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

The dataTaker 50 has 5 digital channels, and the dataTaker 500/600 series loggers have 4 digital channels. The channels are bi-directional TTL/CMOS compatible, and can be used for digital inputs, for digital outputs and for low speed (10 Hz) counting.

The Channel Expansion Module has 20 TTL/CMOS compatible digital input channels, and 10 digital output channels of which 5 are implemented as open collector outputs and 5 are implemented as relays. The digital channels cannot be used for counting.

The digital input channels can be used in a variety of ways as follows

monitoring the logic state of bit inputs

monitoring the logic state pattern of byte inputs

low speed counting to 10 Hz, 16 bit range, presettable (See Section III ñ The Counter Channels)

detecting digital events to trigger Schedules (See Section III ñ Schedules Triggered by Digital Events)

detecting count events to trigger Schedules (See Section III ñ Schedules Triggered by Counter Events)

detecting digital state for conditional trigger (See Section III ñ Schedules Triggered While Condition)

Note 1 :  The digital channels are powered off when the dataTaker is in the low power mode. Therefore the digital input channels cannot be used for counting, or detecting events to trigger Schedules, during low power mode operation.

Note 2 :  The digital channels of the dataTaker are bi-directional, and cannot be used to monitor inputs if they have previously been used as outputs and left switched ON. The channels can be used to monitor digital inputs only if their output state is OFF.

Analog input channels can also be used to monitor digital state. Analog State compares input voltage with a definable threshold to determine logic state. Analog State inputs can be differential or single ended, and cannot be used for counting.

Digital State Inputs

There are several types digital inputs, depending on the type of channel and whether the channels are used as bit or byte inputs. These are detailed in the table below

 

Digital Input Types

   

Number of Channels

 

Input Signal

Input Type Identifier

DT50

DT500

DT600

CEM

Units

Text

Digital Inputs

       

Digital bit

DS

5

4

20

State

Digital byte

DB(mask)

See below

Byte

Analog Inputs

       

Differential

AS(threshold)

5

10

10

State

Single Ended to Analog Return

AS(threshold)

10

30

30

State

Single Ended to SE REF

AS(threshold,X)

10

30

30

State

 

Reading Digital Bit Inputs

Digital bit input channels are specified in a schedule list in the format

nDS

and

n..mDS

where

n              is a single digital channel
n..m          is a sequence of digital channels
DS            is the digital bit input identifier

If the digital input channels are located on a Channel Expansion Module, then the module number precedes the channel number(s).

Using DeTransfer, digital bit input channels are read using the commands for example

BEGIN
 RA1M
  1DS  2DS  1:3..4DS
END

which returns data for the digital bit inputs every minute.

Using DeLogger, digital bit input channels are selected in the Program Builder as follows

 

 

The data returned by reading digital bit inputs is either 1 or 0, indicating whether the input is high or low respectively.

When digital bit inputs are averaged (See Section III ñ Statistical Sub Schedule), data is returned in the range of 0.00 - 1.00. This proportionally represents the number of times that the input was high when sampled during the averaging period. Digital bit averaging can be used as a measure of the duty cycle of the digital inputs.

Reading Digital Byte Inputs

The dataTaker is also able to read the digital input channels as byte inputs. Digital byte inputs are implemented as groups of successive digital bit input channels.

The digital byte command can be used to read groups of digital input channels simultaneously, returning a decimal value representing the bit pattern of digital inputs.

Digital bytes are read beginning at a specified digital input channel number, for the next 8 successive digital inputs. If there are fewer than 8 digital inputs beyond the first digital channel (as will be the case for the dataTaker) then the byte is returned only for those digital channels present.

The digital byte input is specified in a Schedule list by the general format

nDB(mask)

where

n              is the first channel to begin reading the byte
mask         is an optional bit mask of which bit channels are to be
               included in the byte (see below)
DB            is the digital byte input identifier

The digital byte input channel number n is defined as the first digital bit input channel to be read. If the digital input channels are located on a Channel Expansion Module, then the module number precedes the channel number(s).

Using DeTransfer, digital byte inputs are read using the commands for example

BEGIN
 RA1M
  1DB
END

returns the byte for all digital input channels of the dataTaker starting from digital input channel 1, and

BEGIN
 RA1M
  3DB
END

returns the byte for digital input channels 3, 4 and 5 of the dataTaker 50, or digital input channels 3 and 4 of  dataTaker 500/600 series loggers.

