ABB UFC921A101 programmable control module
Analogue Input Modules
The types of analogue input modules
available are:
• 32 channel isolated 0 to 5Vdc and 0
to 10Vdc TMR
(0 to 40mA and 0/4 to 20mA with
burden resistor at the termination
card)
Each analogue input signal path
contains three identical circuits of:
• Isolation
• Noise Filtering
• Multiplexing
• Amplification
• Analogue to digital conversion
and each of the three circuits is
supervised by a micro-controller.
The three circuits synchronously
measure the input signals, vote the
data and transmit the data to the
processors.
The processors condition the input
signal data, making any necessary
corrections, and then select the
mid-value from the three sets of input
data. This mid-value is then used by
the control program.

Analogue Output Modules
• 4 channel – 12 bit resolution
4–20mA TMR
Each of the three Triguard SC300E
processors sends voted output voltage
data to the analogue output modules.
The commands are received via
the bus system by the three
micro-controllers on each module.
Each micro-controller controls a digital
to analogue converter which drives
two elements of the six element
output voting network. Each element
of the six element voter is an isolated
field effect transistor operated within
its linear range. The final output of
the field device is selected as the
mid-value from the three circuits of
output data.
Feedback to each of the three
micro-controllers provides continuous
checking for correctness. Diagnostics
declare any fault to the processors for
maintenance information and action.