dataTaker - Data Loggers, Powerful and Flexible Data Acquisition & Data Logging Systems

Measuring Temperature with Integrated Circuit Temperature Sensors

The dataTaker directly supports the range of integrated circuit (IC) temperature sensors.

IC temperature sensors can be used for measuring temperatures in the environmental and biological range of ñ50 Deg C to +150 Deg C.

There are four basic types of IC temperature sensors, according to the output signal produced in response to sensed temperature, as follows

Analog Devices AD590/592 series temperature sensor, which produces a linear current output
 of 1 µA/Deg K

National Semiconductor LM335 temperature sensor, which produces a linear voltage output
 of 10 mV/Deg

National Semiconductor LM34 temperature sensor, which produces a linear voltage output of
 10 mV/Deg F

National Semiconductor LM35 temperature sensor, which produces a linear voltage output of
 10 mV/Deg C

The dataTaker 50 can measure up to 5 IC temperature sensors as differential inputs, and up to 10 IC temperature sensors as single ended inputs.

The dataTaker 500/600 series loggers and the Channel Expansion Module (CEM-AD) can measure up to 10 of the IC temperature sensors as differential inputs, and up to 30 IC temperature sensors as single ended inputs.

Powering and Connecting IC Temperature Sensors

The IC temperature sensors can either be powered from external power sources, or can be powered directly from the Excite terminals of the analog input channels of the dataTaker.

When powered from the Excite terminal, the sensors are powered for 30 mS during the period of measurement. This has the benefit of reducing self heating effects on the sensors by continuous currents flowing through them from external power supplies.

IC temperature sensors can be connected to the analog input channels of the dataTaker in a number of different ways depending on powering arrangement, as follows

when the sensors are powered from the Excite terminals, the signal can be connected to the analog channels as differential inputs or as +ve and ñve terminal single ended inputs

when the sensors are powered from external sources, the signal can be connected to the analog input channels as differential inputs or as +ve, –ve and T terminal single ended inputs

Each of these methods of connection and powering is discussed for each of the IC temperature sensors in the sections below.

Readings from the IC temperature sensors is returned in units of temperature defined by the setting of the Parameter36 command (See Section II ñ Measuring Temperature).

The Analog Devices AD590/592 Sensor

The Analog Devices AD590/592 is a two terminal IC temperature transducer which produces an output current proportional to absolute temperature. The AD590 is rated for use over the temperature range of ñ55 Deg C to +150 Deg C.

At power supply voltages between 4 to 12 Volt, the AD590 acts as a high impedance constant current regulator, and passes a current of 1 µA/Deg K. The thin film resistors on the IC deviceís chip are laser trimmed to calibrate the device to 298.2 µA output at 298.2 Deg K (25 Deg C).

The AD590 is particularly useful for remote temperature sensing applications, because the sensor delivers an output current which is insensitive to voltage drops over long cables. Any well insulated twisted pair cable is sufficient for operation hundreds of feet from the dataTaker.

For detailed specifications of the AD590, refer to the Analog Devices Data Acquisition Handbook ó Volume 1 Integrated Circuits (1984).

The current signal from the AD590 temperature sensor can be connected to the analog input channels of the dataTaker in any of the configurations for current measurement described in Section II ñ Measuring Current.

The AD590 is available in a number of tolerances or grades. The accuracy of different grades varies between ±1 Deg C and ±5 Deg C. A calibration factor to correct sensor accuracy can be specified by adjusting the shunt resistance channel option.

Using DeTransfer, the specification for example

8#AD590(100.3)

instructs the dataTaker to apply a calibration factor of 0.3 to the shunt resistance to correct the AD590 sensor measured on channel 8.

Using DeLogger, the calibration factor/shunt resistor adjustment can be entered into the AD Series Wiring Configuration which opens when you have selected the analog channel

 

 

The AD590 is supported by the dataTaker in a number of ways as follows

the sensor can be powered from the Excite terminal of the analog input channels, or be externally powered

the current signal from the sensor can be measured using the internal current shunt within the analog channels, or by using external current shunts.

When using external current shunts, the voltage across the shunt can be connected to the analog input channels as differential or single ended inputs.

