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

Commands to supervise and program the dataTaker are entered into the logger by any of four basic methods

the most common method is to enter commands into the dataTaker directly from the host computer software, via the RS232 COMMS serial interface

commands can be recorded into a memory card, and automatically read into the dataTaker when the memory card is inserted into the card socket of the logger

commands can be entered into a dataTaker 500 or dataTaker600 series logger via the NETWORK interface. The commands are transmitted from a host computer that is connected to the RS232 COMM interface of another logger in the network, then via the network to the target dataTaker on the network.

Note :  The dataTaker 50 does not support networking.

commands can be conditionally initiated internally from alarms, as a result of alarm conditions becoming true

The command buffer within the dataTaker will accept up to 250 characters. This limits single command lines to a maximum length of 250 characters.

Entering Commands in the Low Power Mode

The dataTaker usually operates in normal power mode, waiting for the next Schedule to be triggered to collect and process data, or for commands to be received into the RS232 COMMS serial interface.

When the dataTaker is in the low power mode, various sections of the logger, including the microprocessor and serial interface circuitry, are powered off. When a Schedule triggers, or command characters are received into the RS232 COMMS serial interface, then the dataTaker 'wakes up' to the normal power mode and performs the necessary functions.

However if commands are sent to the dataTaker while in the low power mode, then a number of the leading characters of the command will be missed as the logger wakes up. The dataTaker takes approximately 250 mS to wake up to normal mode, and so any characters received during this period will be missed. The number of characters missed depends on the communications baud rate, and at the higher baud rates entire commands may be missed.

Missed characters will result in command syntax errors due to incomplete commands being received. The dataTaker will return error messages for what would appear to be syntactically correct commands.

if the dataTaker is being commanded manually from a terminal host, then character loss is less of a problem because typing speed determines character rate. Generally only the first character or two will be missed. Loss of characters during the wake delay can be overcome by sending several CR/LF characters to wake the logger by tapping the Enter key, before entering command characters.

if the dataTaker is commanded from dedicated host software, the degree of character loss is determined by the baud rate

DeTransfer and DeLogger both provide for this wake up delay by sending a linefeed character to the dataTaker, and waiting for 250 mS before sending the command. A similar practice should be adopted for all host software used to supervise the dataTaker.

After the dataTaker wakes from low power mode by characters received into the RS232 COMMS serial interface, the logger remains in the normal power mode for 30 seconds after the last character is received, before dropping to the low power mode again.

In applications where low power mode is not required, such as when an adequate power supply is available, then the automatic low power mode can be disabled by the Parameter15=2 command (See Section II - Powering the dataTaker). This command can also be used to keep the logger awake during a programming session, and the logger then returned to the automatic low power mode by the Parameter15=0 command after programming.

The automatic low power mode is disabled whenever the dataTaker is powered from external power supplies.

Entering Commands from a Memory Card

The memory card has an area of memory reserved for storage of dataTaker commands. This is referred to as the program area, and can contain commands totalling up to 4090 characters.

Whenever a memory card is inserted into the dataTaker, the logger firstly checks if any commands stored in the program area of the card. If there are commands stored in the program area of the memory card, then these are read into the command buffer of the dataTaker and are executed.

If there are no commands stored in the program area of the memory card, then the dataTaker continues the current task.

Any of the dataTaker commands can be stored in the program area of the memory card.

The methods for recording commands into the memory card, and use of the memory card for programming the dataTaker, are discussed in Section III - Programming the dataTaker from the Memory Card.

Entering Commands from the Network - dataTaker 500/600 loggers

Commands can be entered into any of the dataTaker 500/600 series loggers within a dataTaker local area network, via the network.

The host computer is connected to the RS232 COMMS interface of any logger within the network. commands addressed for any other dataTaker 500/600 series logger within the network are sent out of the NETWORK interface of host logger, and received into the NETWORK interface of the target logger.

