The dataTaker normally returns data to the host computer in the Free Format Mode. This is a descriptive or conversational style, which is suitable for displaying data directly on a terminal screen such as DeTransfer, for printing data, and for passing data to purpose written and third party data acquisition software packages. The Free Format Mode has a default format for returned data that can be changed using a variety of data formatting commands to suit particular applications. The dataTaker also has an alternative mode for returned data, designed for transferring data to purpose written and third party data acquisition packages. This is the Fixed Format Mode, which is a fixed data format that cannot be changed by the user. This mode is detailed in the dataTaker Advanced Communications Manual. The format mode for returned data is selected by the Data Format Switch as follows /HSelect Fixed Format Mode Following initial power up, a hardware reset, or a RESET command, the Free Format Mode is selected. DeTransfer interfaces to the dataTaker in either data format mode, however the Free Format Mode is generally preferred. DeLogger supervises the dataTaker in the Fixed Format Mode. DeLogger forces the logger to Fixed Format Mode during connection, and returns it to Free Format Mode during disconnection. The data formatting discussed in this chapter is in the main not appropriate for use with DeLogger. The Free Format Mode for returned data is described below, including commands for defining the various data formats. Controlling the Return of DataThe return of data from the dataTaker to a host computer or terminal as the input channels are read and calculations performed can be enabled or disabled using the Return Data Switch as follows /R Enables return of data to the host (Default) The Return Data Switch defaults to /R whenever the dataTaker is initially powered up, hardware reset or executes a RESET command. Return of data can be disabled when operating the logger standñalone, and data is logged to data memory or a memory card. This conserves battery power, because the dataTaker serial interface is not being used to transmit data to a disconnected host. DeTransfer and DeLogger automatically enable the return of data during connection, and disable the return of data during disconnection. During a DeTransfer session, the return of data is managed by the commands /R All channels will return data by default when read, however individual channels can be disabled from returning data by the NR channel option. Using DeTransfer, the channel option BEGIN permanently disables the return of data from the second channel. However data from this channel is still available internally for logging and displaying. If the Return Data Switch is enabled (/R), then data from the first channel (1TK) will be returned. If the Return Data Switch is disabled, then no data is returned. Using DeLogger, return of data from individual channels can be disabled in the
Channel Properties dialog in the Program Builder. Firstly define the channel in the normal way, then right click on the Data Use box for the channel, select the Data Use tab, and check Do NOT return data to host computer. Free Format Mode for Returned DataIn the Free Format Mode, all data is returned from the dataTaker in user definable data item and data block formats. The user formats apply to data returned directly to the host as the input channels are read and calculations exeuted, and to stored data returned from the internal data memory or memory card. The data is returned in ASCII strings as either floating point data or exponential data, with channel identification and units text. In these formats, each digit is an ASCII character (eg. 123.45), which allows returned data to be displayed directly onto a terminal screen for viewing, to be input into a computer for processing, or to be sent directly to a serial printer to produce hardcopy. When the returned data is input to a host computer, it can be written directly into disk storage as an ASCII file. This ASCII file format is compatible with a range of data processing packages such as databases, spreadsheets, statistics packages, graphics packages, word processors, etc. The format of returned data can be changed to suit applications software for particular data processing and presentation tasks. The Free Format Mode also facilitates data transmission to the host either directly via a cable, via public telecommunications networks (PSTN) using modems, via the cellular phone network, or via radio or satellite telemetry systems. Data Item FormatIn Free Format Mode, each item of data produced by the dataTaker is returned to the host computer in a default format. This format is a descriptive or conversational style, and is selected whenever the dataTaker is powered up or reset. However the format of each item of data can be modified to produce a data format suited to particular applications. The numeric format and the description of data items can be changed in a number of ways, and is discussed in the following pages. Data Numeric FormatTwo numeric formats for returned data are available in the Free Format Mode, which can be modified to create a numeric format suited to the host software requirements. The default numeric format is dependent on the magnitude of the data as follows data values within the range of ±10±6, and with fewer than six significant digits, are returned in floating point format. The number of decimal places is set according to the number of significant digits for the channel measurement. data values outside the range of ±10±6, or with more than six significant digits, The data from each channel can also be specified individually to be in floating point or exponential format, with a specified number of significant digits and decimal places. Floating Point Data FormatData within the range of ±10±6, and with fewer than six significant digits, is returned in the floating point format as follows nncc sdddd.ddd uu [delimiter] where nn is the channel number Some examples of data returned in the floating point format follow 3V ñ12.277 mV Whenever the magnitude of data is outside the range of ±10±6, then the dataTaker automatically selects the exponential format (see below). The floating point format can be forced by the FFn channel option, where n is the number of decimal places (0 ñ 6). Using DeTransfer, the command for example 5BGI(FF2) instructs the dataTaker that the strain gauge data is to be returned in Fixed Floating point format with 2 decimal places (FF2). The FFn channel option is also used to fix the number of decimal places in returned data, which may be appropriate to match the resolution of data to the resolution of a sensor. Using DeLogger, the number of decimal places for any channel can be set in the Channel Properties dialog box in the Program Builder.