These options provide a variety of ways in which the AD590 temperature sensor can be connected to the dataTaker. The most commonly used connections are described in the sections below.

AD590 Directly Powered and Measured Using Internal Shunts

The AD590 temperature sensor can be powered from the Excite terminal of the analog input channels, and the current signal from the sensor measured across the internal current shunt between Analog Return and GND.

This is the most commonly used and simplest connection method.

The AD590 sensors are connected directly to the analog input channels between the Excite terminal and the Analog Return terminal.

The connection for AD590 sensors powered from the Excite terminal and measured using the internal current shunts is illustrated below.

 

 

Figure 82 ñ Connection of AD590 Sensors Powered from the Excite Terminal
and Measured Using Internal Shunts

 

The unused +ve and ñve terminals of channels monitoring the AD590 sensors can be used for other differential and single ended inputs.

AD590 temperature sensors powered directly from the Excite terminals and measured using the internal current shunts are sampled and the data is returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA5M
  1#AD590  5#AD590
END

instructs the dataTaker to measure the current signals from the AD590 sensors connected to analog input channels 1 and 5, using the internal shunts.

The AD590 specifies that the signals applied to these channels are from AD590 sensors.

The AD590 channel type defaults to Excite terminal powering, and so an Excite terminal channel option does not have to be specified.

The # indicates that the current signal is input to the Analog Return terminal, and is to be measured across the internal current shunt.

Using DeLogger, AD590 sensors that are connected for direct powering are measured by the following Program Builder program.

The connection is selected from the AD Series Wiring Configurations dialog which opens when you have selected the analog input channel.

 

 

The data is returned in units of temperature.

The dataTaker will read the sensors every 5 minutes, and readings are stopped by entering a H (Halt) command.

AD590 Directly Powered and Measured Using External Shunts

The AD590 temperature sensor can be powered from the Excite terminal, and the current signal from the sensor measured across external current shunts.

The voltage produced across the external shunts by the sensor output current can be measured as differential or single ended inputs (See Section III ñ Measuring Currents).

 

 

Figure 83 ñ Connection of AD590 Sensors Powered from the Excite Terminal
and Measured Using External Shunts

The connection for AD590 sensors which are powered from the Excite terminal and are measured using external current shunts connected as differential and single ended inputs are illustrated above. The upper schematic is for a differential connection of the shunt resistor, and the lower is for a single ended connection of the shunt resistor.

The external shunt is assumed to have a resistance of 100 Ohms. If a different shunt resistance is used, then the resistance is declared as a channel option (see above).

AD590 sensors powered directly from the Excite terminals and measured using the external current shunts are sampled and the data is returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA5M
  1AD590  3+AD590  3ñAD590
END

instructs the dataTaker to measure

the current signal from the AD590 sensor connected as a differential input to the +ve and ñve terminals of channel 1

the current signal from the AD590 sensor connected as a single ended input to channel 3+ and Analog Return

the current signal from the AD590 sensor connected as a single ended input to channel 3ñ and Analog Return

using external shunts

The AD590 specifies that the signals applied to these channels are from AD590 sensors. The AD590 channel type defaults to Excite terminal powering, and so powering does not have to be specified.

Using DeLogger, AD590 sensors that are connected for direct powering and external shunts are measured by the following Program Builder program. The connection is selected from the AD Series Wiring Configurations dialog which opens when you have selected the analog input channel.

 

 

Note: The sensor powering from the Excite terminal is not shown in these icons.

The data is returned in units of temperature.

The dataTaker will read the sensors every 5 minutes, and readings are stopped by entering a H (Halt) command.

AD590 Externally Powered and Measured Using External Shunts

The AD590 temperature sensors can be powered from an external power supply of 4 to 12 Volt, or from the 5 Volt switched sensor power supply of the dataTaker.

The current signal from the sensor can be measured using external current shunts that are connected to the analog input channels as differential or single ended inputs.

Single ended inputs can be referenced to Analog Return, or can be referenced to an external common which is connected to the SE REF input terminal.

Differential Inputs

The AD590 temperature sensors can be powered from an external 4 to 12 Volt power supply. The current signal from the sensor is measured using external current shunts connected to the analog input channels as differential inputs.

