Squirrel 450/850 Series Data Logger

451 / 452 Squirrel Data Logger

The Squirrel 450/850 series is a cost effective portable data logger with a maximum of 4 or 8 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. The model 451 and 451 T are universal instruments with configurable inputs for voltage, current and temperature for both thermocouple and thermistor sensors. The model 851 is the 8 input version of the 451.

The 450/850 Series Range Of Models

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

Model	Inputs	Features
451 851	4 channels 8 channels	Each channel configurable for temperature, voltage or current input
451T	4 channels	0.1sec Interval (Fast Recording feature)
451pH	4 channels	Supports up to 2 x external pH adaptor module type pH IFU(purchased separately).
451MC	4 channels	PCMCIA memory slot installed to accept SRAM card (purchase separately)
452	4 Pulse only channels	See CPU module
453	8 Event + 8 Pulse inputs (5Hz) for slow counting
454	8 Event	Uses standard rising cage connectors for easy connection.
401	4 channels	'Blind' 451 - less display and control panel

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.

Accessories

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

Software

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:

Specification

Accuracy (at 20ºC)	Voltage/Current: Temperature:	±0.1% of reading ±0.1% of span ±0.1% of reading ±0.1% of span
Environment	Ambient temperature:	-30ºC to 65ºC Humidity up to 95% (non condensing)
Power Supplies	Internal:	Six AA manganese alkaline batteries (9V nominal)
	External:	9-14V DC at 100mA.
Battery Life	At least 6 months with all 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	RS232C at up to 38,400 Baud
Connectors	RS232 Output: Inputs:	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.

Ranges