46112/113-0299 <90-00032>
P
AGE
3
46112
SynchMaster D
ATA
C
ONTROLLER
M
ODULE
The 46112 SynchMaster Module consists of:
RS-422 Drivers and Receivers
The RS-422 drivers and receivers are on a subassembly board
that mounts on the main PC board. The RS-422 drivers and
receivers provide data signal transformation from the module’s
internal TTL data bus to the specific parameters of the RS-422
interface.
A Clock
The RS-422 transmit and receive paths are clocked through the
main PC board because the line side data transmission equip-
ment is synchronous.
Terminating Resistors
Three subassembly board straps, designated X1, X2 and X3
provide for termination resistors. When you place the straps in
the “T” position a terminating resistor connects across the
RS-422 differential inputs. When you place the straps in the
“O” position you do not connect the terminating resistor.
Framing Generator and Detector
The framing generator inserts framing information into the
transmitted data. The framing detector reads the incoming data
and properly sequences the data to and from the microprocessor.
Proper sequencing prevents the data from individual ports
becoming intermixed.
Microprocessor
The microprocessor is resident for completing asynchronous/
synchronous conversion of the data as well as multiplexing the
data.
Status Indicating LEDs
The 46112 SynchMaster module’s green status indicating LEDs
are designated as follows:
¨
TX INSERT
When data is transmitted to a port config-
ured for the 46112 SynchMaster module, the TX INSERT
LED will light.
¨
TX REPEAT
When lit, the TX REPEAT LED indicates
that data is not being transmitted at the site. Either the TX
REPEAT or the TX INSERT will be on alternatively.
¨
RX SYNCH
Refer to the margin note to the left.
N
OTE
:
In the event of a failure, as well
as during installation, the RX
SYNC LED is an important indi-
cation of the soundness of the
64KB side of the SynchMaster
system. This LED appears as ei-
ther on or off if there is no syn-
chronization signal detected.
When the 46112 SynchMaster
receives a good synchronization
signal the RX SYNC LED ap-
pears to turn on solid.
A closer examination however,
reveals that the LED is actually
alternating on and off at a very
high rate. The LED appears to
“flicker” slightly.
CIRCUIT DESCRIPTION
