Channels view parameters (input devices)

The
Channels
view for the HART input device includes these parameters:
TIP:
These parameters are not available in Run mode. The available parameters vary depending on the devices.
Parameter
Description
Channel
Displays the channel number to which this configuration applies.
Input Type
Displays the input type of the device.
Input Range
Determines the operating range and signal type. Valid values are:
  • -10 V to 10 V
  • 0 V to 5 V
  • 0 V to 10 V
  • 0 mA to 20 mA
  • 4 mA to 20 mA
     (default)
To use HART field devices, select
4 mA to 20 mA
.
Not configurable when in Run mode.
Enable HART
Indicates HART communication is enabled on the channel. Enable HART for any channel that has a HART device connected to it to display information in the
HART Device Information
 view.
Clear the checkbox to disable HART communication. When HART communication is disabled:
  • HART messages are not sent on the channel.
  • HART pass-through messages are not sent.
  • HART data for this channel is not updated in the input tag.
Enable HART
 is not configurable when:
  • In Run mode
  • Input Range
     for input devices is not set to
    0 mA to 20 mA
     or
    4 mA to 20 mA
  • Output Range
     for output devices is not set to
    0 mA to 20 mA
     or
    4 mA to 20 mA
High Signal
Defines the maximum signal produced by the channel.
This value must be greater than the
Low Signal
 value.
Default is 20.0000.
Not configurable when in Run mode.
Low Signal
Defines the lowest signal produced by the channel.
This value must be less than the
High Signal
 value.
Default is 4.0000.
Not configurable when in Run mode.
Units (Signal)
Shows the unit of measurement for
High Signal
 and
Low Signal
.
High Engineering
Indicates the engineering units that corresponds with a signal value equal to the
High Signal
. For example, suppose you have a temperature transmitter that produces 20 mA current at 750 °C. The
High Engineering
 value in this case would be 750.
This value cannot be equal to the
Low Engineering
 value.
Valid values are in the range of -10000000...100000000 (float). Default is 100.0000.
It is recommended to set the
High Engineering
 value to correspond to the device
Upper Range
 value so that the device and module use the same engineering units. When online, this value is displayed in the
HART Device Information
 view.
Not configurable when in Run mode.
Low Engineering
Indicates the engineering units that corresponds with the signal value equal to the
Low Signal
. For example, suppose you have a temperature transmitter that produces 4 mA current at -180 °C. The
Low Engineering
 value in this case would be -180.
This value cannot be equal to the
High Engineering
 value.
Valid values are in the range of -10000000...100000000 (float). Default is 0.0000.
It is recommended to set the
Low Engineering
 value to the device
Lower Range Value
 so that the device and module use the same engineering units. When online, this value is displayed in the
HART Device Information
 view.
Not configurable when in Run mode.
Units (Engineering)
Shows the unit of measurement for
High Engineering
 and
Low Engineering
 and for the channel’s input value.
Digital Filter
A filter time constant value from 0...20100 milliseconds. The default is 0.
This is a first order lag filter that smooths input transitions. (It is called a digital filter because it is done in the software by the device, not by a hardware filter).
A value of 0 turns the Digital Filter off. Measured changes in the signal value pass immediately to the controller.
Not configurable when in Run mode.
Disable Alarms
Determines whether process alarms are generated.
  • If selected, the device does not generate process alarms.
  • If cleared, the device generates process alarms.
Real Time Sample (RTS)
Interval of time (in milliseconds) that controls how often the device's inputs are to be sampled.
Applies to all channels on the device.
The RTS period controls how often the device prepares new readings. The Requested Packet Interval (
RPI
in the
Connection
 view) controls how often the device sends its current readings to the controller. These two values should be similar so that each reading gets sent to the controller one time.
The valid range for RTS varies depending on the setting for
Device filter
.
Not configurable when in Run mode.
Device filter
Specifies the frequency used to filter out the line noise. This filter attenuates the selected frequency and its harmonics in the input signal.
Applies to all channels on the device.
Valid values are:
  • 10 Hz
  • 15 Hz
  • 20 Hz
  • 50 Hz
  • 60 Hz
     (default)
  • 100 Hz
  • 250 Hz
  • 1000 Hz
     (not allowed on HART enable channels)
Not configurable when in Run mode.
Keep HART Replies for
Specifies the length of time that HART replies that are received from the Field Device in response to Pass-through messages are kept. You must retrieve them within this time or the device discards them.
Valid values are from 1 through 255 seconds. Default is 15.
Applies to all channels on the device.
Not configurable when in Run mode.
Pass through
Indicates how often pass-through messages occur. The valid values are:
  • Once per two channels scanned
     - A pass-through message is sent (if one is pending), after 2 channels have PVs scanned to the input tag.
  • Once per module scan
     - Select if you want to minimize the impact pass-through clients have on reading the PVs into the input tag.
  • Once per channel scan
     - A pass-through message is sent (if one is pending), after each channel has its PVs scanned to the input tag.
Select from the list to give pass-through clients, such as FactoryTalk Asset Centre, higher priority than reading PV, SV, TV, FV and field device health into the input tag.
Not configurable when in Run mode.
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