SMAR TT302, Installation, Operation & Maintenance Instruction Manual

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TT302 – Fieldbus Temperature Transmitter
2-2
(CPU) Central Processing Unit, RAM, PROM and EEPROM
The CPU is the intelligent portion of the transmitter, being responsible for the
management and operation of measurement, block execution, self-diagnostics and
communication. The program is stored in a PROM. For temporary storage of data there is
a RAM. The data in the RAM is lost if the power is switched off. However there is a
nonvolatile EEPROM where data that must be retained is stored. Examples, of such data
are trim, calibration, block configuration and identification data.
Communication Controller
It monitors line activity, modulates and demodulates communication signals and inserts
and deletes start and end delimiters.
Power Supply
Takes power of the loop-line to power the transmitter circuitry.
Power Isolation
Just like the signals to and from the input section, the power to the input section must be
isolated. Isolation is achieved by converting the DC supply into a high frequency AC
supply and galvanically separating it using a transformer.
Display Controller
Receives data from the CPU informing which segments of the Liquid Crystal Display,
should be turned on.
Local Adjustment
There are two switches that are magnetically activated. They can be activated by the
magnetic tool without mechanical or electrical contact.
Figure 2.2 - LCD Indicator
TT2EM202.CDR