Exponential Data FormatData values that are outside the range of ±10±6, or have more than six significant digits, are returned in the exponential format as follows nncc sd.dddEsdd uu [delimiter] where nn is the channel number Some examples of data returned in the exponential format follow 2V 1.277E7 Newtons When the magnitude of data is in the range of ±10±6, the dataTaker automatically selects the floating point format (see above). The exponential format can be forced by the FEn channel option, where n is the number of significant digits (0 ñ 6) for the mantissa. Using DeTransfer, the command for example 5BGI(FE2) instructs the dataTaker that the strain gauge data is to be returned in Fixed Exponential format with 2 significant digits in the mantissa (FE2). The FEn channel option is also used to fix the number of significant digits in the mantissa of data returned in exponential for particular channels. It is not appropriate to force Fixed Exponential format in DeLogger, because DeLogger is using the Fixed Format Mode for data (/H). The exponential format for data generally applies to data resulting from user defined sensor calibrations (polynomials and spans) and from calculations. The ranges for basic signal types measured by the dataTaker rarely require the exponential format for basic data. Mixed Data FormatThe dataTaker can be programmed to automatically select between floating point and exponential format for individual channels depending on the magnitude of data. The FMn channel option forces the data format as follows floating point format for data in the range of ±10-4 to ±10+n exponential format for data outside the range of ±10-4 to ±10+n where n also specifies the number of decimal places in the floating point data, or the number of significant digits in the mantissa, respectively. Using DeTransfer, the command for example 5BGI(FM2) instructs the dataTaker that the strain gauge data is to be returned in Fixed Floating point format if the data is in the range of 0.0001 to 100.00,and Fixed Exponential format if data is outside this range (FM2). It is not appropriate to force Mixed format in DeLogger, because DeLogger is using the Fixed Format Mode for data (/H). Global Number of Significant DigitsData returned from the dataTaker normally has 1 to a maximum of 5 significant digits, depending on the magnitude of the data. The maximum number of significant digits in data returned in real time can be globally defined by the Parameter32 command. This sets the maximum number of significant digits, and data with fewer significant digits is not expanded. Using DeTransfer, the command for example P32=2 globally sets a maximum number of 2 significant digits for all data returned in real time. Parameter32 can be defined within the range of 1 to 9. Data stored in the internal memory or memory card is stored to 5 significant digits, irrespective of the setting of the Parameter32 command. It is not appropriate to set the number of significant digits in DeLogger, because DeLogger is using the Fixed Format Mode for data (/H). Setting Significant Digits and Decimal Places for Individual ChannelsSetting the number of decimal places in floating point data, and the number of significant digits in the exponential data, adjusts the output resolution of the data. There are a number of practical benefits in being able to define the resolution of returned data, including matching the error limits of the sensors used, so that data is not returned to degrees of resolution beyond the capability of the sensors improves tabulation of returned data on printers and terminals reducing the number of characters which must be transmitted when data is returned. This is particularly relevant where data is transmitted at lower baud rates via modems, radio links, etc. The dataTaker returns all analog data at the maximum resolution possible for each input type, according to the gain (range) used for signal measurement, the number of significant digits possible for such measurements, and the magnitude of the data. However the maximum resolution is determined purely on the basis of the capabilities of the data logger, and does not take into account the precision of the sensor. Analog data in the range of ±10±6 is returned by the dataTaker in the floating point format, for which the number of decimal places may be defined. Digital data such as logic bit state, logic byte state and counts are returned as integer data, and do not have a fractional component. However the average and standard deviation for digital state and counts is returned as floating point data, and the number of decimal places can be defined. The number of decimal places in returned data can be reduced from the maximum system resolution, but cannot be increased beyond that maximum. The resolution of data returned in exponential format can also be defined, for which the number of significant digits is defined. The number of decimal places for data in floating point format can be defined by the FFn and FMn channel options, and the number of significant digits in exponential format can be defined by the FEn and FMn channel options ( See Section III ñ The Analog Input Channels). Using DeTransfer, the command for example 1V(FF1) 2V(FF3) sets the number of decimal places to 1 for the first channel, and sets the number of decimal places to 3 for the second channel, to match sensor capability. The default setting for the number of decimal places or the number of significant digits is 5, which causes data to be returned at maximum possible resolution as determined by the dataTaker. The maximum number of significant digits can be set by the Parameter32 command in the range of 1 to 9. The FFn, FEn and FMn channel options sets the maximum number of decimal places or significant digits in returned data, not the total number. Therefore if the internal data has fewer decimal places or significant digits than defined, trailing zeros are not added. This is illustrated in the table below
