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Squirrel 450/850 Series Data Logger

Squirrel 450/850 Series Data Logger

Quick Overview

The Squirrel 450/850 series is a cost effective portable data logger with a maximum of 4 or 8 universal inputs. In common with its bigger brother, the Squirrel 1000 series data logger, the 450 and 850 series are equipped with impressive specifications, long battery life and a three year guarantee. Models 451 and 851 have 4 or 8 universal inputs respectively, configurable for voltage, current and temperature for both thermocouple and thermistor sensors. In addition a serial interface is available for special applications, eg. Vaisala weather sensors WMT52 & WXT520.
View Options



The current 450/850 series consists of the following models, each offers a wide variety of user applications:

Model Inputs Features
4 channels
8 channels
Each channel configurable for temperature, voltage or current input
4 channels
8 channels
0.1sec Interval (Fast Recording feature)
451pH 4 channels Supports up to 2 x external pH adaptor module type pH-int (purchased separately).
451MC 4 channels PCMCIA memory slot installed to accept SRAM card (purchase separately)
452 4 Pulse only channels See CPU module
453 1 Event + 8 Pulse inputs (5Hz) for slow counting  
4 channels
8 channels
plus 1 x Pulse and 1 x Event Input
4 channels + 1 Serial
8 channels + 1 Serial
Serial input configured for Vaisala WXT520/WMT52 Weather Sensors
4 channels
8 channels
Includes +/-10mV range,. for use with Hukseflux HFP01 Heat Flux Sensor.

Factory installed Options

Pulse input
The 451/851 only is available with:

  • Two pulse inputs

pH adaptor module type (pH IFU )

  • For use only with the 451MC

PCMCIA Card Slot

As an option, the data logger can be fitted with a slot for an SRAM memory card. The data logger can record directly onto the card or the user can copy the internal memory to the card for easy transfer of the data to a computer equipped with a PC card slot. SRAM cards are available for storing up to 2M readings. Darca Software includes tools for setting up the card and transferring the data from the card to a file suitable for analysis or translation to ASCII format using any of the standard software.

We recommend using King Max, Panasonic or Mitsubishi cards as these have the lowest power consumption. Note: we have found that not all SRAM cards are suitable, particularly those with rechargeable batteries and that some older versions have unacceptably high power consumption when used with Squirrel - especially when battery powered. Refer to Accessories for the SRAM details.

Field installed options

The memory can be expanded to 2M readings (about 2,080,000). Refer to the Options section for details.

Don't forget that a lot of memory takes time to download and that it is possible to reduce the amount of memory used for a logging run. Eltek loggers now download at 38400 baud, and in practice this is about 500 readings per second.

Common Features

All models feature panel mounted controls (except the 401) and a 2 line, 32 character LCD readout for setting up, monitoring and reading recorded events on the logger. Resolution is 12 bit with standard thermistor, thermocouple and DC voltage or current inputs. Two sensor power outputs are available to power external sensors - such as humidity probes.

EU Range
In addition "EU" range is standard, enabling the logger to independently rescale each input to a user defined engineering unit, e.g. humidity can be displayed as 0 to 100% RH, permitting quick and unambiguous understanding of the readings on the display.

Internal memory
The logger is fitted as standard with 250K of memory, backed up by a lithium battery, and at least 250,000 locations are available for data storage. Note that this refers to data storage, not bytes, as 2 bytes of conventional memory are used for every reading. Larger memory can be field fitted by a competent engineer as an option.


The Squirrel 450/850 series shares many of the accessories available to the Squirrel 1000 series datalogger. The most significant exceptions are noted.


The 450/850 series is fully compatible with the Eltek Darca Lite and Darca Plus software, providing comprehensive remote control, data transfer and analysis tools using a Windows based PC.

Connection to the PC can be:

  • Direct - use the LC68 computer cable.
  • Remote - via a landline - use a commercially available modem (use only Darca Plus software).
  • Remote - via a cellular network - use the GSM modem kit type GSM-mdm c/w antenna.
  • Remote - via Ethernet - for networked Squirrel dataloggers use the Moxa De311 serial to ethernet convertor.
  • Specification

    Accuracy (at 20ºC) Analogue Inputs: ±0.1% of reading
    ±0.2% of full range span
    Environment Ambient temperature: -30ºC to 65ºC
    Humidity up to 95% (non condensing)
    Power Supplies Internal: 6 x AA Alkaline batteries (9V nominal)
    External: 9-14V DC (1.4 Watts)
    Battery Life At least 6 months with all 8 channels recording every 5 minutes
    Clock Accuracy 1 second/day at 20ºC
    Physical details Dimensions (mm): H 120, W 180, D 62
    Weight, inc batteries: Approximately 1Kg
    Material: ABS coated with durable NEXTEL finish
    Interface RS232 half duplex - 2400 to 38,400 Baud
    Connectors RS232 Output:
    6 pin female mini-DIN
    3 pin ST Plug (5mm pitch "screw Terminal")
    Input impedance Voltage and Thermocouple: 1M Ohms
    Current: 10 Ohms
    Sensor power outputs Internally selectable to 5V regulated or Squirrel supply voltage.


    Input typeAvailable rangesResolution
    Thermistor -50 to 150ºC 0.1C
    Thermocouple - Type K 0 to 900ºC 0.5C
    Thermocouple - Type K -200 to 450ºC 0.2C
    Thermocouple - Type T -200 to 350ºC 0.2C
    Voltage 0 to 50mV 50µV
    0 to 100mV 50µV
    0 to 200mV 50µV
    0 to 500mV 0.5mV
    0 to 1V 0.5mV
    0 to 2V 0.5mV
    0 to 5V 5mV
    0 to 10V 5mV
    0 to 20V 5mV
    -25 to 25mV 50µV
    -50 to 50mV 50µV
    -100 to100mV 50µV
    -250 to 250mV 0.5mV
    -500 to 500mV 0.5mV
    -1 to 1V 0.5mV
    -2.5 to 2.5V 5mV
    -5 to 5V 5mV
    -10 to 10V 5mV
    Current 4 to 20mA 0.05%
    0 to 20mA 5µA

    Availability: Stock Item


    Components / Downloads

    For further information, technical advice, or a quotation please call or email us. If you are not sure which product you need one of our technical sales advisors will be happy to discuss your application. We also accept company purchase orders by fax or post. Credit card orders can also be placed over the phone for any product.

    Data Loggers
    8 Channels. Universal inputs each V/C, thermistor or thermocouple ( max 1Hz)
    View FileDatasheet
       Size: (419.62 KB)

    Not Available online

    4 Channels. Universal inputs each V/C, thermistor or thermocouple ( max 1Hz)

    Not Available online

    DARCA Plus Version 3.0. Downloading And Remote Control Application for GEN II Receiver Loggers and Squirrel 1000 Series data loggers. Powerful graphing tools display real-time or historical data, summary window displays data and statistical information, configures GEN II transmitters and map transmitter to Squirrel channels, password protected, printer output, connection to loggers via serial port, USB, GSM or land line.
    View FileDatasheet
       Size: (1.92 MB)
    or call us for a quote