The Digital Output Channels

The dataTaker 50 has 5 bi-directional TTL/CMOS compatible digital channels, which can be used for digital inputs or digital outputs.

The dataTaker 500/600 series of data loggers have 4 bi-directional TTL/CMOS compatible digital channels, which can be used for digital inputs or digital outputs.

As digital output channels, these are implemented as open collector CMOS/TTL compatible logic outputs.

The Channel Expansion Module has 10 digital output channels, of which 5 are implemented as open collector CMOS/TTL compatible logic outputs, and 5 are implemented as single pole relays.

These open collector output channels are active low, in that they switch low to ground when turned ON. This allows the connection of low voltage relays directly between a supply voltage and the output channel terminal.

An optional delay period can be invoked after switching the digital outputs, which pauses the dataTaker for a period before proceeding with execution of the dataTaker program. During the delay period only time keeping, counting and servicing of the serial interfaces is maintained.

An optional reset can be specified when switching digital outputs, to reset the digital outputs to the opposite state to that selected thereby producing a pulse output.

Digital Output Types

There are several digital output type identifiers, depending on the type of channel and whether the channels are used for bit or byte outputs. These are detailed in the table below

Digital Output Types
		Number of Output Channels
Output Signal	Output Type Identifier	DT50	DT500 DT600	CEM
Digital Bit Output	DSO	5	4	10
Digital Byte Output	DBO(mask)	see below
Warning Outputs	WARN	5 if have a display	5 if have a display	0

Switching the Digital Bit Outputs

The digital bit output channels are switched ON by assigning any positive or negative value to the channel, and are switched OFF by assigning a 0 to the channel.

An optional delay period can be invoked after switching the digital outputs, which pauses the dataTaker to allow external conditions to settle before proceeding with execution of the dataTaker program. The delay can be from 1 to 65535 mS.

An optional reset can be specified when switching digital outputs, to reset the digital output to the opposite state to that selected thereby producing a pulse output. If a delay period is specified, then the output is reset after the delay.

The digital bit output channels are switched by commands in the general formats

nDSO(delay,R)=state

and

n..mDSO(delay,R)=state

where

n                 is a single digital output channel
n..m             is a sequence of digital output channels
DSO            is the digital bit output channel identifier
delay           is an optional delay period in millisecs after switching
R                 optional reset to opposite state after switching
state             indicates the state to which the output is set

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

The optional delay period is specified as an integer within the range of 1 to 65535 mS (a little more than 1 minute). If there is no delay period specified, the digital output is switched and the dataTaker continues without delay.

If the reset option is not specified, then the digital output remains in the state to which it is switched.

The state can be specified as a constant, a channel variable or an expression. If the value for state is a decimal value, then the value is rounded to the nearest integer.

A state value of 0 will turn the output OFF, while any value other than 0 will turn the output ON.

Using DeTransfer, digital output channels can be switched by commands for example

1DSO=1
2DSO=(5CV/3)
1..4DSO=0
1:2..5DSO=1

which

turns digital output channel 1 of the dataTaker ON

turns digital output channel 4 of the dataTaker ON (assuming the expression does not evaluate to zero)

turns digital output channels 1 through 4 of the dataTaker OFF

turns digital output channels 2 through 5 of Channel Expansion Module ON

Using DeLogger, digital output channels can be directly switched in the program created in the Program Builder as follows

The ON state is indicated by a green traffic light, and the OFF state is indicated by a red traffic light.

However this method does not support assigning expressions to the digital output channels. Expressions can only be assigned by using the User channel in the Program Builder (DeLogger ver 4.2.16 or later) as follows

Delay Period and Reset

The optional delay period pauses the dataTaker before proceeding with execution of the dataTaker program. During the delay period only time keeping, counting and servicing of the serial interfaces is maintained.

However if the delay period is used when dataTaker networks are implemented, then delay periods of greater than 1000mS will slow communications over the network. Similarly long delay periods will slow response by the dataTaker when being polled for data by the host.

The reset channel option R resets the digital outputs to the opposite state to that selected, thereby producing a pulse output.