When the number of decimal places for returned data is reduced from that of the maximum internal resolution, the last decimal place is rounded upwards according to the magnitude of the next digit. This is illustrated in the table below
Date and Time FormatsThe date is returned from the real time clock of the dataTaker in the default formats Date DD/MM/YYYY (50 Hz operation) or Date MM/DD/YYYY (60 Hz operation) The default format for date is determined from the mains or line frequency setting on the DIP switch. The time is returned from the real time clock of the dataTaker in the default format Time HH:MM:SS Examples of the date and time returned in the default formats follow Date 20/6/2003 The format for the date and the time can be modified in a number of ways as follows the date can be expressed as the date either in DD/MM/YYYY format, MM/DD/YYYY format, or as the number of days since 01/01/1989 the time can be expressed either in the HH:MM:SS format, as the number of seconds since last midnight, or as decimal hours if the default time format of HH:MM:SS is used, the character separating the hours, minutes and seconds can be specified a decimal day format is also available which combines the day number and time of day in a single value (See System Variable 12) The date and time is returned by including these in a Schedule, and by enabling the Date Switch (/D) and the Time Switch (/T) (See Section III ñ The Real Time Clock). The commands for formatting the day number, date and time returned from the real time clock of the dataTaker are detailed in Section III ñ The Real Time Clock. Note : The date and time of the real time clock must be set in the same format as is defined for the return of date and time. It may be appropriate to change the format for date and time if you are supervising and programming the dataTaker from DeTransfer. However changing the format of date and time is not appropriate if you are using DeLogger. Data Item DescriptionThe default data format returned to by the dataTaker is a descriptive or conversational style, which is suitable for displaying data on a host screen such as with DeTransfer, for printing data, and for passing data to data acquisition software, data processing packages and data presentation packages. The default data format is illustrated by the following examples Date 20/6/2003 Each data item has several descriptors, which identify the data as follows the channel number indicates the source of the data the channel identifier indicates the type of signal or sensor the units text indicates the engineering units for the data each channel can be given a unique name This description of data items is definable in a number of ways, and is described in the following sections. These commands are global, and specify the format for all data returned from the dataTaker. It may be appropriate to change the data item descriptions if you are supervising and programming the dataTaker from DeTransfer. Changing the data item descriptions other than the channel name is not appropriate if you are using DeLogger. Channel NumberThe return of channel numbers is determined by the Channel Number Switch as follows /N Enable return of channel numbers (Default) The Channel Number Switch defaults to /N when the dataTaker is initially powered up, hardware reset or executes a RESET command. If the channel is located on a Channel Expansion Module, or if a dataTaker channel has been addressed as module 0, then the channel number is preceded by the module number. The module number is part of the channel number, and is included if the Channel Number Switch is enabled (/N) and not included if the Channel Number Switch is disabled (/n). Channel IdentifierChannel identifiers are returned from the dataTaker only if the channel numbers are being returned (/N), when the return of channel identifiers with the channel number is determined by the Channel Identifier Switch as follows /C Enable return of channel identifiers (Default) The Channel Identifier Switch defaults to /C when the dataTaker is initially powered up, hardware reset or executes a RESET command. If return of channel numbers is disabled (/n), then return of channel identifiers is also disabled. The examples below illustrate the interactive effect of the Channel Number Switch and Channel Identifier Switch on returned data 5PT385 ñ74.29 Deg C /N/C Channel NameThe default labelling of returned data by the channel number and channel identifier can be replaced by unique channel names. The channel names of up to 16 characters are specified as channel options. Using DeTransfer, the command for example 1TK("Boiler Temp") names the channel in terms of the origin of the data. If a name has been defined for a channel, then this is returned with the data instead of the channel number and channel type. However the return of a defined channel name is disabled by the /c and /n Switch commands. DeLogger also supports naming of channels. Channel names can be entered in the Program Builder by clicking on the sensor icon for a defined channel, and selecting Label to open the Channel Label dialog.
