Rockwell Automation T80004 Application Note Field Loop Configuration - Manual (Page 5)

Trusted
TM
AN-T80004 Field Loop Configuration
Issue 10 Jun 13 AN-T80004 5
Analogue Inputs
Line monitoring
Field loops providing analogue input signals to a Trusted
TM
system do not require line monitoring
components to be fitted to the field device, because the measured current acts as the proof of the
presence of the line. However, analogue inputs should be checked for accuracy periodically because
partial shorts will offset the measurement.
T8431 and T8432 Termination Options
The T8431 and T8432 Trusted TM Analogue Input modules are designed to monitor input signals in the
range 0-6V (0 to 22mA via a 250R resistor). The input zero volt reference wires are linked together
across the module, so although there is isolation between field and system, there is no isolation
between channels. The T8431 has 40 triplicated input circuits and the T8432 has 60 dual input circuits.
Field termination assemblies are available to provide field terminations for most applications.
The T8830 allows connection of system powered two wire devices to a T8431. It requires an FTA
cable, TC-201, 203, 501 or 503, to connect to its cable socket. It does not provide a zero volt reference
to field devices, so it is only able to directly connect to system powered devices.
The T8831 is similar but replaces the fuse with a resistor, limiting available power for non-incendive
applications (non-incendive hazardous area specifications specify limited loop power and are used in
the Americas).