Beckhoff EL3692 Manual page 143

• as 32 bit integer, measuring range dependent value, with 24 bit content "fixpoint".
Explanation:
The 9 measuring ranges of the EL3692 are named after their recommended range of use e.g. 1 ... 10
Ω, but they all measure down to 0 Ohm. The value range of Value thus extends over x0 ... x00 7F FF
FF for each measurement range, with "x0 = 0 ohms" and "x00 7F FF FF ≈ nominal full scale".
However, the nominal measuring range is exceeded by up to 10% in autorange mode to ensure
measuring range switching, so-called "extended measuring range".
The information in the status must be observed.
In the following an example for the measuring range "1 ... 10 Ω":
Input resistance
0 Ω
10 Ω Nominal
measuring range
end value
10 .. 11 Ω extended
measuring range
> 11 Ω
Please note that the relative measurement error is very large at the lower end of the measuring range. When
measuring in the range < 10% of the nominal measuring range end value, the next lower measuring range
should therefore be used. The autorange function works accordingly.
• as 32-bit fixed-point float-value with mantissa and exponent, measuring range-independent "float"
Explanation:
This 32-bit variable can be linked directly with a FLOAT variable of the PLC according to IEC61131.
The conversion takes place in the EL3692; no measuring range-dependent conversion by the user is
required.
See additional information on page Process data [} 149]
6. You have to check the correct operation of the range change function in the autorange opration mode for
all test specimens. This is mandatory in the special case, if test specimens with very different resistance/
capacity/inductive values are connected to channel 1 and 2 (> 3 measuring ranges). An unoccupied channel
will measure in the measuring range 7 (1 MΩ .. 10 MΩ).
This can be compensated channel-wise by the extension of the delay time (CoE 0x80n0:31 [} 168]), if the
automatic setting is not sufficient. The delay time should be increased stepwise for the channel, which has
not the optimal range setting.
7. During the operation, the channel-wise process data value has to be verified by checking of the state
variables Error, DataInvalid and SteadyState.
For further configuration in TwinCAT please refer to sections Process data [} 149] and Important CoE entries
[} 165].
EL3692
32-bit value Interpretation
x00 00 00 00 0
x00 7F FF FF 8.388.607
x00 8C CC CB 9.227.467
Version: 3.1
Commissioning
Status bits
Extended Range = 0
Overrange = 0
extended range = 1 "extended
measuring range"
Overrange = 0
Extended Range = 1
Overrange = 0
Extended Range = 0
Overrange = 1
143