Instructions

UM-0085-B09 DT80 Range User Manual Page 318
RG
Channel Type
R (Ω) at 25°C
YSI Thermistor
Max. Temp °C
Min. Temp °C (without Rp)
YS05
3kΩ
45005, 46005, 46030, 46040
200
44903
90
44904
70
YS07
5kΩ
44007, 44107
150
10
44034 75
45007, 46007, 46034, 46044
250
44905
90
44906
70
YS17
6kΩ
44017, 44117
150
15
45017
250
46017, 46037, 46047
200
YS16
10kΩ
44016, 44116
150
25
44036
75
46036
200
YS06
10kΩ
44006, 44106 150
25
44031
75
45006
250
46006, 46031, 46041
200
44907
90
44908 70
Channel Options
The following channel options are useful with thermistors (YSnn channel type):
•
3W, 4W can be used to select the wiring configuration, as with any resistance measurement
•
I, II,III can be used to set the excitation. For thermistors the I (200µA) option should normally be used, to
minimise any self-heating effects which may occur with higher excitation currents.
• the channel factor is the value of an optional parallel resistor, Rp, which can be used to extend the
temperature range, as described below.
Reading Low Temperatures with Thermistors
Most thermistors increase in resistance as the measured temperature decreases (i.e. they have a negative temperature
coefficient). They tend to be quite non linear and increase in resistance rapidly as the temperature falls into the lower part
of the sensing range.

Series 3 or older
Series 3 or older has an upper limit of 10kΩ for resistance measurement which can limit the usable sensing range of
thermistors. To overcome this you can use a parallel resistor to scale the output of the thermistor back into the
measurement range of the logger, as described in R6 – High Resistance Input with Parallel Resistor (P160).
For
YSnn thermistors, the value of the parallel resistor can be specified as the channel factor and the DT80 will
automatically scale the measured value appropriately. For example, a
YS06 thermistor has a resistance of
approximately 80kΩ at –20°C, so to measure down to this temperature a parallel resistor of about 10kΩ would be
suitable. You would then read the channel using
1YS06(10000)
i.e. the channel factor indicates that a 10kΩ parallel resistor is being used.
If a custom thermistor scaling function is being used then the correction will need to be done using channel variables or
references, as described in R6 – High Resistance Input with Parallel Resistor (P311).
 Series 4
Series 4 has a smaller current source III (~ 4uA) available and higher resistance measurement range is possible.