Powering the dataTaker
The dataTaker can be powered from a variety of power sources. These sources are categorised as external power supplies and internal or backup power supplies.
External power supplies include
the AC mains/line voltage via the 12 volt power adaptor supplied with the logger
various 12 to 18 Volt external batteries that can be connected to the dataTaker as external power supplies
Internal power supplies include
a rechargeable 6 Volt lead acid battery which is connected as the 'internal' or backup battery. This battery is mounted externally for the dataTaker 50, and can be mounted internally or externally for the dataTaker 500/600 series loggers. The battery is automatically re-charged whenever external power is supplied.
a 9 Volt alkaline D cell battery pack
The basic power requirements of the dataTaker depends on the operating conditions, but is approximately 120 mA for normal operation, and approximately 600 mA when recharging the battery, at 12 Volts AC or DC power supply.
If power is drawn from the excite terminals of the analog input channels, or if power is drawn from the 5 Volt sensor power supply terminal, then the total current drawn will be higher during periods of scanning activity.
The dataTaker has two power modes - normal power mode and low power mode. These modes are automatically selected depending on activity.
There is no general power supply or battery ON/OFF switch on the dataTaker.
Low Power Mode
The dataTaker is designed to operate as a low power data logger, conserving power during periods of no activity by entering a low power mode. Only the real time clock, memory, wake detect circuit and high speed counters remain powered in the low power mode.
The low power mode allows the internal batteries to be used as the sole power supply for long periods, depending on operating conditions and scanning activity.
The dataTaker draws approximately 120 mA when operating in the normal power mode, while scanning input channels, monitoring alarms, and communicating with the host.
However whenever there is no scanning required, and there is no communications, then the dataTaker automatically drops to the low power or 'sleep' mode when it draws less than 400 µA.
The dataTaker 'wakes' up to the normal power mode in response to a number of conditions as follows
a scan of the input channels becomes due, including for alarms and statistics
communications is received by the serial interface
a memory card is inserted or removed
a change of state (edge) is received on the Wake terminal
a key is depressed on the Display/Keypad (where fitted)
the dataTaker also wakes every 18 minutes for time keeping
Note : Pulses or changes of state on the digital input channels or the high speed counter channels do not wake the dataTaker.
Selecting the Power Mode
The automatic low power mode of operation is enabled or disabled by the Parameter15 command (See Section III ñ Parameter Commands) as follows
Parameter15=0 Automatic low power selection (Default)
Parameter15=1 Force low power mode
Parameter15=2 Disable low power mode
The command for example
will force the dataTaker into the low power mode immediately. The current setting for the power mode can be determined by the command
Selecting Automatic Low Power Mode
The dataTaker defaults to automatic low power selection (Parameter15=0) whenever it is initially powered up or executes a RESET command.
Automatic low power selection only operates when the dataTaker is powered from the internal or backup battery. If the dataTaker is powered from an external power supply, then the logger remains in the normal power mode.
When awake, the dataTaker measures the internal battery current every second to determine the method of powering. If automatic low power mode is selected, then
if the battery current is negative (battery is providing power) then the low power mode is selected, and the logger sleeps during periods of inactivity
if the battery current is positive (battery is recharging from external power) then the low power mode is not selected, and the logger does not sleep during periods of inactivity
Force Low Power Mode
When the dataTaker is externally powered, the logger does not normally drop to the low power mode during periods of inactivity (see above).
However the low power mode can be forced when the dataTaker is externally powered, by the Parameter15 command as follows
This allows power consumption from an external power supply to be reduced whenever the logger is inactive. This is particularly relevant if the power supply is a 12 Volt wet cell battery connected to the AC/DC power supply input.
Disable Low Power Mode
Whenever the dataTaker is powered from the internal or backup battery, it automatically selects the low power mode during periods of inactivity (see above).
Automatic low power mode selection can be disabled if necessary when the dataTaker is powered from the internal battery, by the Parameter15 command as follows
which will force the logger to remain in the normal power mode.
