermometer hygrometer

code: P8541
Four channel p-line Web Sensor. Temperature and humidity + temperature probes are supported. Remote alarm.

WiFi Router Easy wireless communication using Web Sensor and optional  Wireless TP-LINK router.


Included in delivery:

Supported optional probes:


Send request



  • Server rooms monitoring
    Temperature/humidity monitoring of the server rooms and rack units, SNMP monitoring, remote alarm by email and Syslog

  • Building HVAC management
    Temperature/humidity monitoring of buildings, history data to Comet Database, remote alarm by email

  • Warehouses
    Temperature/humidity monitoring of storage, history data to Comet Database or 3rd party SCADA system

  • Museums, archives, galleries
    Temperature/humidity is requested for rooms where old valuable documents are stored, history data to Comet Database, remote alarm by email

  • Factories and manufacturing
    Temperature/humidity monitoring for food processing industry, pharmaceutical industry, aerospace industry, etc.

  • Home automation
    Residential room monitoring, remote alarm by email

  • Air-conditioned rooms
    Temperature rising indicates cooling fault, remote alarm by email
  Temperature Humidity 4-channels Ethernet WWW WWW config 1000 values Graph CSV events Email Modbus XML SNMP Trap SOAP Syslog SNTP MIN/MAX

P8541 demo


  • Comet Database
    Complex solution for data acquisition and analysing. Easy to use and high flexible Database software for Comet Web Sensors and Regulators.

  • T-Sensor software
    Free configuration utility for Comet Transmitters and Regulators.

  • SensorReader software
    Basic data acquisition utility for Comet Transmitters and Regulators. Software is free for download.

  • 3rd party software
    Cacti, InTouch, ControlWeb, EasyView, LabVIEW. Support for this software is provided by the 3rd party companies.
  Online Ethernet Monitoring system


Probes - temperature and humidity
Temperature Humidity 4-channels Web Sensor is designed to measuring from digital temperature or humidity+temperature probes. Four channel device for maximum flexibility and efficiency of network resources usage (e.g. IP address). Maximum four digital cable probes can be connected. E.g. 4xT or 4xRH or 2x(T+RH).
Temperature and temperature+humidity probes are available as optional accessories. Temperature can be displayed in degree of Celsius or degree of Fahrenheit. Relative humidity is measured at percent of RH.
Ethernet interface
Ethernet 10Base-T/100Base-TX Ethernet interface via standard RJ45 connector. IP address can be obtain automatically from DHCP server or set manually. Internet protocol version 4 is supported only.
WWW server
WWW WWW config Actual measured values are accessible via powerful embedded web server. Web pages are ready for access from mobile devices like smartphones and tablets. Device configuration via web pages is possible too. Web Sensor allows to user customize the design of web pages.
History values memory
1000 values Measured values are stored into history memory according selected time interval. Capacity of the memory is 1000 records for each channel. Values inside history memory are not backuped. Memory is cleared after device restart.
History graphs
Graph Graphs with history values are accessible via web pages. Modern HTML5 canvas graphic component allows to use graphs from thousands of devices. It is not problem show graphs on tablets or smartphones. All modern web browsers are supported - Firefox, Opera, Chrome or Internet Explorer 9.
History export to CSV
CSV History values can be exported for next processing by the CSV file. CSV file can be processed inside spreadsheet application like Microsoft Excel or OpenOffice Calc. Two formats of CSV file are supported - dot and comma decimal point separators. Timestamps inside CSV file are shown when device time is synchronised by the SNTP server. CSV file can be downloaded from web pages or periodically send as email attachment.
Email Alarm events from temperature and humidity channels are stored into eventlog. This log can be viewed on webpages or stored into CSV file. Capacity of this log file is 100 events. Values inside eventlog are not backuped. Log is cleared after device restart.
Email Warning email are sent when measured value exceed selected limits. Emails are also send when values returns back into safe range. SMTP authentication is supported, but SSL not. Domain name for SMTP server address is supported. Emails with CSV file attachment can be sent at selected intervals.
ModbusTCP protocol
Modbus Modbus protocol for communication with SCADA systems or third party software. Device use Modbus TCP protocol version. Two Modbus clients can be connected to device at one moment.
Actual values via XML
XML XML protocol for actual measured values reading. This protocol is suitable for Web Sensor integration into 3rd party SCADA systems.
SNMP protocol
SNMP SNMP version 1 protocol for IT infrastructure. Using SNMP protocol you can read actual measured values, alarm status and alarm parameters. Via SNMP protocol is also possible to get last 1000 measured values from history table. MIB tables with OID description are available.
Trap SNMP Trap for IT infrastructure. Web Sensor allows sending Traps to selected Trap receiver server. Traps are sent in case of alarm on channel or at error states like unable to send email, unable to deliver SOAP message, etc.
SOAP protocol
SOAP Web Sensor allows to send currently measured values via SOAP v1.1 protocol. The device sends values in XML format to the web server. The advantage of this protocol is that communication is initialized by the device side. Due to it is not necessary use port forwarding.
Syslog protocol
Syslog Syslog protocol for IT infrastructure monitoring systems. Web Sensor allows sending text message to selected Syslog server. Messages are sent in case of alarm on channel or at error states like unable to send email, unable to deliver SOAP message, etc.
SNTP protocol - time synchronization
SNTP Time synchronisation with SNTP server. Actual time is shown at web pages and is necessary for timestamps inside CSV files. Synchronisation interval can be set to one day or to one hour.
MIN/MAX memory
MIN/MAX Memory for minimum and maximum values. Memory is independent on values in history memory. Minimum and maximum values can be cleared according user requirements.

Technical Data

Technical parameters Value
Output Ethernet
Measured Value Temperature + Relative Humidity
Construction Type For External Probes
Design Industrial
Temperature Measuring Range -55 to 100 °C
Relay Output No
Two-State Input No
Lcd Display No
PoE No
Accuracy with DSTR162/C, DSTGL40/C, DSTG8/C probe ±0.5°C from -10 to +80°C, else ±2°C
Accuracy with DSRH01, DSRH02, DSRH05 probe ±3.5% RH (10% – 90% RH) at 25°C, ±2°C
Measuring temperature range with DSTR162/C, DSTGL40/C probe -30 to +80°C
Measuring temperature range with DSTG8/C probe -50 to +100°C
Measuring relative humidity range with DSRH01, DSRH02, DSRH05 probe 0 to 100%RH (not condensing)
Measuring temperature range with DSRH01, DSRH02, DSRH05 probe 0 to +50°C
Resolution 0.1°C, 0.1%RH
Measuring interval 2s
Supported units degrees Celsius, degrees Fahrenheit, percent of Relative humidity
Temperature operating range -30 to +80°C
IP protection IP30
LAN connection RJ-45 connector, 10Base-T or 100Base-TX
Communication protocols WWW, ModbusTCP, SNMPv1, SOAP, XML
Protocols for alarms E-mail, SNMP Trap, Syslog
Configuration T-Sensor, WWW configuration
Power 5Vdc, maximum consumption 1W
Power connector co-axial, diameter 5.5 x 2.1 mm
Dimensions 88 x 74 x 39.5 mm (W x H x D)
Weight approximately 135g
Warranty 3 years
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