Digital Byte Mask

The optional digital byte mask allows individual digital input channels within the group to be selected as follows

channels associated with set bits in the mask are included in the byte input

channels associated with clear bits in the mask are not included in the byte input

The relationship between the bit number in the mask and the digital channels is below

Mask bit         8  7  6  5  4  3  2  1
Channel 1-4      x  x  x  x  4  3  2  1    DT500
Channel 1-8      8  7  6  5  4  3  2  1    CEM
Channel 5-13     12 11 10  9  8  7  6  5    CEM
                    where x indicates ignored bits

The mask is specified as a decimal value equivelent to the required bit pattern. The mask value is the sum of the decimal weighting for each bit, which are as follows

Mask bit           8   7   6   5   4   3   2  1
Decimal weight   128  64  32  16   8   4   2  1

Some examples of mask values and associated bit patterns follow

3        0 0 0 0 0 0 1 1
15       0 0 0 0 1 1 1 1
129      1 0 0 0 0 0 0 1
255      1 1 1 1 1 1 1 1

If a mask is not specified, then the mask defaults to 255 and all channels from the nominated first channel are included in the byte.

The range of the data returned by reading the full byte is as follows

dataTaker 50                                           0 – 31

dataTaker 500/600 series loggers               0 – 15

Channel Expansion Module             0 ñ 255

When digital byte inputs are averaged, data is returned in the range

dataTaker 50                                           0.00 – 31.00

dataTaker 500/600 series loggers               0.00 – 15.00

Channel Expansion Module             0.00 ñ 255.00

This average represents a weighted proportion the number of times that the individual digital inputs were true or high when sampled during the averaging period.

Using DeTransfer, masked digital byte inputs are read using the commands for example

BEGIN
 RA1M
  1DB(7)
END

will return the byte beginning at digital input channel 1, and masks to include the first three channels 1, 2 and 3.

DeLogger does not directly support digital bytes, however these can be read using the User channel in the Program Builder as follows

 

 

Analog State Inputs

The analog input channels of the dataTaker can be used to monitor logic state using the Analog State function.

Differential or single ended input voltage levels are measured and compared to a user definable threshold to determine the logic state.

In contrast to TTL/CMOS compatible logic state inputs where the logic thresholds are <1.5 Volt for 0, and >3.5 Volts for 1, threshold for the Analog State input type is variable and is defined as a voltage in the range of -2500 mV to +2500 mV.

Analog State does not support byte inputs, or counters, and cannot be used to trigger Schedules.

If the input voltage is greater than the ±3.5 Volt common mode range of the dataTaker, then it is treated as a 5 Volt level. For threshold comparison the input is treated as logic 1, and provides compatibility with TTL and CMOS inputs.

Analog State of higher voltages, such as 24VDC industrial logic, can also be measured by externally attenuating the signals before connection to the logger.

Reading Differential Analog State Inputs

When Analog State is to be measured for differential inputs, the voltage is applied between the +ve and ñve terminals of the analog input channel (See Section II - Measuring Analog State).

The measured differential voltage is compared with the threshold voltage which is defined as a channel option for the channel, and the Analog State is evaluated as follows

if the measured voltage is less than the threshold voltage,
then logic 0 is returned

if the measured voltage is greater than or equal to the threshold voltage,
then logic 1 is returned

Differential Analog State input channels are specified in a schedule list by the general formats

nAS(threshold)

and

n..mAS(threshold)

where

n                 is a single differential AS channel
n..m             is a sequence of differential AS channels
AS               is the input signal type identifier
threshold       is the threshold voltage for logic comparison

If the analog input channels are located on a Channel Expansion Module, then the module number precedes the channel number(s).

The threshold voltage must be defined in the range of -2500 mV to +2500 mV. If a threshold voltage is not defined, then the threshold voltage defaults to 2500 mV.

Using DeTransfer, differential Analog States are measured by the commands for example

BEGIN
 RA2M
  1AS  2AS(1000)
END

which instructs the dataTaker to measure analog states every 2 minutes as follows

compare the differential voltage on channel 1 with the default 2500 mV threshold

compare the differential voltage on channel 7 with a threshold of 1000 mV

The dataTaker returns logic 0 if the measured voltage is less than the threshold, and returns 1 if the measured voltage is greater than the threshold. Note that different channels can have different thresholds.

Using DeLogger, differential Analog States can be measured by the following Program Builder program. The analog connection and threshold are defined in the Analog State dialog which opens when you have selected the channel and input type

 

 

Reading Single Ended Analog State Inputs

When Analog State is to be measured for single ended inputs, the voltage is applied between the +ve,
–ve or T terminal of the analog input channel, and the Analog Return (R) or SE REF terminal. (See Section II - Measuring Analog State).