Low Power Delay
When automatic low power selection is enabled, and the dataTaker has powered down to the low power mode, then the logger powers up or 'wakes' to the normal power mode in response to a number of conditions as follows
when a new scan of the input channels becomes due. The scan is performed and the logger then drops to the low power mode again.
when any communications are received from a host computer. The logger remains powered up for a period after the last character is received, and then drops to the low power mode again.
when a memory card is inserted or removed. The logger remains powered up for a period, and then drops to the low power mode again.
when the Wake terminal is connected to a GND terminal. The logger remains powered up for a period, and then drops to the low power mode again.
The delay before automatic power down following communication, memory card insertion or removal, or wake terminal activity is 30 seconds by default. This delay period can be defined from 1 to 255 seconds by the Parameter17 command (See Section III ñ Parameter Commands).
The command for example
defines the delay before automatic power down to be 1 minute. The current setting for the delay before automatic power down can be determined by the command
The dataTaker will not power down in the automatic low power mode unless it can sleep for at least one full second.
Controlling Waking of the dataTaker
The dataTaker will normally wake when time triggered Schedules are triggered for scanning. Schedules can be disabled from waking the logger by the Parameter20 command, which defines a bit mask of Schedules not to wake the logger as follows
Figure 6 - Bit Map for Schedules to Wake dataTaker
The default is Parameter20=0, which means that all Schedules can wake the logger when they become due.
Parameter20 is set to the decimal value of the bit mask defining which Schedules are not to wake the logger. The decimal value for each Schedule in the mask is indicated in the diagram above.
The command for example
will disable the Alarm Schedule (1) and Triggered Schedule D (64) from waking the logger.
The Parameter20 command does not disable scanning of Schedules if the dataTaker is already awake.
The dataTaker will not wake for event based scanning, and so steps must be taken to ensure that external pulses wake the logger via the Wake terminal (see below).
The Wake Terminal
Waking of the dataTaker from low power mode can also be controlled by the Wake terminal. A low state of less than 1.0 Volts on the Wake terminal will wake the logger in less than 300 mS.
The wake signal can be generated by relay closures, an open collector NPN transistor switching to ground, etc. The wake terminal has an internal 1800 Ohm pull up resistor to 5 Volts. A permanent low state on the wake terminal will not prevent short periods (100 mS) of sleep if there is no Schedule activity. Only setting Parameter15=2 will keep the logger permanently awake.
The External Power Supply
The dataTaker can be powered from any external power supply which has the following specifications
9 to 15Volts AC, at 600 mA
10 to 17 Volt DC, at 600 mA
dataTaker 500/600 series loggers
9 to 18 Volts AC, at 600 mA
11 to 28 Volt DC, at 600 mA
The dataTaker is supplied with a 12 Volt power adaptor, which can be used to power the logger from the local mains/line power supply.
However other external power sources can be used to power the dataTaker, including external 12 Volt dry cell or wet cell batteries, solar panels, vehicle power supplies, etc.
The dataTaker draws approximately 120 mA in the normal power mode to power the logger. Whenever the backup lead acid battery is being recharged, then an additional charging current of up to 300 mA is drawn if the battery is fully discharged. Therefore the external power supply must be able to supply up to 450mA if a rechargeable lead acid battery is fitted, or 150 mA if a battery is not fitted.
The external power supply is connected to the dataTaker 50 via the removable screw terminals labelled Power AC/DC (See Figure 7), located near to the Converting LED.
The external power supply is connected to the dataTaker 500/600 series loggers via the screw terminals labelled AC/DC (See Figure 7), located near the 9 pin D connector of the RS232 COMMS serial interface.
The external AC/DC power input is bridge rectified before being applied to the battery charger and regulator circuits. Therefore if a floating external power supply is used, the polarity of the external power supply connection is not important.
Note: If an external DC power supply is to be grounded to dataTaker ground, then negative ground is mandatory. A positive ground will damage the bridge rectifier.
In this case the positive side of the external power supply must be connected to either of the AD/DC screw terminals, and the negative side connected to a GND terminal.