The current shunt is assumed to have a resistance of 100 Ohms. If a different shunt resistance is used, then this must be declared as a channel option (see above).

The connection for externally powered AD590 sensors using external current shunts and differential inputs is illustrated below

 

 

Figure 84 ñ Connection of Externally Powered AD590 Sensors Using External Shunts
and Differential Inputs

 

Using DeTransfer, the command for example

BEGIN
 RA10S
  3AD590(N)  5AD590(N)
END

instructs the dataTaker to measure the current signals from AD590 sensors connected to analog input channels 3 and 5, from external shunts.

The AD590 specifies that the signals applied to these channels are from AD590 sensors. The AD590 channel type defaults to Excite terminal powering, and so the channel option N should be specified to disable output from the Excite terminal.

Using DeLogger, AD590 sensors connected for external powering and differentially connected external shunts are measured by the following Program Builder program. The differential connection is selected from the AD Series Wiring Configurations dialog which opens when you select the analog input channel.

 

 

Note: The sensor powering from the Excite terminal is not shown in these icons.

The data is returned in units of temperature.

The dataTaker reads sensors every 10 seconds, and readings are stopped by a H (Halt) command.

Single Ended Inputs Referenced to Analog Return

The AD590 temperature sensor can be externally powered from an external 4 to 12 Volt power supply, and the current signal from the sensor measured using external current shunts connected to the analog input channels as single ended inputs. The single ended inputs can be referenced to Analog Return (See Section II ñ Measuring Currents).

The current shunt is assumed to have a resistance of 100 Ohms. If a different shunt resistance is used, then this must be declared as a channel option (see above).

The connection of externally powered AD590 sensors using external shunts and single ended inputs referenced to Analog Return is illustrated below

 

 

Figure 85 ñ Connection of Externally Powered AD590 Sensors Using External Shunts
and Single Ended Inputs Referenced to Analog Return

By using the Excite terminal as an input, the dataTaker 500/600 series loggers are able to monitor up to 30 AD590 sensors connected as single ended inputs referenced to Analog Return.

The dataTaker 50 does not support the Excite terminal as an input, and can only monitor up to 10 sensors.

Externally powered AD590 temperature sensors using external shunts connected to the analog input channels as single ended inputs referenced to Analog Return are sampled and the data is returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA10M
  8ñAD590(N)  10+AD590(68,N)
END

instructs the dataTaker to measure the current signal from the AD590 sensors

using 100 Ohm external shunts connected between single ended analog channels 8ñ and Analog Return

using a 68 Ohm external shunt connected between single ended analog channel 10+ and Analog Return.

The AD590 specifies that the signals applied to these channels are from AD590 sensors. The AD590 channel type defaults to Excite terminal powering, and so the channel option N should be specified to disable output from the Excite terminal.

Using DeLogger, AD590 sensors connected for external powering and external shunts connected as single ended inputs are measured by the following Program Builder program. The single ended connection is selected from the AD Series Wiring Configurations dialog which opens when you have selected the analog input channel.

 

 

Note: The sensor powering from the Excite terminal is not shown in these icons.

The data is returned in units of temperature.

The dataTaker will read the sensors every 10 minutes, and readings are stopped by entering a H (Halt) command.

Single Ended Inputs Referenced to an External Common

Remotely located AD590 temperature sensors powered from an external power supply and using external current shunts, can be measured with respect to an external common reference point which is connected to the SE REF terminal.

The external current shunt is assumed to have a resistance of 100 Ohms. If a different shunt resistance is used, then the shunt resistance must be declared as a channel option (see above).

The connection of externally powered AD590 sensors using external current shunts and single ended inputs referenced to an external common is illustrated below

 

 

Figure 86 ñ Connection of Externally Powered AD590 Sensors Using External Shunts
and Single Ended Inputs Referenced to an External Common

 

Up to 15 AD590 sensors can be connected to the dataTaker 50 in this way, and up to 40 AD590 sensors can be connected to the dataTaker 500/600 series loggers.

Externally powered AD590 temperature sensors using external shunts connected to the analog input channels as single ended  inputs referenced to an external common are sampled and the data is returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA10M
  6ñAD590(N,X)
END

instructs the dataTaker to measure the current from the AD590 sensors using an external 100 Ohm shunt connected between single ended analog input 6ñ and SE REF.

