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

Measuring Analog Logic State

The dataTaker supports an Analog State input type, which allows the analog input channels to be used to monitor logic states and contact closures.

When Analog State inputs are sampled, the voltage on the input channel is measured and compared in software with a user definable threshold voltage.

If the measured voltage is greater than or equal to the threshold, then the dataTaker returns a 1 State. If the measured voltage is less than the threshold, then the dataTaker returns a 0 State.

The Analog State inputs cannot be used as counters.

The input voltage for Analog State must be within the voltage measurement range, and common mode voltage range, of the dataTaker.

For dataTaker 50, 500 and 600 which have the solid state multiplexer, the voltage measurement range is ñ2.5 Volts to +2.5 Volts, and the common mode voltage range is ñ3.5 Volts to +3.5 Volts.

For dataTaker 505, 605, 515 and 615 which have the relay multiplexer, the voltage measurement range is ñ100 Volts to +100 Volts, and the common mode voltage range is -100 Volts to +100 Volts.

The dataTaker 50 has 5 differential analog input channels, which can also be used as 10 single ended input channels. The dataTaker 500/600 series loggers and Channel Expansion Module (CEM-AD) have 10 differential analog input channels, which may also be used as 30 single ended input channels.

Any combination of differential and single ended analog input modes can be used for Analog State measurements.

The Analog State inputs together with the true digital channels provide a total of 15 digital channels for the dataTaker 50, 34 digital channels for the dataTaker 500/600 series loggers and 50 digital channels for each Channel Expansion Module (CEM-AD).

Analog State Thresholds

The threshold voltage comparison for the Analog State inputs is performed in software by the dataTaker.

The threshold voltage is specified as a channel option for the Analog State input channels included in schedule lists.

The threshold voltage must be in the range of ñ2500 mV to +2500 mV for dataTaker 50, 500 and 600, and is declared in units of millivolts.

The threshold voltage must be in the range of ñ100 V to +100 V for dataTaker 505, 515, 605 and 615, and is declared in units of volts.

Using DeTransfer, the command for example

3AS(1000)  6AS(24.0,A)

specifies that the Analog States are to be measured as follows

the Analog State voltage measured for analog input channel 3 is compared with a threshold voltage of 1000 mV

the Analog State voltages measured for analog input channels 6 is compared with a threshold voltage of 24.0 V. The channel option A selects in the internal attenuator for the higher voltage range (dataTaker 505, 605, 515 and 615 only)

Using DeLogger, the Analog State threshold is entered into the Analog State Configuration dialog, and Attenuation for dataTaker 505, 605, 515 and 615 loggers is set by clicking the Attenuation button.

 

Each differential or single ended Analog State input signal can be compared to a different threshold if required. The threshold is specified on a channel by channel basis.

If a threshold voltage channel option is not specified, then the threshold voltage defaults to 2500 mV, which is compatible with 5 Volt TTL and CMOS level inputs.

If a threshold voltage of 0 mV is specified, then the Analog State is determined by comparison of the active side of the input signal with its reference as follows

for differential inputs the reference is the voltage applied to the ñve terminal, and the Analog State is determined by the voltage comparison between the +ve and ñve terminals.

for single ended inputs referenced to Analog Return then the reference is the voltage applied to the Analog Return terminal, and the Analog State is determined by a voltage comparison between the input terminal and Analog Return.

for single ended inputs referenced to an external common the reference is the voltage applied to the SE REF terminal, and the Analog State is determined by a voltage comparison between the input terminal and SE REF.

Data is returned for Analog State inputs as digital logic state data as follows

if the voltage applied to the input channel is greater than the specified threshold voltage, then a logic 1 is returned

if the voltage applied to the input channel is less than the specified threshold voltage, then a logic 0 is returned

This logic applies to Analog State voltages which are measured both as differential or single ended inputs.

Measuring Analog State as Differential Inputs

When Analog States are measured as differential inputs, the voltage measured between the +ve and ñve terminals of the analog input channel is compared with the specified threshold voltage.

If the Analog State of high voltage signals is to be measured, then the signal must first be attenuated.

For the dataTaker 50, 500 and 600, attenuation is provided by installing an external attenuator on the input channel. The attenuated input must reduce the high voltage signal to within the range of ±3.5 Volts before connecting to the analog input channels.

High voltage Analog State signals are attenuated using voltage attenuator networks which are described in Section II ñ Measuring High Level Voltages. Both sides of the high voltage signal must be attenuated.

For the dataTaker 505, 605, 515 and 615, attenuation is achieved simply by selecting the internal attenuator resistors. When the internal attenuation resistors are selected, the input voltage range can be ±100 Volts.

Measuring Analog States as Differential Inputs

Analog State voltages are connected to the analog input channels as differential inputs as follows

 

 

Figure 64 ñ Connecting Analog State Voltages as Differential Inputs

 

The differential voltage measured between the +ve and ñve terminals is compared with the specified threshold voltage to determine the analog logic state.