The measured single ended voltage is compared with the threshold voltage, which is defined as a channel option to the channel type, and the Analog State is evaluated as follows

if measured voltage is less than threshold voltage, then logic 0 is returned

if measured voltage is greater than threshold voltage, then logic 1 is returned

Single ended Analog State input channels are specified in a schedule list in the general formats

n T AS(threshold)                         n+AS(threshold)                    nñAS(threshold)

and

nT..mTAS(threshold)                  nT..m+AS(threshold)              nT..mñAS(threshold)
n+..mT AS(threshold)                   n+..m+AS(threshold)              n+..mñAS(threshold)
nñ..mT AS(threshold)                   nñ..m+AS(threshold)               nñ..mñAS(threshold)

where

n                 is a single ended AS channel
n..m             is a sequence of single ended AS channels
T                single ended input between excite and R or SE REF terminals
+                 single ended input between positive and R or SE REF terminals
–                 single ended input between negative and R or SE REF terminals
AS               is the input signal type identifier
threshold       is the threshold voltage for logic comparison

Note that the dataTaker 50 does not support the excite terminal as an input terminal.

If the analog input channels are located on a Channel Expansion Module, then the module number precedes the channel number(s).

Threshold voltage is defined in the range of -2500 mV to +2500 mV. If a threshold is not defined, then the threshold voltage defaults to 2500 mV.

If the single ended Analog State input is referenced to SE REF, then this must be specified as a X (eXternal reference) channel option as follows

n+AS(threshold,X)

If this option is not specified, then the single ended Analog State is measured with respect to Analog Return.

Using DeTransfer, single ended Analog States are measured by commands for example

BEGIN
 RA10M
  1+AS  3+AS(1000)  9-AS(-2500,X)
END

which instructs the dataTaker to measure analog states every 10 minutes as follows

compare the single ended voltage on channel 1+ and Analog Return, with the default 2500 mV threshold

compare the single ended voltage on channel 3+ and Analog Return, with a threshold of 1000 mV

compare the single ended voltage input to channels 9ñ and SE REF with a threshold of ñ2500 mV

Using DeLogger, Analog States can be measured by the following Program Builder program. The analog connection and threshold are defined in the Analog State dialog which opens when you have selected the channel and input type

 

 

Gray Code Conversion

The digital input channels of the dataTaker data loggers also support the Gray code binary system. Gray Code is often used for wind direction indicators and shaft encoders which have multi bit digital outputs.

The principal of Gray code converters is that only one bit-changes for each increment. This eliminates false intermediate codes that could occur in natural binary conversion.

The dataTaker implements Gray code conversion as Intrinsic Function F7, which is attached to a channel variable as a channel option. (See Section III - Scaling Data ñ Polynomials, Spans and Functions)

The following example illustrates programming from DeTransfer for a 6 bit wind direction sensor. Using a dataTaker 50 the 5 digital input channels are used as the first 5 bits of the encoder output, and an analog state is used for 6th bit and is the highest order bit.

BEGIN
S1=0,360,0,63"Deg."   ëSpan signal from 0 to 63
                      ëto 0 to 360 degrees
RA1S
 1DB(=1CV,W)           ëAssign to Chan Variable
 1AS(=2CV,W)           ëAssign to Chan Variable
 3CV(W)=1CV+(2CV*32)   ëCombine 1DB & 1AS
 4CV(W)=3CV(F7)        ëConvert Gray code
 4CV(S1,Wind Dir.")    ëApply Span
END

Channel Expansion Modules have 2 full 8 bit byte channels available.  Therefore a 6 or 8 bit Gray code can be read directly. However if a 6 bit Gray code is used, then the 7th & 8th bits must be grounded or the first 6 bits masked by 63 (00111111).

Digital Event Inputs

The digital input channels of the dataTaker can also be used to detect external digital events, which can then be used to trigger Schedules.

A digital event may be defined to be a negative transition, a positive transition, or both. The use of digital events for triggering Schedules is discussed in Section III - Schedules Triggered by Digital Events.

The digital input channels of the Channel Expansion Modules cannot be used to trigger Schedules.

Digital While Inputs

The digital input channels of the dataTaker can also be used to monitor external digital conditions, and use these conditions to control the triggering of Schedules only while the particular digital input is true or high.

Use of digital input channels for conditional triggering of Schedules is discussed in Section III - Schedules Triggered While Condition.

The digital input channels of the Channel Expansion Modules cannot be used for conditional scheduling.

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