The AD590 specifies that the signals applied to these channels are from AD590 sensors. The AD590 channel type defaults to Excite terminal powering, and so the channel option N should be specified to disable output from the Excite terminal. The X channel option indicates that the single ended inputs are to be measured between the input terminal and SE REF. The data is returned in units of temperature.

The dataTaker will read the inputs every 10 minutes, and readings are stopped by entering a H (Halt) command.

DeLogger does not directly support this method for measuring AD590 temperature sensors. However the User channel type (DeLogger Version 4.2.15 or later) can be used, and the channel specifications shown above for DeTransfer can be entered.

The National Semiconductor LM335 Sensor

The National Semiconductor LM135/LM235/LM335 series of IC temperature sensors operate as 2 terminal zener diodes with a breakdown voltage directly proportional to absolute temperature at +10 mV/Deg K. These sensors measure temperatures within the range ñ55 Deg C to +150 Deg C.

When calibrated at 25 Deg C the LM335 series typically has an error of up to ±3 Deg C, depending on the grade of the sensor.

However the sensor has provision for calibration adjustment. A trim potentiometer of 20 - 50 KOhm can be connected across the LM335, with the wiper connected to the Adjust pin. This allows for a single point calibration of the device.

For detailed specifications of the LM335 series, refer to the National Semiconductor Linear Databook (Vol 2).

The LM335 temperature sensor outputs +10 mV/Deg K, and so at the maximum temperature range of 150 Deg C (423 Deg K) the sensor will output 4.23 Volts. This exceeds the voltage input range of the dataTaker, and so the signal must be attenuated before input to the analog channels if the full temperature range is to be used. The dataTaker assumes that the LM335 voltage signal is attenuated by a factor of 2.

A calibration factor to correct sensor accuracy and tolerance of the attenuation resistors can be specified as a channel option.

Using DeTransfer, the command for example

6LM335(2.13)

instructs the dataTaker to apply a calibration factor of 0.13 to the LM335 sensor measured on analog channel 6. The calibration factor defaults to 2.0 which is the required input attenuation.

Using DeLogger, the calibration factor can be entered into the LM Series Wiring Configuration which opens when you have selected the analog channel

 

 

The LM335 is supported by the dataTaker in a number of ways as follows

the sensor can be powered from the Excite terminal of the analog input channels, or can be externally powered

the voltage signal from the sensor can be connected to the analog input channels as differential or single ended inputs

The voltage signal from the LM335 temperature sensor can be connected to the analog channels of the dataTaker in any configuration for high level voltage measurement described in Section II ñ Measuring High Level Voltages.

The most commonly used connections are described in the sections below.

LM335 Directly Powered

LM335 temperature sensors can be powered directly from the Excite terminal of the dataTaker, and the output voltage from the sensor measured either as differential or single ended inputs.

The single ended inputs can be referenced to Analog Return or to an external common connected to SE REF.

The upper temperature measurement range for LM335 sensors powered from the Excite terminal is limited to 70 Deg C because the voltage output from the Excite terminal is not sufficient to drive the sensor over its full temperature measurement range.

Up to 10 LM335 sensors can be connected to the dataTaker 500/600 series loggers as differential inputs, and up to 30 as single ended inputs.

Up to 5 LM335 sensors can be connected to the dataTaker 50 as differential inputs, and up to 10 as single ended inputs

Differential Input

The connection for LM335 sensors powered from the Excite terminal and measured as differential inputs is illustrated below.

 

 

Figure 87 ñ Connection of LM335 Sensors Powered from the Excite Terminal
and Differential Inputs

 

The attenuation resistors can either be located with the sensor, or connected across the terminals of the analog channel.

The fourth wire between Analog Return and the bottom of the sensor can be replaced by a link between the Analog Return and ñve terminals. However if cable resistance is significant, then accuracy will be reduced.

LM335 temperature sensors powered directly from the Excite terminals and measured as differential inputs are sampled and the data is returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA2M
  2LM335  4LM335
END

instructs the dataTaker to measure the voltage signals from an LM335 sensor differentially connected to analog channels 2 and 4.

