UM-0085-B09
DT80 Range User Manual
Page 44
RG
Channel Option Table
Category
Channel
Option
M
ut
ua
l
E
xcl
Function
Range of
Option (n)
Comment
Input
Termination
(DT80/ 81 Series
1 only)
T
Ter, – inputs with 1M
Ω
to
AGND
terminal
Provides input bias current path to ground to
prevent inputs "floating" – particularly when
independent (differential) inputs are used.
Not required on DT80 Series 2 or DT85 as a
ground path is always present.
U
default
Unter, – inputs
Input
Attenuators
A
Enable1 ÷10 (
1 ÷16 Series 4
)
input attenuators
Attenuators default ON for
HV
,
AS
channel
types, OFF for other types.
NA
default
Disable input attenuators
Resistance and
Bridge
2W
2-wire measurement
Specifies the number of wires run between
the
DT80
and the resistance or bridge. More
wires generally mean better accuracy.
3W
default
3-wire measurement
4W
4-wire measurement
Gain lock
(none)
default
Auto-range over 3 gain ranges
Selects between 3V, 300mV, 30mV ranges if
input attenuators disabled
Selects between 30V, 3V, 300mV ranges if
input attenuators enabled
GL50V
Lock channel gain for
±50V input signal range
(Series
4 only)
Valid only if input attenuators are enabled
GL30V
Lock channel gain for
±30V input signal range
Valid only if input attenuators are enabled
GL3V
Lock channel gain for
±3V input signal range
GL300MV
Lock channel gain for ±300mV
input signal range
GL30MV
Lock channel gain for ±30mV
input signal range
Valid only if input attenuators are disabled
Excitation
I
Supply 200µA current excitation
on * terminal
Precision current source. Low excitation
current minimises self-heating in resistive
temperature sensors and allows high
resistances to be measured.
II
Supply 2.5mA current excitation
on * terminal
Precision current source. Higher excitation
current allows more accurate measurement
of low resistances (< 700Ω).
III
Supply 2µA current excitation on
* terminal
Precision current source. Low excitation
current minimises self-heating in resistive
temperature sensors and allows high
resistances measurements.
V
Supply approx. 4.5V voltage
excitation on * terminal
Voltage source is not regulated
E
Connect external excitation
source (
EXT *
terminal
)
to
channel's * terminal
N
default
No excitation by
DT80
(assumes
externally applied excitation)
Excite terminal (*) may be used as a shared-
terminal input channel
Channel Factor
value
Linearise/scale the measured
value
depends on
chan type
A scale factor or other parameter specific to
channel type (see the channel factor column
in
Table 3: DT80 Channel Types(P37)
)
Reference Offset
2V
Measure relative to 2.5V rather
than 0V
Used with
F
channel type to set threshold to
+2.5V (suitable for TTL level input signals)
rather than the default of 0V.
Extra Samples
ES
n
default = 0
Perform
n
additional samples
and average them
0 to 30000
Can reduce noise. Total measurement time is
n
+1 mains periods. Analog channel types
only.
Measurement
Delay
MD
n
default = 10
After selecting channel, delay for
n
ms before starting
measurement
0 to 30000
Specifies the settling time required before a
sensor can be measured. Default is 350ms
for
FW
channel. Analog channel types only.
Low Threshold
LT
Set low input voltage thresholds
for high speed counters
Valid for
1HSC
,
2HSC
(DT80/81/85) and
1PE
(not DT81) channels.