Maintenance
M7/M7L/M7LT Modular Satellite Modem
2-10
M7/M7L/M7LT - Rev. 0.05
NOTE: Data Interface Connections:
1. The modulator and demodulator fault alarms are Open Collector TTL outputs used to
interface to redundancy control equipment.
2. The Shield is normally connected to the cables shield at one end of the cable only.
Connecting at the DCE end only prevents ground loop currents being carried on the shield.
3. The synchronous RS-232 connection is limited to 128 kbps.
2.3.8.1.2.
Serial Interface Overhead Channel Connection (J10)
On the Synchronous Serial Data Interface, the connection to the overhead data is on an auxiliary
connector located on the rear panel, the 25-
pin male “D” sub connector J10. The pin-out of this
connector is determined by the selected multiplexer mode. The pin definitions are defined in Table
2-7 through Table 2-10.
NOTE: The FIFO External Clock pins are an input to the modem. An input at the receive data rate
can be used to clock data out of the demodulator FIFO buffer. An input at the transmit data
rate can be used to provide a transmit send timing clock which the modem will phase locked
to (if within acceptable range). The send timing signal is still an output from the modem, but in
this case will be at the input signal rate. Both functions can be used simultaneously if the
transmit and receive data rates are the same.
Table 2-7
– Serial Interface Overhead Channel - IBS Standard Mux - RS-232 (J10)
J10
Pin #
Signal Name
Use
Direction
1
Ground
All
Ground
2
ESC Send Data
RS-232 Standard Mode
Connection (synchronous)
Input
3
ESC Rcv Data
RS-232 Standard Mode
Connection (synchronous)
Output
5
ESC Send Clock
RS-232 Standard Mode
Connection (synchronous)
Output
7
Ground
Ground
Ground
8
ESC Rcv Clock
RS-232 Standard Mode
Connection (synchronous)
Output
9
Primary Interface
External Clock+ (B)
FIFO External Clock input ‘+’
or ‘B’ line. RS422 level
Input
15
Ground
Ground
Ground
17
Ground
Ground
Ground
21
Primary Interface
External Clock- (A)
FIFO External Clock input ‘-‘ or
‘A’ line. RS422 level
Input
Table 2-8
– Serial Interface Overhead Channel - IBS Standard Mux - RS-485 (J10)
J10
Pin #
Signal Name
Use
Direction
1
Ground
All
Ground
2
ESC Send Data+ (B)
RS-485 Standard Mode
Connection (synchronous)
Input
3
ESC Rcv Data+ (B)
RS-485 Standard Mode
Connection (synchronous)
Output
4
ESC Send Data- (A)
RS-485 Standard Mode
Connection (synchronous)
Input
5
ESC Rcv Data- (A)
RS-485 Standard Mode
Connection (synchronous)
Output