The Internal or Backup Battery
The dataTaker internal or backup battery provides primary power in the absence of an external power supply, and acts as a backup when the external power supply is changed or fails. The battery can power the dataTaker for long periods, depending on the scanning activity and the frequency of communications.
The battery for the dataTaker 50 is always mounted outside of the body of the logger. The battery for the dataTaker 500/600 series data loggers is either mounted within the body of the logger, or outside of the body of the logger. The internal battery can be either a 6 Volt sealed lead acid gel cell, or a 9 Volt alkaline D cell battery pack.
A lead acid internal battery is recharged whenever the logger is powered from external power. Full recharge takes 8 hours for the 1.2 Ah lead acid battery, and longer for the larger capacity batteries. The battery charger circuit of the dataTaker is designed for long term battery maintenance.
The dataTaker 500/600 series loggers are shipped with the internal lead acid battery installed but not connected. The battery must be connected at first use of the logger, in accordance with the tag attached to the battery cable.
When the dataTaker is not in use, then the lead acid battery should be disconnected or the logger be left on charge. Failure to do this will allow the logger to is fully discharge the battery, which will eventually shorten the effective battery life.
Lead Acid Backup Battery dataTaker 50
The backup battery for the dataTaker 50 is not installed in the chassis of the logger. The battery is always located outside of the logger, and connects to the battery screw terminals. A backup battery is not supplied with the dataTaker 50.
The backup battery can be any 6 Volt lead acid gel cell battery, for which a number of capacities are available including 1.2 AHr, 4 AHr and 10 AHr. The battery is connected to the screw terminals labelled Lead Acid + and Lead Acid ñ.
Lead Acid Backup Battery dataTaker 500/600 Series
The dataTaker 500/600 series loggers is supplied with a 6 Volt 1.2 Ah lead acid gel cell battery. This battery is located under the top cover of the logger.
A larger capacity 6 Volt lead acid battery can be externally connected to the dataTaker 500/600 series loggers, to provide greater backup capacity and hence longer periods of operation under battery power. This larger battery is located outside the chassis of the dataTaker 500/600 series loggers, but generally within the enclosure which houses the logger. This external battery is connected to the two screw terminals labelled Batt + and Batt ñ . These terminals are illustrated in Figure 7 below.
An external battery is connected to the Batt + and Batt ñ terminals is recharged whenever the logger is externally powered.
Alkaline Backup Battery
The backup battery for the dataTaker data loggers can also be a 9 Volt alkaline D cell battery pack. These typically have 17-20 Ahr capacity, and so can provide longer term operation of the logger when it is powered solely from the battery.
Standard alkaline batteries are not rechargeable, and so there are separate battery terminals for lead acid and alkaline batteries. There is no charging current output on the alkaline battery terminals whenever the logger is powered from external sources
The 9 Volt Alkaline battery is connected to the dataTaker 50 via the battery screw terminals on the top of the logger, labelled Alkaline + and Alkaline ñ (see Figure 2).
The 9 Volt Alkaline battery is connected to the dataTaker 500/600 series loggers via a three pin internal battery connector on the upper printed circuit board of the logger (See Figure 4). The internal battery connector is accessed by removing the battery cover. The connector is polarized. and care must be taken when installing the alkaline battery that the battery connects to the Alkaline + and Negative pins.
Figure 7 ñ dataTaker Power Supply Connections
Caution : The 9 Volt Alkaline battery must not be connected to dataTaker 500/600 series loggers via the external Bat + and Bat ñ screw terminals if an external power supply is also used. A charging current is output from these terminals whenever these loggers are externally powered, that will destroy the alkaline battery.
The alkaline batteries are available from your dataTaker supplier.
The dataTaker battery will power the logger for varying periods, depending on the battery type and operating conditions.
A general guide to battery life for the 1.2 AHr and 4 AHr lead acid gel cell and the alkaline battery pack is presented in the following table for different sampling intervals. The table assume that automatic selection of low power mode is enabled, and that the dataTaker is allowed to drop to the low power or sleep mode between scans.
