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Commissioning
Measuring range
-1 (10 mΩ -100 mΩ)
0 (100 mΩ -1 Ω)
1 (1 Ω-10 Ω)
2 (10 Ω-100 Ω)
3 (100 Ω -1 kΩ)
4 (1 kΩ -10 kΩ)
5 (10 kΩ -100 kΩ)
6 (100 kΩ -1 MΩ)
7 (1 MΩ -10 MΩ)
Table 1: Measuring ranges and associated measuring currents and voltages
5.7.2
Capacitive and inductive influences
Internal and external capacitive and inductive influences may distort the measurement reading through their
dynamic characteristics. In order to minimize these influences, a delay is set between switching on of the
measuring current and the start of the measurement. The delay time can be set via object 0x80n0:31 [} 136]
and switched on or off for each channel via object 0x80n0:05 [} 136]. The delay time is set in 0x80n0:37 as a
channel-specific value. In the measuring ranges -1 to 5 this value is multiplied with 20 ms, in the measuring
ranges 6 and 7 with 50 ms. The standard delay time is therefore 200 or 500 ms.
The delay time does not become active if two consecutive measurements take place in the same measuring
range and on the same channel.
The delay time largely allows charging processes at the test specimen to complete. Once the charging
process is complete based on the sensitivity setting (steady-state tolerance object 0x80n0:3E [} 136] ), the
steady state bit is set to TRUE.
5.7.3
Heating of the test specimen
In the lower 3 measuring ranges the measuring current may result in heating of the test specimen. In the
upper measuring ranges the current through the test specimen is so low that heating of the test specimen is
not an issue.
Measuring range
-1 (10 mΩ -100 mΩ)
0 (100 mΩ -1 Ω)
1 (1 Ω-10 Ω)
Table 2: Power in the test specimen
5.7.4
Calculating the resistance value
The terminal calculates the value of the ADC (filtered, X
the manufacturer gain (A
calculations can be activated or deactivated via CoE object 0x8000:01 [} 136] and 0x8000:02 [} 136].
Y
=(X
- B
) * A
/ 0x10000
H
adc
H
H
Y
=(X
- B
) * A
/ 0x10000
A
H
U
U
This is followed by scaling for the INT value and the REAL value.
Extended measuring range
All measuring ranges have an option to extend the range by 10% beyond the upper limit. This range is used
to allow for the hysteresis of the Autorange function.
If the measured value is within extended measuring range, the Extended Range bit is set to TRUE.
116
Typical measuring voltage (max.) Typical measuring current.
~ 4.5 mV (3.0 V)
~ 45 mV (3.0 V)
~ 450 mV (3.0 V)
~ 16 mV (3.0 V)
~ 160 mV (3.0 V)
~ 1.6 V (3.0 V)
~ 16 mV (3.0 V)
~ 160 mV (3.0 V)
~ 1.6 V (3.0 V)
). The user offset (B
) and user gain (A
H
U
Version: 2.1
~ 45 mA
~ 45 mA
~ 45 mA
~ 0.16 mA
~ 0.16 mA
~ 0.16 mA
<< 16 µA
<< 16 µA
<< 16 µA
Max. power in the test specimen (alternating mode)
~450 µW (~220 µW)
~4.5 mW (~2.2 mW)
~45 mW (~22 mW)
) with the manufacturer calibration offset (B
adc
) are also taken into account. The two
U
) and
H
EL3692
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