ADC
The ADC is used as an on-board oscilloscope.
During normal WorldFIP operation the ADC will be deactivated with the
related power supplies turned off.
In case of a failing segment, the macrocycle would change to a simple
predefined one (ex. a presence variable request to nodes 1..255) and the
ADC would be turned on and connected to the secondary side of the
transformer. The ADC could also connect to the primary/bus side of the
transformer; that could be risky though.
To simplify the design of the board, the same ADC used in the FMC-ADC
has been selected.
Figure 1 shows a WorldFIP frame as it appears on the primary side of the
transformer. Each signal of the differential pair is 0 +-2.3V.
The calculated rising time is 70 ns; through a simple rule of thumb this
translates to a bandwidth of 5
MHz.
> Figure 1: probing on the FieldTR primary side
Figure 2 shows the frame on the secondary side of the transformer. Each
signal of the differential pair is at 2.3
+-1.5V.
> Figure 2: probing on the FieldTR secondary side