If a delay period is not specified, then the digital output is toggled quickly, producing a pulse width of 10
– 100mS. If however a delay period is specified, then the output is reset after the delay period producing a longer pulse.

The delay period and reset option have limited application when switching the digital outputs directly from commands, but have considerable application when switching digital outputs from within Schedules (See Section III ñ Switching Digital Outputs in Schedules).

Using DeTransfer, the digital output channels can be switched with delays and reset by commands for example

4DSO(1000)=1

which turns digital output channel 4 of the dataTaker ON, and then pauses the program for 1000mS (1 sec) before continuing

2DSO(7500,R)=1

which turns digital output channel 2 of the dataTaker ON, pauses the program for 7.5 seconds, and then resets the output OFF

1:8DSO(5000,R)=0

which turns digital output channel 8 of Channel Expansion Module 1 OFF, pauses the program for 5 seconds, and then resets the output ON

3DSO(0,R)=1
3DSO(R)=1

which both turn digital output channel 3 of the dataTaker ON, and then immediately turns it OFF again.

The delay period and reset are not directly supported by DeLogger, however these can be entered into programs by using the User channel in the Program Builder (DeLogger ver 4.2.16 or later) as follows

Switching the Digital Byte Output

The dataTaker is also able to switch the digital output channels as byte outputs. Digital byte outputs are implemented as groups of successive digital bit output channels.

The digital byte output command can be used to switch groups of digital output channels simultaneously, producing a bit pattern.

Digital bytes are switched beginning at a specified digital output channel number, for the next 8 successive digital outputs. If there are fewer than 8 digital outputs beyond the first digital output channel (as is the case for the dataTaker, but not for the Channel Expansion Module), then the byte is switched only for those output channels that are present.

The digital byte output is specified in a channel list by the identifier

nDBO(mask)=pattern

where

n                 is the first channel to begin switching the byte
DBO            is the digital byte output identifier
mask            is an optional bit mask of which bit channels are to
                   be included in the byte, beginning from n
pattern          is the decimal value of the bit pattern required

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

The pattern can be specified as a constant, a channel variable or an expression. If the pattern is a decimal value, then the value is rounded to the nearest integer.

The optional mask allows individual digital output channels within the group to be enabled, as specified by the bits, which are set in the mask. Channels associated with bits, which are not set in the mask, are not enabled and so are not switched.

If a byte mask is not specified, then the mask defaults to decimal 255 (11111111) and all channels from the nominated first channel are switched.

The delay and reset options for digital bit outputs are not supported for digital byte outputs.

Using DeTransfer, the digital byte output can be switched by commands for example

1DBO=13

which turns digital output channels 1, 3 and 4 of the dataTaker ON, and turns digital output channel 2 OFF. Decimal 13 has the bit pattern of 1011.

5CV=11
2DBO=5CV

which turns digital output channels 2, 3 and 5 of the dataTaker ON, and turns digital output channel 4 OFF. Digital output channel 1 is not addressed.

1:1DBO(85)=255

which turns the digital output channels 1, 3, 5 and 7 of the Channel Expansion Module ON. Digital output channels 2, 4, 6 and 8 are not enabled by the mask, and so are not switched.

The digital byte output channels are not directly supported by DeLogger, however can be entered into programs by using the User channel in the Program Builder (DeLogger ver 4.2.16 or later) as follows

Switching Digital Outputs in Schedules

The digital bit and byte outputs can be made to change state at the start of a program, and at intervals during execution of a program, by placing the commands in Immediate and Triggered Schedules.

The delay period and reset operate in the same manner as for direct digital output commands. During the delay period all analog to digital conversion is suspended.

Switching of digital outputs in this manner allows them to be used to generate pulse trains, control relays which switch power to sensors only when the sensors are to be read, etc.

Digital bit or byte output channels are programmed to be switched in Schedules simply by including the digital output commands in the schedule lists.

Using DeTransfer, digital output channels can be pulsed by the commands for example

BEGIN
RA10M
1DSO(5000)=1 1DSO=0
END

which will turn digital output channel 1 ON for 5 seconds, then turns it OFF, every 10 minutes.

