46034-0997 <90-00030>
P
AGE
3
The data bus consists of six individual, switch selectable data
lines which route the data to the desired ports. Data received
from the data bus applies to one input of a two-input OR gate.
The other OR gate input connects to switch S22 for full- or
half-duplex operation.
When switch S22 is in full-duplex mode (switch open), a con-
stant low applies to the input, which passes all data received
from the data bus to the port transmit circuitry. When S22 is in
half-duplex mode (switch closed), the input operates with the
port receive circuitry.
When the port is not receiving data, the input holds in the low
state and the OR gate passes data received from the data bus.
When the port receives data the input fluctuates between high
and low, enabling and disabling the OR gate and preventing port
data transmission.
The OR gate output applies to a driver that transmits data
through the RS-232 or RS-422 interface, depending on the strap
selection of mini-jumpers 1B through 8B. The signal illuminates
the front panel TX LED.
The ninth data port provides a mounting for installing various
communication subassemblies. With the five six-lever DIP
switches, the port supports the following interfaces:
♦
TTL
♦
RS-232
♦
RS-422
♦
RS-485
♦
202 tone modem
The ninth data port has CA (pin 36) and CF (pin 18) control
leads for RS-232 subassembly applications.
When using a tone modem subassembly, strap C may be config-
ured to allow modem control by RTS command or strapped for
RTS always enabled. Use strap D for full- or half-duplex opera-
tion. When the strap is in the 1 position, the port operates in
full-duplex mode; when in the 2 position, the port operates in
half-duplex mode.
When the ninth data port is used with a bypass card subassem-
bly, front panel LEDs indicate RXD (receive data) and TXD
(transmit data) activity. When the ninth port is used with any
other communications subassembly, module and subassembly
LEDs indicate receive and transmit activity. Refer to the subas-
sembly documentation for LED operation information.
The 46034 Hubbing Module has an on-board power supply that
operates on -21 to -56 VDC input power. The unit supplies
±12 VDC and +5 VDC that powers the module circuits and an
on-board subassembly.
CIRCUIT DESCRIPTION