The LM335 specifies that the voltage applied to this channel is from an LM335 sensor.

The LM335 channel type defaults to Excite terminal powering, and so powering does not have to be specified.

Using DeLogger, LM335 sensors powered from the Excite terminal and connected as differential inputs are measured by the following Program Builder program. The single ended connection is selected from the LM Series Wiring Configurations dialog which opens when you have selected the analog input channel.

 

 

The data is returned in units of temperature.

The dataTaker will read the sensors every 2 minutes, and readings are stopped by entering a H (Halt) command.

Single Ended Inputs

LM335 sensors powered from the Excite terminals can be measured as single ended inputs referenced to Analog Return or to an external common connected to SE REF.

However these connections are not normally used because of the limited maximum temperature range due to the limited drive voltage available from the Excite terminal, and so are not described here.

LM335 Externally Powered

The LM335 temperature sensor can be externally powered from a power supply greater than 4 Volts.

The output signal voltage can be measured as a differential input, or as a single ended input referenced to Analog Return or external common connected to SE REF terminal.

To reduce self heating of the sensor, a series resistor should be included in the power supply circuit to limit current to between 0.5 and 1.0 mA. The resistance of the current limiting resistor depends on the voltage of the external power supply.

The external power can be switched off between readings by a relay that is controlled by the Schedule used to scan the LM335 sensors.

Up to 10 LM335 sensors can be connected to the dataTaker 500/600 series loggers as differential inputs, and up to 30 as single ended inputs.

Up to 5 LM335 sensors can be connected to the dataTaker 50 as differential inputs, and up to 10 as single ended inputs

Differential Input

The LM335 temperature sensor can be externally powered from any power supply greater than 4 Volts, and the output signal voltage can be measured as a differential input.

The connection of externally powered LM335 sensors measured as differential inputs is illustrated below

 

 

Figure 88 ñ Connection of Externally Powered LM335 Sensors as Differential Inputs

 

Externally powered LM335 temperature sensors connected as differential inputs are sampled and the data is returned when a Schedule containing the channel is executed.

The command for example

BEGIN
 RA10S
  3LM335(N)  7LM335(N)
END

instructs the dataTaker to measure the voltage signals from the LM335 sensors differentially connected to analog channels 3 and 7.

The LM335 specifies that the signals applied to these channels are from LM335 sensors.

The LM335 channel type defaults to Excite terminal powering, and so the channel option N should be specified to disable output from the Excite terminal.

The data is returned in units of temperature.

The dataTaker will read the sensors every 10 seconds, and readings are stopped by entering a H (Halt) command.

DeLogger does not directly support this method for measuring LM335 temperature sensors. However the User channel type (DeLogger Version 4.2.15 or later) can be used, and the channel specifications shown above for DeTransfer can be entered.

Single Ended Inputs Referenced to Analog Return

The LM335 temperature sensor can be externally powered from a power supply greater than 4 Volts, and the voltage signals measured as single ended inputs referenced to Analog Common.

The connection of externally powered LM335 sensors as single ended inputs referenced to Analog Return is illustrated below

 

 

Figure 89 ñ Connection of Externally Powered LM335 Sensors as Single Ended Inputs Referenced to Analog Return

 

Externally powered LM335 temperature sensors connected as single ended inputs referenced to Analog Return are sampled and data returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA8M
  3+LM335(N)  3-LM335(N)
END

instructs the dataTaker to measure the voltage signals from the LM335 sensors which are connected as single ended inputs between analog channel 3+ and Analog Return, and channel 3ñ and Analog Return.

The LM335 specifies that the signals applied to these channels are from LM335 sensors. The LM335 channel type defaults to Excite terminal powering, and so the channel option N should be specified to disable output from the Excite terminal.

The data is returned in units of temperature. The dataTaker will read the sensors every 8 minutes, and readings are stopped by entering a H (Halt) command.

DeLogger does not directly support this method for measuring LM335 temperature sensors. However the User channel type (DeLogger Version 4.2.15 or later) can be used, and the channel specifications shown above for DeTransfer can be entered.

Single Ended Inputs Referenced to an External Common

The LM335 temperature sensor can be externally powered from any power supply greater than 4 Volts, and the voltage signals measured as single ended inputs referenced to an external common which is connected to the SE REF input terminal.