The switching can be completed either by turning the digital output channel OFF again with no delay, or by specifying the reset option as follows

BEGIN
RA10M
1DSO(5000,R)=1
END

The Schedule Triggered by Poll can be used to switch digital output channels from the host computer. For example the command from DeTransfer

BEGIN
RX
3DSO(5500,R)=1
END

will turn digital output channel 3 ON for 5.5 seconds then OFF again whenever a Poll Trigger X is received from the host.

Applications

Switching digital output channels in Schedules has a variety of uses, as the following examples illustrate

BEGIN
RA2S
1DS0(1000,R)=1
END

produces a pulse train from digital output channel 1, that is ON for 1 second, and OFF for 1 second.

BEGIN
RA20M
4DSO(1000)=1
1..3V
4DSO=0
END

digital output channel 4 is controlling a relay, which is switching power to a group of sensors. Every 20 minutes the sensors are powered up, the system waits 1 second while the sensors settle, the sensors are read, and the sensor power supply is turned off again.

These actions can also be programmed from DeLogger as follows

Counting Digital Output Switching

Changes of state of digital output channels in response to switching commands can be counted by the low speed counters associated with each of the digital channels. Each low speed counter is incremented each time the respective output is switched ON.

WARN Channels

The dataTaker 600 series loggers and the Panel Mount Display have a special form of digital output channels called the warning channels. These warning channels control the 3 LEDs on the display, the display backlight, and the beeper in the display.

There are 6 WARN channels, which are allocated as follows

1WARN      Display panel LED 1
2WARN      Display panel LED 2
3WARN      Display panel LED 3
4WARN      Beeper
5WARN      Flash display backlight at approx 1Hz
6WARN      Turn display backlight on and off

Switching the WARN Channels

The WARN channels are switched ON by assigning any positive or negative value to the channel, and are switched OFF by assigning a 0 to the channel.

An optional delay period can be invoked after switching the WARN channels, which pauses program execution. The delay can be from 1 to 65535 mS.

An optional reset can be specified when switching WARN channels, to reset the WARN channel to the opposite state to that selected. If a delay period is specified, then the WARN channel is reset after the delay.

The WARN channels are switched by commands in the general formats

nWARN(delay,R)=state

and

n..mWARN(delay,R)=state

where

n                 is a single WARN channel
n..m             is a sequence of WARN channels
WARN         is the WARN channel identifier
delay           is an optional delay period in millisecs after switching,
R                 optional reset to opposite state after switching
state             indicates the state to which the WARN channel is set

The optional delay period is specified as an integer within the range of 1 to 65535 mS (a little more than 1 minute). If no delay period is specified, the WARN channel is switched and program execution continues immediately.

If the reset option is not specified, then the WARN channel remains in the state to which it is switched.

The state can be specified as a constant, a channel variable or an expression. If the value for state is a decimal value, then the value is rounded to the nearest integer.

A state value of 0 will turn the WARN channel OFF, while any value other than 0 will turn the WARN channel ON.

Using DeTransfer, the WARN channels can be switched by commands for example

1WARN=1
2..3WARN=5CV/3
4WARN(2000,R)=1
5WARN=1

which

turns LED 1 of the display panel ON

turns LED 2 and LED 3 of the display panel ON (assuming that the expression does not evaluate to zero)

turns the beeper ON for 2 seconds, then turns it OFF

flashes the display backlight

Applications

The WARN channels are used to visibly or audibly annunciate alarm commands, internal system states, program states, etc.

The following examples using DeTransfer illustrate some uses for the WARN channels

ALARM3(2TK>110)1WARN

turns LED 1 of the display panel ON when the temperature is greater than 110°C, otherwise holds the LED OFF (See Section III ñ Alarms).

BEGIN
RA1S
3WARN(500,R)=1
END

flashes LED 3 of the display panel at approximately 1Hz

BEGIN
R5M
1V(=1CV)
4WARN=(1CV<1000)
END

turns the beeper on if the measured voltage signal falls below 1 Volt.

The WARN channels are not directly supported in the Program Builder of DeLogger, however these channels can be included in programs by using the User channel (requires DeLogger Ver 4.2.16 or later).