Orban OPTIMOD-FM 8500S Operating Manual page 290

6-8
TECHNICAL DATA
Remote Interface and RS-232 Interfaces
Located on control board
A remote interface connector and circuitry implements remote control of certain
operating modes; Model 8500S OPTIMOD-FM has eight remote contact closure
inputs.
A valid remote signal is a momentary pulse of current flowing through remote
signal pins. Current must flow consistently for 50msec for the signal to be inter-
preted as valid. Generally, the 8500S will respond to the most recent control op-
eration, regardless of whether it came from the front panel, remote interface, or
RS-232.
Component-Level Description:
After being current limited by resistors, the GPI control signals are applied to
two quad optoisolators, U17, U19, and then to the control circuitry.
Transceiver U12 interfaces the RS-232 signal levels at SERIAL DB-9 connector J5
to/from the TTL levels of the corresponding pins of the SC520 microcontroller.
U12, U17, and U19 are socketed for easy field replacement in the event of
overload, lightning damage, etc. All other circuitry is surface-mount and is not
field-repairable.
Switch Matrix and LED Indicators
Located on display board
Eleven front panel pushbutton switches are arranged in a matrix, configured as
three columns and four rows. These switches are the primary element of the
physical user interface to the 8500S control software. The host microprocessor
controls the system setup and function of the DSP according to the switch/rotary
encoder entered commands, the AES status bits from the digital input signal, the
RS-232, and the remote control interface status. The microprocessor updates the
LED control status indicators accordingly.
Component-Level Description:
S1-S11 are the front panel pushbutton switches. CR11-CR15 are the front panel
LED control status indicators. The control microprocessor communicates with
these components through the general-purpose bus.
LED Meter Circuits
Located on display board
The meter LEDs are arranged in an 8x16 matrix, in rows and columns.
Each row of LEDs in the matrix has a 1/8 duty cycle ON time. The rows are multi-
plexed at a fast rate so that the meters appear continuously illuminated. Via the
general-purpose bus, the DSP sends meter data values to the control microproc-
ORBAN MODEL 8500S