DESCRIPTION AND OPERATION
SAC STATION I/O CIRCUITRY
I-E96-117B
2 - 13
ratio index has a range from zero to 100. If the set point track
specification of function code 80 is set, the ratio index value
remains fixed until the set point track is disabled.
SAC STATION I/O CIRCUITRY
The analog control station interfaces an MFP module to a pro-
cess. Its circuitry provides process monitoring and hard station
control in parallel with a CIS module. The eight blocks that
make up the functional operation of SAC circuitry are (see Fig-
ure
):
•
Microprocessor and support circuitry.
•
Serial interface.
•
Faceplate components and display driver.
Figure 2-7. Block Diagram of SAC Station Circuitry
DAC
TRANSMITTER
RECEIVER
RS-485
CURRENT
SOURCE ERROR
COMPENSATION
ANALOG OUTPUT
RAISE/LOWER
RELAYS
M/A SIGNAL
FILTER AND
ERROR
COMPENSATION
ANALOG INPUTS
SWITCHING
POWER
SUPPLY
SCI
ADC
RAM
RAM
LATCH
MEMBRANE
KEYPAD
DISPLAY DRIVER
MULTIPLEXER
ALPHANUMERIC
BAR GRAPHS AND
ANNUNCIATORS
ROM
MICROPROCESSOR
SERIAL
COMMUNICATION
LINK TO MFP
I/O POWER
24 VDC
+15 VDC
+5 VDC
+230 VDC
-9 VDC
FEEDBACK
AI1
AI2
AO
RAISE
BYPASS
CIRCUITRY
LOWER
M/A
PWR
M/A
SIG
M/A
COM
FACEPLATE COMPONENTS AND
DISPLAY DRIVER
T00292A