Comtech EF Data CDM-550T - Manual (Page 150)

CDM-550T Satellite Modem Revision 3
Async Overhead Option MN/CDM550T.IOM
C.2 Electrical Interface
The electrical interface is 3-wire RS-232 (Rx Data, Tx Data, and ground). No flow control is
provided. The async character format is fixed at 8 data bits, no parity, 1 stop bit, (8-N-1), full
duplex.
C.3 Pin Numbering
Looking at the rear panel, pin 1 is on the right-hand side:
Rx D Gnd Tx D
(Input) (Output)
• • •
Pin 1
C.4 Baud Rates
The main channel data rate versus async channel baud rate is as follows:
All modes except 21/44 and 5/16 Turbo:
<50 kbps - option disabled
50 to 99.999 kbps – 1200 baud
100 to 199.999 kbps – up to 2400 baud
200 to 399.999 kbps – up to 4800 baud
>399.999 kbps – up to 9600 baud
(Rate 1/2 BPSK modes are limited to 4800 at rates above 550 kbps)
21/44 and 5/16 Turbo modes:
<150kbps - option disabled
150 to 299.999 kbps – 1200 baud
300 to 599.999 kbps – up to 2400 baud
>599.999 kbps – up to 4800 baud
C.5 Selecting Async Mode
Access to this mode is not via the normal front panel menus or remote control. Customers
wishing to order modems from the factory may request that their units be pre-configured to
operate in this mode when they are shipped. Users who have existing units, and that have
Software Version 1.19 installed, may select Transparent Async mode from the FACTORY,
SPECIALS menu. The FACTORY sub-menus contain features and operating modes that may
be specific to particular customers of Comtech EF Data, and includes diagnostic modes that may,
in certain circumstances, render the modem inoperable. It is our policy, therefore to require a
special combination of keystrokes for FACTORY access, which we do not publish. Therefore, if
C–2