Operating Behavior, Diagnostics; Control - Beckhoff EL3692 Documentation

2 channel resistance measurement terminal

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Manual (193 pages)

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Table of Contents

Commissioning

• as 32-bit integer measuring range-dependent value, with 24-bit content "fixpoint"

Explanation:

Each of the 9 measuring ranges of the EL3692 extends over 1 decade (e.g. 1 .. 10 Ω). The regular

value range of value extends from x0 .. x00 7F FF FF for each measuring range with "x00 7F FF FF ≈

full-scale value".

In Autorange mode the measuring range is exceeded by up to 10%, in order to ensure the measuring

range changeover; referred to as extended measuring range.

Note the status information.

The following example is for the measuring range 1 .. 10 Ω:

Input resistance

32-bit value

0 Ω

x00 00 00 00

10 Ω

x00 7F FF FF

10 .. 11 Ω

> 11 Ω

x00 8C CC CB

Please note that that the relative measuring error is very large near the lower end of the measuring range.

For measurements within the range of less than 10% of the lower end of the measuring range the next lower

measuring range should 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 [} 111]

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 [} 136]), 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 [} 111] and Important CoE entries

[} 132].

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