Access methods, Direct access, Indirect access – Comtech EF Data UT-4579 User Manual
Page 65: B.3 access methods, B.3.1 direct access b.3.2 indirect access, B.3 a
UT4579 X-Band Up Converter
MN/UT4579.IOM
Remote Control
Rev. 0
49
B.3 A
CCESS
M
ETHODS
Converters may be accessed directly by using a physical address or indirectly through a
backup converter by using a virtual address.
B.3.1 D
IRECT
A
CCESS
Converters may be directly accessed by the EIA-232C interface or by the EIA-485
interface in a bus configuration.
B.3.1.1 EIA-485
In this control network, all converters including the backup converter are paralleled on a
common EIA-485 cable. Both up and down converters can be mixed on the cable as long
as each converter has a unique physical address. Only one EIA-485 port is required on
the system's monitor and control computer. If a change is initiated directly to a converter
in a redundancy subsystem, the backup converter will detect the change via the High
Speed Bus and update its backup tables.
B.3.1.2 EIA-232C
For EIA-232C control, a direct EIA-232C cable connection is made to each converter to
be accessed. If an external Monitor and Control Computer is used, one EIA-232 port per
converter is required. This mode is commonly used with an ASCII terminal for bench
testing.
B.3.2 I
NDIRECT
A
CCESS
Converters in Redundancy Mode may be addressed indirectly by adding a virtual address
to the backup converter's physical address. The virtual address corresponds to
converter's position in the redundant subsystem. The backup converter recognizes the
virtual address and executes the command via the high speed bus.
B.3.2.1 EIA-485
To control by using the EIA-485 interface, one or more backup Converter is connected to
a system's monitor and control computer or ASCII terminal with a common EIA-485 bus
cable. Both up and down backup converters may be mixed on the cable as long as each
has a unique device address. In order to indirectly address an online converter in the
subsystem, a virtual address must be provided. The virtual address corresponds to the
converter's position in the chain beginning with number 1. Virtual addressing is only
recognized by a backup converter. Only one EIA-485 port is required on the monitor and
control computer.