Comtech EF Data SDM-2020 - Manual (Page 116)

9-1
Chapter 9. ASI/RS-422 D ATA INTERFACE
9.1 ASI/RS-422 (A
SYNCHRONOUS
S
ERIAL
I
NTERFACE AND
S
ERIAL
D
ATA
I
NTERFACE
The following paragraphs describe the ASI/RS-422 Data Interface.
9.1.1 A
PPLICABLE
D
OCUMENTS
Applicable specifications, as referenced herein, include:
TM1449 Interfaces for CATV/SMATV Headends and Similar
Professional Equipment
RS-422 Electrical Characteristics of Balanced Voltage Digital
Interface Circuits
EIA-530 High Speed 25-Position Interface for Data Circuit -
Terminating Equipment
ETS 300 421 Digital Broadcasting Systems For Television, Sound
And Data Services; Framing Structure, Channels
Coding And Modulation For 11/12 GHz Services
9.1.2 D
ESCRIPTION
This data interface is a plug-in module that inserts into the rear of the SDM-2020
Modulator or SDM-2020 Demodulator chassis. It provides physical and electrical
connection between the external terrestrial circuit and the internal circuitry of the
modulator or demodulator. The plug-in interface has full duplex capability, but is
automatically configured for simplex-transmit or simplex-receive operation.
The ASI/RS-422 interface combines two electrical and physical interfaces into a single
assembly. The ASI section provides DVB-compliant interface with BNC connectors,
while the RS-422 section supports serial communications through a standard 25-pin D
connector per EIA-530. Operation for either ASI or RS-422 is selected by programming
the unit from the front panel keypad/LCD or from the remote port. Only one of the
interface types is active at a time
.