Carrier Frequency configuration and synchronization

How to set up carrier frequency measurement in A106 modules and how to synchronize to avoid noise.

The A106 module supports the supply of sensors with direct volt-
age (DC) or carrier frequency (CF).

If you are using several modules of this type and set carrier fre-
quency supply, you should synchronize the carrier frequencies of
the modules, because otherwise crosstalk can occur between the
supply lines and the signal inputs of different modules. This then
leads to beats in the measurement signal.

The A106 provides bridge measuring (full, half and quater) for both

  • CF (carrier frequency) excitation - either 600 Hz or 4,8 kHz
  • DC excitation

When using CF principle, the A106 offers the possibility to synchronize the inputs within the same module, and also for other A106 modules on the same UART. In this case 1 input is acting as “master” (internal synchronized) and provides the clock of CF for all other inputs (external synchronized).

It is only allowed to set up one input as master-input on one UART. The clock for all other modules is provided via the Q.bloxx socket on the Sync lines (the master input can be on any of the connected A106 modules). All external synchronized inputs have to be configured with the same frequency as the internal synchronized (master-)input.

After selecting a carrier frequency, you have three methods of

1. No sync.(hronization)
This setting is practicable when you are only using one mod-
ule with carrier frequency supply. Within a module all carrier
frequency generators are automatically synchronized.

2. Internal sync.(hronization)
Set this type of synchronization for one module. The module
then becomes the master to which all other modules synchro-

3. External sync.(hronization)
Specify this type of synchronization for all other modules so
that they synchronize to the master.
For synchronization the Sync A and Sync B lines in the socket are
used (Fig. 4-6, page 29).
We recommend that only one variant of the carrier frequency is
used, i.e. do not mix 600 Hz and 4800 Hz.
Do not forget to save these settings in the module and the Test