The new channel name is then used throughout DeLogger to identify this particular data source. Units TextThe return of units text is optional, and is determined by the Units Text Switch as follows /UEnable return of units text (Default) The Units Text Switch defaults to /U when the dataTaker is initially powered up, hardware reset or executes a RESET command. Date or Day and Time LabelsThe return of the Date or Day label and the Time label is determined by the Channel Number Switch, and return of the units of time is determined by the Units Text Switch, as follows /N Enable return of Date or Day and Time labels (Default) The return of time units is only appropriate to the time formats of seconds since midnight and decimal hours (See Section III ñ The Real Time Clock). Data Delimiter CharacterEach item of the data, the date or day, and the time, can be delimited by a user definable data delimiting character. If the Units Text Switch is enabled (/U), then each data item will be delimited by the CR/LF pair. If the data is being returned to a terminal screen such as DeTransfer or to a printer, then each data item will be written on a new line. However if the Units Text Switch is disabled (/u), then data items are delimited by the character defined by the Parameter22 command. The delimiter character is defined as the ASCII decimal code for the required character. Using DeTransfer, the command for example P22=44 defines the data item delimiter to be the comma character (ASCII 44). The default definition for Parameter22 is CR (ASCII 13) when units text is enabled, and SPACE (ASCII 32) when units text is disabled. Whenever Parameter22 is defined as a CR, then a LF is automatically appended to produce a CR/LF new line sequence. It is not appropriate to set the data delimiter from DeLogger. Fixed Field WidthEach item of data returned to the host computer can have a fixed field width capacity, which can be set between 1 and 80 characters. By default each item of data returned is in variable width, which is dependent on the magnitude of the data. The setting of Parameter33 allows for fixing the number of characters returned with each data item. The benefits of fixing the field width for data are as follows producing tabular data to aid in the clarity of the data returned providing a consistent number of characters for each data item, which assists import of data into some third party software packages. The following example illustrates data returned without fixed field width applied 18.8 18.7 3.498 0.000 If a fixed field width of 8 characters is set by the command from DeTransfer P33=8 then the returned data is more tabular as follows 18.8 18.7 3.498 0.000 Each data item is right justified and space padded. If the name or value is larger than the field width specified by the Parameter33 setting, then the name or value is truncated from the right. The $ string channel, Alarm text messages, Test results and Status reports are not effected by the setting of Parameter33. It is not appropriate to set the data field width in DeLogger. Some Examples of Data Item FormatsThe default data item format for returned data is defined by the following commands, which could be entered from DeTransfer /U /N /C P22=13 Data is returned in a descriptive format, and can be read directly from the DeTransfer screen or printout from a printer. These default settings are automatically selected when the dataTaker is initially powered up, is reset, or executes a RESET command. The default data item format is illustrated in the following examples Date 12/06/2003 Many combinations of settings for the data formatting Switches, the data delimiter character, and the data resolution are possible to change the data item format. Using DeTransfer, the most common alternative is /u /n /c P22=44 which returns data in a format suitable for reading directly by host software, as illustrated below 12/06/1992,11:30:00,12.279,ñ74.2,87.36,1,2391 The default data item format can require transmission of up to 20 characters for each data item returned to the host. During real time data acquisition the default data item format may reduce maximum sampling rate, particularly if the communications baud rate is low. This is because the logger will not run a Schedule until all data from the previous running of the Schedule has been sent to the host. Disabling the channel number, channel identifier and units text, and reducing the number of decimal places, will reduce each item of data to between 2 ñ 7 characters depending on the data type. Data Block FormatThe data resulting from reading more than one input channel or performing more than one calculation is returned by the dataTaker in a block format, which comprises a grouping of the individual channel data. The format of each data item in the block is user definable, and is described above in Section III ñ Data Item Format. The format of the data block is the same for real time data, and data from the internal memory and memory card. Data returned from memory can optionally