Analog State voltages connected to the analog input channels 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
 RA20M
  1AS  3AS(1500)
END

instructs the dataTaker to measure Analog States as follows

the voltage measured between the +ve and ñve terminals of analog channel 1 is compared with the default threshold of 2500 mV

the voltage measured between the +ve and ñve terminals of analog channel 3 is compared with a threshold of 1500 mV

The AS indicates that the voltages connected to these channels are to be measured for Analog State.

If the threshold voltage is specified as 0 mV, then the Analog State is measured by comparison of the voltage applied to the +ve terminal with the voltage applied to the ñve terminal.

Using DeLogger, differential Analog State signals can be measured by the following Program Builder program.

The differential connections are selected from the Analog State Wiring Configurations dialog which opens when you have selected the analog input channel.

The threshold voltage is entered into the Threshold (mV) field, and applies to this channel only.

If attenuation of the Analog State signal is required, then click the Attenuation button, and enter the appropriate details.

 

Analog State data is returned in units of State. The dataTaker will read the inputs every 20 minutes, and readings are stopped by entering a H (Halt) command.

Measuring Analog State as Single Ended Inputs

Analog State voltages can also be measured as single ended inputs referenced to either Analog Return, or to an external common.

When Analog States are measured as single ended inputs, the voltages measured between the +ve, ñve or ] terminals and the appropriate reference are compared with the specified threshold voltage.

If the Analog State of high voltage signals are to be measured, then the signal must first be attenuated.

For the dataTaker 50, 500 and 600, attenuation is provided by installing an external attenuator on the input channel. The attenuated input must reduce the high voltage signal to within the range of ±3.5 Volts before connecting to the analog input channels.

High voltage Analog State signals are attenuated using voltage attenuator networks which are described in Section II ñ Measuring High Level Voltages. Both sides of the high voltage signal must be attenuated.

For the dataTaker 505, 605, 515 and 615, attenuation is achieved simply by selecting the internal attenuator resistors. When the internal attenuation resistors are selected, the input voltage range can be ±100 Volts.

Single Ended Inputs Referenced to Analog Return

Analog State voltages are connected to the analog input channels as single ended inputs referenced to Analog Return as follows

 

 

Figure 65 ñ Connecting Analog State Voltages as Single Ended Inputs Referenced to Analog Return

 

The voltage measured between the +ve, ñve or T terminals and the Analog Return terminal is compared with the specified threshold voltage to determine the analog logic state.

The dataTaker 50 does not support single ended Analog State measurement for the Excite (T) terminal.

Analog State voltages 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
 RA20S
  1+..2-AS(1000)  8ñAS
END

instructs the dataTaker to measure Analog States as follows

the voltages measured between single ended analog channels 1+ through 2ñ and Analog Return, are compared with a threshold of 1000 mV

the voltage measured between the single ended channel 8ñ and Analog Return is compared with the default threshold of 2500 mV

The AS indicates that the voltages connected to these channels are to be compared for Analog State.

If the threshold voltage is specified as 0 mV, then the Analog State is measured by comparison of the voltage applied to the +ve, ñve or T terminal with the voltage applied to the Analog Return terminal.

Using DeLogger, single ended Analog State signals referenced to Analog Return can be measured by the following Program Builder program.

The single ended connections referenced to Analog Return are selected from the Analog State Wiring Configurations dialog which opens when you have selected the analog input channel.

The threshold voltage is entered into the Threshold (mV) field, and applies to this channel only.

If attenuation of the Analog State signal is required, then click the Attenuation button, and enter the appropriate details.

 

Analog State data is returned in units of State. The dataTaker will read the inputs every 20 seconds, and readings are stopped by entering a H (Halt) command.

Single Ended Inputs Referenced to an External Common

Analog State voltages are connected to the analog input channels as single ended inputs referenced to an external common as follows

 

 

Figure 66 ñ Connecting Analog State Voltages as Single Ended Inputs
Referenced to an External Common

 

The voltage measured between the +ve, ñve or T terminals and the SE REF terminal is compared with the specified threshold voltage to determine the analog logic state.

The dataTaker 50 does not support single ended Analog State measurement for the Excite (T) terminal.

Analog States connected to 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
 R15S
  1+AS(1200,X)  5ñAS(20,X,A)
END

instructs the dataTaker to measure Analog States as follows

the voltage measured between single ended analog channel 1+ and SE REF is compared with a threshold of 1200 mV

the voltage measured between single ended analog channel 5ñ and SE REF is compared with a threshold of ñ20 Volts. The internal attenuator is selected by the channel option A (dataTaker 505, 605, 515 and 615 only)

The AS indicates that voltages connected to these channels are to be read for Analog State. The X channel option specifies that the Analog State voltage is referenced to the SE REF terminal.

If the threshold is specified as 0 mV, then Analog State is measured by comparing the voltage on the +ve, ñve or T terminal with the voltage on the SE REF terminal.

Using DeLogger, single ended Analog State signals referenced to Analog Return can be measured by the following Program Builder program.

 

The single ended connections referenced to Analog Return are selected from the Analog State Wiring Configuration dialog which opens when you have selected the analog input channel.