 

 

Figure 90 ñ Connection of Externally Powered LM335 Sensors as Single Ended Inputs
Referenced to an External Common

 

The connection of externally powered LM335 sensors as single ended inputs referenced to an external common is illustrated above. The grounded ends of the LM335 temperature sensor voltage signals are connected to a common external reference point, which is in turn connected to the SE REF terminal.

Externally powered LM335 sensors connected as single ended inputs referenced to an external common are sampled and the data is returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA2M
  1ñLM335(N,X)
END

instructs the dataTaker to measure the voltage signal from the LM335 sensor which is connected as a single ended input between analog channels 1ñ and SE REF.

The LM335 specifies that the signals applied to these channels are from LM335 sensors. The LM335 channel type defaults to Excite terminal powering, and so the channel option N should be specified to disable output from the Excite terminal. The X channel option indicates that the single ended inputs are to be measured between the input terminal and SE REF.

The data is returned in units of temperature. The dataTaker will read the sensors every 2 minutes, and readings are stopped by entering a H (Halt) command.

DeLogger does not directly support this method for measuring LM335 temperature sensors. However the User channel type (DeLogger Version 4.2.15 or later) can be used, and the channel specifications shown above for DeTransfer can be entered.

The National Semiconductor LM34 and LM35 Sensors

The National Semiconductor LM34 and LM35 temperature sensors are precision integrated circuit devices, with output voltages which are linearly proportional to temperature as follows

LM34          10 mV/Deg F
LM35          10 mV/Deg C

The LM34 temperature sensor measures temperatures in the range of –70 Deg F to +300 Deg F.

The LM35 temperature sensor measures temperatures in the range of –55 Deg C to +155 Deg C.

The LM34 and LM35 sensors do not have facilities to directly adjust calibration accuracy. These sensors are available in several grades of different accuracy, varying from ±0.2 Degrees to ±2.0 Degrees.

For detailed specifications of the LM34 and LM35 series of IC temperature sensors, refer to the National Semiconductor Linear Supplement (1984).

A calibration factor to correct sensor accuracy can be specified as a channel option.

Using DeTransfer, the command for example

2LM35(1.09)

instructs the dataTaker to apply a calibration factor of 1.09 to the LM35 sensor measured on channel 2.

Using DeLogger, the calibration factor can be entered into the LM Series Wiring Configuration which opens when you have selected the analog channel

 

 

The LM34 and LM35 temperature sensors are supported by the dataTaker as follows

powered from the Excite terminal of the analog channels, or be externally powered

voltage signal can be connected to analog channels as differential or single ended

These options provide a variety of ways in which the LM34 and LM35 temperature sensors can be connected to the dataTaker. The most commonly used connections are described in the sections below.

LM34 and LM35 Directly Powered

LM34 and LM35 temperature sensors can be powered from the Excite terminal, and the output voltage measured either as differential or single ended inputs. Single ended inputs can be referenced to Analog Return or external common connected to SE Ref.

However the temperature measurement range for the LM34 and LM35 sensors is limited to approximately 5 Deg F and 10 Deg C respectively by this configuration, due to a lack of pull down voltage capacity.

Differential Input

LM34 and LM35 temperature sensors can be powered directly from the Excite terminal, and the output voltage from the sensors measured as differential inputs.

 

Figure 91 ñ Connection of LM34 and LM35 Sensors Powered from the
Excite Terminal as Differential Inputs

 

The link between Analog Return and the ñve terminal can be replaced by a fourth lead wire connected between the sensor and the ñve terminal, to improve accuracy.

LM34 and LM35 temperature sensors powered directly from the Excite terminals and measured as differential inputs are sampled and data returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA5M
  1..2LM35
END

instructs the dataTaker to measure the voltage from LM35 sensors connected to channels 1 and 2.

The LM35 specifies the sensor attached to these channels. The LM35 channel type defaults to Excite terminal powering, and so powering does not have to be specified.

Using DeLogger,

 

LM34 and LM35 temperature sensors powered from the Excite terminal and connected as differential inputs are measured by the Program Builder program below.

The differential connection is selected from the LM Series Wiring Configurations dialog which opens when you have selected the analog input channel.