include an end of stored data character. The date and/or time of the readings may be included at the start of each data block, depending on the setting of the Date Switch and the Time Switch (See Section III ñ The Real Time Clock). Each data block can optionally be preceded by the address of the dataTaker returning the data. This allows blocks of data being returned from a network to be identified. Formatting the data block is often appropriate if you are using DeTransfer to supervise the dataTaker, however is not appropriate if you are using DeLogger. Data Block Format for Real Time DataThe default data block format for data returned directly to the host in real time as input channels are read and calculations performed is illustrated below Date dd/mm/yyyy Date The format of each data item in the block is definable, as described above in Section III ñ Data Item Format. Each block of data resulting from successive reading of input channels and evaluation of calculations is delimited by a user definable Schedule or block delimiter character. If the Units Text Switch is enabled (/U), then successive blocks of data are delimited by CR/LF. If returned data is displayed or printed, then successive blocks of data are separated by a blank line. If the Units Text Switch is disabled (/u), then successive blocks of data are delimited by the character defined via the Parameter24 command. The delimiter character is defined as the ASCII decimal code for the required character. Using DeTransfer, the command for example P24=44 defines the block delimiter to be the comma character (ASCII 44). The default definition for Parameter24 is CR (ASCII 13). Whenever Parameter24 is defined as a CR, then a LF is automatically appended to produce a CR/LF new line sequence. Data Block Format for Stored DataThe default data block format for data returned to from the data memory or a memory card is the same as that returned in real time, with an additional character after the last data block is returned to signify the end of stored data. The end of stored data character is defined by the Parameter25 command, as the ASCII decimal code for the required character. Using DeTransfer, the command for example P25=42 defines the end of stored data character as an asterisk (ASCII 42). The default is Parameter25=0 (NULL), and no character is returned. Examples of Data Block FormatsThe default data block format for data returned in real time, or from the data memory, is defined by the following commands /U /N /C /t /d P22=13 P24=13 returns data in a format that can be read directly from a terminal screen or printer. These default settings are automatically selected when the dataTaker is powered up, is reset, or executes a RESET command. The default data block format is illustrated in the following example Date 23/06/2003 Many combinations of settings for the Switches and Parameters are possible to define the data block format. The most common setting is /u /n /c /m /e /T /D P22=44 P24=13 which returns data in a Comma Separated Variable (csv) format suitable for importing directly into analysis software such as Microsoft Excel, as illustrated below 23/06/2003,15:31:15,-12.27,2391,162.2 The length of each block of data is determined by the number of channels read and/or calculations executed. Where two or more groups of channels are read by different Schedules, then whenever two or more of the Schedule times coincide the data is returned in separate blocks for each Schedule. If the Units Text Switch is enabled (/U) the data blocks are delimited by CR/LF. If the Units Text Switch is disabled (/u) the data blocks are then delimited by the character defined at Parameter24. The last block of data from the data memory or memory card will be terminated by the end of stored data character if one is defined in Parameter25. This is illustrated in the following example Date 23/06/2003 and 23/06/2003,15:31:15,-12.27,2391,162.2 where Parameter25 is set to ASCII 42 (asterisk). dataTaker AddressEach data block can be preceded by the address of the dataTaker returning the data. This allows blocks of data being returned from a network to be identified. The return of the dataTaker address is optional, and is determined by the Logger Address Switch as follows /L Enable return of logger address The Logger Address Switch defaults to /l when the dataTaker is initially powered up, hardware reset or executes a RESET command. If the return of logger address is enabled, then the data block will be similar to the following examples Logger 1 and 1,11:45:00,-12.15,2267,159.8 Enabling the logger address is not appropriate in DeLogger. |
Page ContentSection 1Construction of the dataTaker 50 Construction of the dataTaker 500 600
Section 2Powering Sensors from the dataTaker The RS232 COMMS Serial Interface Measuring 4-20mA Current Loops Measuring Frequency and Period 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 Installing The Panel Mount Display
Section 3Communication Protocols and Commands Entering Commands and Programs |
