Instructions

UM-0085-B09 DT80 Range User Manual Page 44
RG
Channel Option Table
Category
Channel
Option
Mutual
Excl
Function
Range of
Option (n)
Comment
Input
Termination
(DT80/
81 Series
1 only)
T
Terminate +, – inputs with 1MΩ
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
Unterminate +, – 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
ESn
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
MDn
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.