DESCRIPTION AND OPERATION
HSS MODULE CIRCUITRY
I-E96-322A
2 - 5
HSS MODULE CIRCUITRY
The following text explains the operation of the seven func-
tional blocks that make up the HSS module.
I/O Expander Bus Interface
The I/O expander bus interface enables communication
between the processor module and the HSS module. This com-
munication channel is an eight-bit parallel data bus with two
control lines. A Bailey designed integrated circuit performs the
communications protocol for interfacing the data and status
information to the processor module. It performs address com-
pare, read/write strobe generation and contains bus drivers
and receivers.
The I/O expander bus address is selected by setting a
dipswitch on the HSS module. The address byte precedes every
data transfer. The I/O expander bus integrated circuit does an
address comparison before allowing data to transfer on the I/O
expander bus. If the addresses match, the MFP module can
strobe data to or from the I/O expander bus.
Figure 2-2. Functional Block Diagram
RAISE/LOWER
CONTACT INPUTS
ISOLATION/
DEBOUNCE
MICROPROCESSOR
LVDT OSCILLATOR
D/A CONVERTER
STATUS AND
DATA STORAGE
ISOLATION/
DEBOUNCE
D/A CONVERTER
POSITION ERROR
AMPLIFICATION
DITHER OSCILLATOR
SERVO STATUS
SERVO SELECT
LVDT STATUS
LVDT SELECT
DEMODULATOR
SAMPLE/HOLD
A/D CONVERTER
TRIP BIAS
CONTACT
INPUT
OUTPUTS TO
SERVO VALVE
COILS
LVDT
SECONDARIES
UNSCALED
POSITION
OUTPUT
TP25407A
DIGITAL I/O
POSITION DEMAND
POSITION FEEDBACK
XBUS
I/O
EXPANDER BUS
MANUAL
OUTPUT
LVDT
PRIMARIES
SCALED 4-20 mA
POSITION OUTPUT
DIGITAL I/O
DATA
BUS