The data is returned in units of temperature. The dataTaker will read the sensors every 5 minutes, and readings are stopped by entering a H (Halt) command.

Single Ended Inputs Referenced to Analog Return

LM34 and LM35 temperature sensors can be powered directly from the Excite terminal of the dataTaker, and the output voltage from the sensors measured as single ended inputs referenced to Analog Return.

The connection is illustrated below

 

 

Figure 92 ñ Connection of LM34 and LM35 Sensors Powered from the Excite Terminal as Single Ended Inputs Referenced to Analog Return

 

LM34 and LM35 temperature sensors powered directly from the Excite terminals and measured as single ended inputs referenced to Analog Return are sampled and the data is returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA5M
  1+..2-LM35
END

instructs the dataTaker to measure the voltage signals from LM35 sensors differentially connected to channels 1+ through 2ñ.

The LM35 specifies that the signals applied to these channels are from LM35 sensors respectively.

The LM35 channel type defaults to Excite terminal powering, and so powering does not have to be specified.

Using DeLogger, LM34 and LM35 sensors powered from the Excite terminal and connected as single ended inputs referenced to Analog Common are measured by the following Program Builder program.

The single ended connection is selected from the LM Series Wiring Configurations dialog which opens when you have selected the analog input channel.

 

 

The data is returned in units of temperature.

The dataTaker will read the sensors every 5 minutes, and readings are stopped by entering a H (Halt) command.

Single Ended Inputs Referenced to an External Common

LM34 and LM35 temperature sensors can be powered directly from the Excite terminal of the dataTaker, and the output voltage from the sensors measured as single ended inputs referenced to an external common connected to SE REF.

The connection is as follows

 

 

Figure 93 ñ Connection of LM34 and LM35 Sensors Powered from the Excite Terminal as Single Ended Inputs Referenced to an External Common

LM34 and LM35 sensors connected as single ended inputs referenced to an external common, and powered from the Excite terminal, are sampled and data is returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA5M
  1+..2-LM35(X)
END

instructs the dataTaker to measure the voltage signals from LM35 sensors differentially connected to channels 1+ through 2ñ.

The LM35 specifies the signals are from LM35 sensors. The LM35 channel type defaults to Excite terminal powering, and so powering does not have to be specified. The X channel option indicates that the single ended inputs are to be measured between the input terminal and SE REF.

The data is returned in units of temperature. The dataTaker will read the sensors every 5 minutes, and readings are stopped by entering a H (Halt) command.

DeLogger does not support this method of measuring LM34 and LM335 IC temperature sensors. However the User channel type (DeLogger Version 4.2.15 or later) can be used, and the channel specifications shown above for DeTransfer can be entered.

LM34 and LM35 Externally Powered

The LM34 and LM35 temperature sensors can be externally powered from any 4 to 30 Volt power supply, and the output voltage measured as differential inputs, or as single ended inputs referenced to Analog Return or to an external common connected to SE REF.

The power supply can be an external power source, or can be from the 5 Volt switched sensor power supply of the dataTaker. The LM34 and LM35 temperature sensors cannot drive voltages near or below their ground pin (corresponding to 0 Deg F for the LM34 and ñ18 Deg C for the LM35).

Therefore the pull down arrangement shown in Figure 94 must be used. This functions by elevating the negative pin voltage by the two diode drops (approximately 1.2 Volts), and pulling the output below the negative pin when necessary.

Differential Input

The LM34 and LM35 temperature sensors can be externally powered from any 4 to 30 Volt power supply, and the output voltage measured as differential inputs.

The connection is illustrated below

 

 

Figure 94 ñ Connection of Externally Powered LM34 and LM35 Sensors
as Differential Inputs

Note :  The circuit also shows a 2K2 series resistor, which may be necessary on long cable runs to prevent oscillation.

Externally powered LM34 or LM35 temperature sensors which are connected as differential inputs are sampled and the data is returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA10S
  3LM34(N)..5LM34(N)
END

instructs the dataTaker to measure the voltage signals from the LM34 sensors differentially connected to channel 3 and channel 5.