Battery life is substantially reduced if the dataTaker is used to continuously monitor alarm inputs, continuously scan for statistical data, power sensors or excite sensors.
Using the Battery Life Chart
The Battery Life Chart illustrated in Figure 8 below can be used to estimate battery life.
Figure 8 - dataTaker Battery Life Chart
Battery life is estimated for different operating conditions as follows
Establish the scan interval, and find it on the Scan Interval axis. The chart shows an example of 30 seconds.
Project a vertical line to the curves. These curves correspond to the different numbers of channels. Interpolate if necessary. Channels are assumed to be analog, however for this estimation a digital channel is equivalent to one quarter of an analog channel. The chart shows an example of 10 channels.
From the curve intersect project a horizontal line to the right across three scales, which correspond to standard dataTaker battery sizes, where the battery life can be read. The example in the chart shows that the battery life would be 300, 800 and 4000 hours for the 1.2, 4 and 17 Ahr batteries respectively.
If a non-standard battery is employed, then the chart axis on the left is used and the battery life is equal to the scale value multiplied by the battery's amp-hour rating (220 hours for the example).
A Few Details
The dataTaker takes approximately 300mS to wake up, 40mS to sample each analog channel, 10mS to sample each digital channel and 10 to 50mS for each calculation.
Also the dataTaker must also wake at least every 18 minutes for time keeping, and will not sleep unless it can sleep for at least one full second. Current draw is 120mA while awake and less than 0.4mA while asleep.
The dataTaker has a LED, which flashes when the dataTaker carries out an analog to digital conversion. The Converting LED flashes for a period of time equal to the number of channels being scanned during data acquisition or an autocalibration.
The dataTaker 50 this LED is located near the external power supply screw terminals, while for the dataTaker 500/600 series loggers the LED is located beside the memory card connector.
The Converting LED also flashes every second when the logger is either externally powered, or powered from the internal battery in normal power mode. This flashing coincides with the internal battery current being sampled to determine if the logger should select the low power mode.
The dataTaker has an option for switching off power to the analog input multiplexer while the logger is asleep. This can reduce current draw from the battery, thereby extending battery life.
However removing power reduces the input impedance of the solid state CMOS multiplexers of the dataTaker 50, 500 and 600, from millions of ohms to only a few hundreds of ohms. This can result in excessive current flow from sensors, which may not be acceptable.
The dataTaker 505, 605, 515 and 615 loggers do not have this option.
Switching the Multiplexer Power for the dataTaker 50
The multiplexer powering for the dataTaker 50 is set by switch 4 of the DIP switch located under the top cover. This switch is labelled Power.
When this switch is in the ON position (default), then power is continually applied to the positive side of the multiplexer. The negative side switches from ñ4 Volt to ground in the sleep mode. This option will only safeguard sensors with a positive output relative to ground.
When this switch is in the OFF position, both the positive and the negative multiplexer power supplies are removed while the logger is in the sleep mode.
Switching the Multiplexer Power for the dataTaker 500 dataTaker 600
The dataTaker 500 and 600 multiplexer powering option is selected by a jumper located midway along the memory card side of the top circuit board. The jumper is labelled Mux Power, and has two positions which are labelled as SW (switched) and USW (unswitched).
When the jumper is in the USW position (default), then power is continually applied to the multiplexer.
When the jumper is in the SW position, the multiplexer power is switched off while the logger is in the sleep mode.
Setting the Mains/Line Frequency
The local mains or line frequency is defined to the dataTaker via bit 1 of the DIP switch (See Figure 9). The mains frequency options are 50 Hz for Australia, Europe, Asia, New Zealand, etc, and 60 Hz for Canada and USA.
For 50Hz operation, bit 1 of the DIP switch should be set OFF, while for 60Hz operation bit 1 should be set ON.
The mains frequency setting is used by the analog to digital converter of the dataTaker to synchronize the analog conversion period to the local mains frequency. This maximizes the rejection of noise due to mains or line induced hum.
Figure 9 ñ The Line Frequency DIP Switch