Omega Multifunction Indicator-Simulator User Manual
15
The microprocessor recognizes if the D/A converter is generating a voltage signal higher or lower than the input signal
and gives correcting instructions to keep the input amplifier output on the nearest value to zero. In the above conditions
the microprocessor acknowledges the value of the input signal as equivalent to the setting of the digital to analog
converter.
and gives correcting instructions to keep the input amplifier output on the nearest value to zero. In the above conditions
the microprocessor acknowledges the value of the input signal as equivalent to the setting of the digital to analog
converter.
+
-
IN
D/A
µ
P
Display
Ouput buffer / input amplifier
4.4 Microprocessor
The microprocessor handles all the logic functions of the instrument, performs the linearization for non linear
transducers, compensates for the reference junction temperature, drives the digital display and acknowledges all
operator instructions.
The heart of the circuit is a single-chip microcomputer that utilizes HCMOS technology to provide the low power
characteristics and high noise immunity of CMOS plus the high speed operation of HMOS.
The microcomputer provides highly sophisticated, on- chip peripheral functions including: 256 bytes of static RAM, an 8
channel analog to digital (A/D) converter (used to read the Rj value, the setting of the input comparator, the battery
package voltage and the value of the two membrane slidewires), a serial communication interface (SCI) subsystem, and
a serial peripheral interface (SPI) subsystem.
The microprocessor works with an 8-bit communication bus to the EPROM and EEPROM memories and is interfaced
with a decoder, a latch of address and an inverter-driver.
transducers, compensates for the reference junction temperature, drives the digital display and acknowledges all
operator instructions.
The heart of the circuit is a single-chip microcomputer that utilizes HCMOS technology to provide the low power
characteristics and high noise immunity of CMOS plus the high speed operation of HMOS.
The microcomputer provides highly sophisticated, on- chip peripheral functions including: 256 bytes of static RAM, an 8
channel analog to digital (A/D) converter (used to read the Rj value, the setting of the input comparator, the battery
package voltage and the value of the two membrane slidewires), a serial communication interface (SCI) subsystem, and
a serial peripheral interface (SPI) subsystem.
The microprocessor works with an 8-bit communication bus to the EPROM and EEPROM memories and is interfaced
with a decoder, a latch of address and an inverter-driver.
4.5 Firmware
The operating system firmware handles all logic instructions to the internal peripheral circuits and performs the
computation of the linearization equations.
The application system firmware is resident on the non-volatile memory (EEPROM) of the microprocessor chip. It is used
to store the installation parameters (autocalibration data, programs data, etc.)
computation of the linearization equations.
The application system firmware is resident on the non-volatile memory (EEPROM) of the microprocessor chip. It is used
to store the installation parameters (autocalibration data, programs data, etc.)
4.6 Digital
display
The digital display, mounted on an auxiliary board, uses high contrast LCD technology (STN liquid). Character
generation is made by a secondary dedicated microprocessor driven by two integrated circuits with signal input from the
bus of the main microprocessor.
The 16 characters are displayed with a 7x5 dot matrix. On request, CL526 can be equipped with a backlight device for
easy readings in poor light conditions.
generation is made by a secondary dedicated microprocessor driven by two integrated circuits with signal input from the
bus of the main microprocessor.
The 16 characters are displayed with a 7x5 dot matrix. On request, CL526 can be equipped with a backlight device for
easy readings in poor light conditions.
4.7
Digital to analog converter
A 14-bit digital to analog device, driven directly by the microprocessor converts the digital value of the selected
parameter into an analog current output.
The current signal is converted into a voltage signal across a resistance strip network.
Two low thermal emf relays select one of the four available output points as a function of the selected range. The ranges
are:
parameter into an analog current output.
The current signal is converted into a voltage signal across a resistance strip network.
Two low thermal emf relays select one of the four available output points as a function of the selected range. The ranges
are:
-18
to
+22 mV
Tc type R, S, B, T and the negative portion of all Tc’s
-0.2
to
+54 mV
all other thermocouples
-0.2
to
+100,1 mV
100 mV range and Rtd
-2
to
+1001 mV
1000 mV range and 0-20 mA range
-0.02 to
+10.010 V
10 V range
The above signal, through an output buffer, is sent to an integrated circuit that will generate the voltage or current
requested by the operator keyboard settings.
requested by the operator keyboard settings.