A.2.2 tia/eia-232 (rs-232), A.2.3 ethernet (100base-tx), A.3 access methods – Comtech EF Data DT-4500-A Series User Manual
Page 112: A.3.1 direct access
DT-4500-A Series Downconverters
Revision 1
Appendix A
MN-DT4500A
A–2
intended) will reply. The Target enables its output line driver and transmits its return data
packet back to the Controller in the other direction on the physically separate pair.
EIA-485 (Full Duplex) summary:
•
Two differential pairs - one pair for Controller-to-Target, one pair for Target-to-Controller.
•
Controller-to-Target pair has one line driver (Controller), and all Targets have line-receivers.
•
Target-to-Controller pair has one line receiver (Controller), and all Targets have tri-state
drivers.
A.2.2 TIA/EIA-232 (RS-232)
This is a much simpler configuration in which the Controller device is connected directly to the
Target via a two-wire-plus-ground connection. Controller-to-Target data is carried, via EIA-232
electrical levels, on one conductor, and Target-to-Controller data is carried in the other direction
on the other conductor.
A.2.3 Ethernet (100BASE-TX)
The unit implements a Telnet server that will accept Telnet terminal connections using
Transmission Control Protocol (TCP) on port 23. After entering the username (default: comtech),
and the password (default: comtech) the Telnet server will accept the same syntax used by the
serial interfaces.
A.3 Access Methods
Downconverters may be accessed directly by using a physical address or indirectly through a
backup downconverter by using a virtual address.
A.3.1 Direct Access
Converters may be directly accessed by the EIA-232 interface or by the EIA-485 interface in a
bus configuration.
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.