The threshold voltage is entered into the Threshold (mV) field, and applies to this channel only. If attenuation of the Analog State signal is required, then click the Attenuation button, and enter the appropriate details.

Analog State data is returned in units of State. The dataTaker will read the inputs every 15 seconds, and readings are stopped by entering a H (Halt) command.

Monitoring Contact Closures by Analog State

The Analog State inputs can be used to monitor switch or contact closures.

Each analog input channel can support one contact closure as a differential Analog State input, and two (dataTaker 50) or three (dataTaker 500 and 600 series) contact closures as single ended Analog State inputs (see the previous sections).

The contact closures must switch a voltage, which is measured and compared with the threshold voltage to determine the state of the switch. Contact closures can be excited by two methods as follows

the contact closure can be excited from an external 5 Volt power supply, via pull up resistors of 10 ñ 20 KOhm

an excitation current or voltage can be output from the Excite terminal when the contact closure is monitored

The excitation voltage holds the analog input channel at a 'high' voltage while the contact closure is open. However when the contact closure closes, the short circuit pulls the input to a 'low' voltage.

The voltage measured for the input channel is either compared to the internal 2.5 Volt default threshold voltage, or a user specified threshold voltage. The voltage comparison is carried out in software.

Contact closures can be connected to the analog input channels as differential or single ended inputs.

An open switch contact returns 1 State, and a closed switch contact returns 0 State.

External Excitation and Differential Inputs

Contact closures excited by an external voltage are connected to the analog input channels as differential inputs as follows

 

 

Figure 67 ñ Connecting Externally Excited Contact Closures as Differential Inputs

 

Externally excited contact closures connected as differential inputs are read in the same way as described above under Figure 64.

External Excitation and Single Ended Inputs

Contact closures excited by an external voltage are connected to the analog input channels as single ended inputs as follows

 

 

Figure 68 ñ Connecting Externally Excited Contact Closures as Single Ended Inputs

 

Externally excited contact closures can be connected as single ended inputs referenced to Analog Return or to an external common connected to SE REF.

Externally excited contact closures connected as single ended inputs are read in the same way as described above under Figure 65 and Figure 66.

Excite Terminal Excitation and Differential Inputs

Contact closures are connected to the analog input channels as differential inputs excited by the Excite terminal as follows

 

 

Figure 69 ñ Connecting Contact Closures Excited from the Excite Terminal as Differential Inputs

 

Contact closures excited from the Excite terminal and connected as differential inputs are read as described above under Figure 64. However, to turn on the excite terminal at the time of reading the channel, the channel option V must be added. This turns on a 4.5 Volt source from the Excite terminal.

Using DeTransfer, the command for example

BEGIN
 RA10M
  1AS(V)  5AS(2000,V)
END

instructs the dataTaker to read the contact closures as follows to determine the state of the contacts

the excite terminal is turned on to source 4.5 Volts, and the voltage measured between the +ve and ñve terminals of analog channel 1 is compared with the default threshold of 2500 mV

the excite terminal is turned on to source 4.5 Volts, and the voltage measured between the +ve and ñve terminals of analog channel 5 is compared with a threshold of 2000 mV

The V channel option specifies that the Excite terminal is to output 4.5 Volt when each analog channel is read. Alternatively either the I or II channel option could be used to output a current from the Excite terminal when the contact closure is read.

Using DeLogger, the Excite terminal is programmed to turn on before measurement by selecting Channel Options:ExcitationÖ and clicking Voltage under the Excitation tab.

 

 

 

 

 

 

 

Excite Terminal Excitation Single Ended Inputs

Contact closures excited by the Excite terminal are connected to the analog input channels as single ended inputs as follows

 

 

Figure 70 ñ Connecting Contact Closures Excited from the Excite Terminal as Single Ended Inputs

 

Contact closures excited from the Excite terminal and connected as differential inputs are read as described above under Figure 65 and Figure 66. However, to turn on the excite terminal at the time of reading the channel, the channel option V must be added. This turns on a 4.5 Volt source from the Excite terminal.

Using DeTransfer, the command for example

BEGIN
 RA5M
  1+AS(V)  3ñAS(1800,V)
END

instructs the dataTaker to read the contact closures as follows to determine the state of the contacts

the excite terminal is turned on to source 4.5 Volts, and the voltage measured between the +ve terminal of analog channel 1 and Analog Return is compared with the default threshold of 2500 mV

the excite terminal is turned on to source 4.5 Volts, and the voltage measured between the ñve terminal of analog channel 3 and Analog Return is compared with a threshold of 1800 mV

The V channel option specifies that the Excite terminal is to output 4.5 Volt when each analog channel is read. Alternatively either the I or II channel option could be used to output a current from the Excite terminal when the contact closure is read.

Using DeLogger, the Excite terminal is programmed to turn on before measurement by selecting Channel Options:ExcitationÖ and clicking Voltage under the Excitation tab as illustrated on the previous page.

Error Messages

There are no specific error messages associated with Analog State inputs. However if excitation is not provided, open circuit contacts will return over-range data of ±99999.9 State.

The dataTaker will also report the error condition by the error message ëE11-input(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