The direction of commands to different dataTaker 500/600 series loggers within the network requires that commands be prefixed by an address, which matches the address of the target logger.

The commanding of dataTaker 500/600 series loggers in a network is discussed in detail in Section III - Networking the dataTaker 500/600 Series Loggers.

General Rules for Entering Commands

There are a number general rules for entering commands into the dataTaker, which apply to all methods of command entry. The rules apply when entering commands from DeTransfer, however do not apply when using DeLogger since DeLogger is interacting with the logger rather than the user.

These rules provide for simplicity and flexibility when entering commands, while providing syntax, which is easy to use.

Command Line Editing

The dataTaker supports several line-editing functions during entry of commands. These line editing functions particularly apply to the situation where the dataTaker is being supervised either from a terminal, or from a computer running either a general communications program or terminal emulation program.

Backspace [BS]

Sending a backspace character (ASCII 8) to the dataTaker will cause the last character transmitted by the host to be erased from the internal command buffer of the logger.

If communications echo is enabled by the Echo Switch /E, then the dataTaker responds with a 'backspace  space  backspace' character sequence, which has the effect of deleting the last character from the command line on the terminal screen.

Repeated backspaces will erase successive characters from the command line, and will eventually erase the entire command.

Delete [DEL]

Sending a delete character (ASCII 127) to the dataTaker causes a partially or wholly entered command to be aborted. However the delete character must be sent before the carriage return, which terminates the command.

If communications echo is enabled by the Echo Switch /E, then the dataTaker responds with the characters  <<  followed by a carriage return and line feed (CR/LF), which indicates on a terminal screen that the command has been aborted.

Carriage Return [CR]

Terminates a command line, and instructs the dataTaker to process the command and execute the commanded functions.

If communications echo is enabled by the Echo Switch /E then the dataTaker responds with a CR/LF sequence to the host.

Line Feed [LF]

The line feed character (ASCII 10) is ignored.

Tab and Space Characters

The Tab (ASCII 9) and Space (ASCII 32) characters can both be used to insert a space character. The Tab or Space character is the delimiter character between the elements of a complete command.

If communications echo is enabled by the Echo Switch /E, then the Tab and Space characters are echoed as a space character.

Command Separators

Space or tab characters are used within the command lines to separate the various command components, according to the following rules

there must be at least one separator between the command address, command type and individual items in a schedule list as follows

#1  R10M  1..10V  1..2DSO=0  3..4DS
  ^     ^       ^          ^

STATUS3  TEST
       ^     ^

   Omission of separators from between the command components will cause the
   remainder of the command to be aborted.

separators are not permitted within the command address, the command type, or individual items in a schedule list as follows

#  1  R  A  10  M   1  ..  10  V  1 ..2  DS0 = 0
 ^     ^  ^   ^      ^   ^   ^     ^   ^    ^ ^

STATUS  3
      ^

Inclusion of separators within the command components will cause the
   remainder of the command to be aborted.

Self Documentation of Commands

With the exception of the Switch commands (See Section III - Switch Commands), all dataTaker command characters and channel type identifier characters are strictly upper case characters (capitals).

Commands may be made self-documenting by completing the name for each command or identifier in lower case as follows

Repeat10Min Day Time 1..5Volt /Retn to host

When the command is read by the dataTaker, all of the lower case characters are ignored and only the upper case characters are retained in the command.

The lower case characters are removed from the command line as the line is entered, and therefore do not consume space in the internal command buffer.

Therefore the above command example would reduce to

R10M  D  T  1..5V  /R

in the dataTaker command buffer.

Self-documentation of commands can be further improved by using the underscore character to separate word combinations

Repeat_10_Min Day Time 1..6Thermocouple_T

Self-documentation may also be used in the Switch commands (See Section III - Switch Commands). However the case of the first command character following the / character must be maintained appropriate to the setting required (upper case to enable the switch, and lower case to disable the switch) as follows

/Return_data  /messages_off  /echo_off

/return_no_data  /Messages_on  /Echo_on

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