The LM34 specifies that the signals applied to these channels are from LM34 sensors respectively, and the data is returned in units of temperature. The LM34 channel type defaults to Excite terminal powering, and so the channel option N should be specified to disable output from the Excite terminal.

The dataTaker will read the sensors every 10 seconds, and readings are stopped by entering a H (Halt) command.

DeLogger does not support this method of measuring LM34 and LM335 IC temperature sensors. However the User channel type (DeLogger Version 4.2.15 or later) can be used, and the channel specifications shown above for DeTransfer can be entered.

Single Ended Inputs Referenced to an External Common

Remotely located LM34 and LM35 temperature sensors which are powered from an external power supply can be measured as single ended inputs referenced to an external common.

The grounded ends of the LM34 and LM35 temperature sensor voltage signals are connected to a common external reference point, which is in turn connected to the SE REF terminal.

The connection of externally powered LM34 and LM35 sensors as single ended inputs referenced to an external common is illustrated below

 

 

Figure 95 ñ Connection of Externally Powered LM34 and LM35 Sensors
as Single Ended Inputs Referenced to an External Common

 

Externally powered LM34 or LM35 temperature sensors which are connected as single ended inputs referenced to an external common are sampled and the data is returned when a Schedule containing the channel is executed.

Using DeTransfer, the command for example

BEGIN
 RA30M
  5+LM35(N,X)
END

instructs the dataTaker to measure the voltage signal from the LM35 sensor connected between channels 5+ and an external common reference connected to SE REF.

The LM35 specifies that the signals applied to these channels are from LM35 sensors respectively. The LM35 channel type defaults to Excite terminal powering, and so the channel option N should be specified to disable output from the Excite terminal. The X channel option indicates that the single ended inputs are to be measured between the input terminal and SE REF.

The data is returned in units of temperature. The dataTaker will read the sensors every 30 minutes, and readings are stopped by entering a H (Halt) command.

DeLogger does not support this method of measuring LM34 and LM335 IC temperature sensors. However the User channel type (DeLogger Version 4.2.15 or later) can be used, and the channel specifications shown above for DeTransfer can be entered.

Error Messages

There are no specific error messages for the IC temperature sensors supported by the dataTaker. Nonetheless, temperature readings outside of the temperature range of ñ55 Deg C to +150 Deg C can be considered suspect.

Input voltage signals which fall outside the range of ±3250 mV, or current signals which fall outside the range of ±25 mA, will produce the error message ëE11ñinput(s) out of rangeí if the Messages Switch /M is enabled.

Page Content


Home

Title and Waranty

Go to: Section 2 | Section 3

Section 1


Construction of the dataTaker 50

Construction of the dataTaker 500 600

Construction of the CEM

Getting Started

 

Section 2


Interfacing

Powering the dataTaker

Powering Sensors from the dataTaker

The Serial Interfaces

The RS232 COMMS Serial Interface

The NETWORK Interface

Analog Process

Connect Analog

Analog Chns

Measuring Low Level Voltages

Measuring High Level Voltages

Measuring Currents

Measuring 4-20mA Current Loops

Measuring Resistance

Measuring Frequency and Period

Measuring Analog Logic State

Measuring Temperature

Measuring Temperature with Thermocouples

Measuring Temperature with RTDs

Measuring Temperature with IC Temperature Sensors

Measuring Temperature with Thermistors

Measuring Bridges and Strain Gauges

Measuring Vibrating Wire Strain Gauges

The Digital Input Channels

Monitoring Digital State

The Low Speed Counters

The Phase Encoder Counter

The High Speed Counters

The Digital Output Channels

The Channel Expansion Module

Installing The Panel Mount Display

 

Section 3


Programming the dataTaker

Communication Protocols and Commands

Entering Commands and Programs

Format of Returned Data

Specifying Channels

The Analog Input Channels

The Digital Input Channels

The Counter Channels

The Digital Output Channels

The Real Time Clock

The Internal Channels

Channel Options

Schedules

Alarms

Scaling Data - Polynomials, Spans and Functions

CVs Calcs and Histogram

Logging Data to Memory

Programming from Memory Cards

STATUS RESET TEST

Switches and Parameters

Networking

Writing Programs

Keypad and Display

Error Mess Text

Appendix A - ASCII

Appendix B - ADC Timing