Black Box ME260A, Руководство пользователя

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CHAPTER 2: Introduction
2.2.3 O
PERATING
M
ODES
The Modular Modem Eliminator has three operating modes, which are described
below.
Interface-Converter Mode
The interface-converter mode lets you connect a Data Terminal Equipment (DTE)
device to a Data Communications Equipment (DCE) device that has a different
interface. A physical and electrical conversion between the DTE and DCE inter-
faces is performed. The data rate is determined by the equipment connected to
the Modular Modem Eliminator.
Modem-Eliminator Mode
In the modem-eliminator mode, the Modular Modem Eliminator is used to
connect two DTEs, thereby replacing two synchronous modems. The interface-
conversion function of the Modular Modem Eliminator allows connecting even
DTEs with different interfaces, in addition to the modem-eliminator function.
In this mode, the Modular Modem Eliminator fully emulates the operation of
two modems connected in a link (one for each DTE). This includes supplying
clock signals and handshaking control signals. The data rate is derived from an
internal oscillator, and is selected by means of a front-panel switch. Any standard
rate in the range of 48 kbps to 2048 kbps can be selected.
Both modules can also use external timing: With external timing, the Modular
Modem Eliminator accepts an external clock in the range of 1.2 to 2048 kbps. This
permits the transfer of system timing from one side to the other (clock locking).
The maximum range that can be achieved depends on the interface type, cable
type, and data rate, and can be up to 330 feet (100 m).
Elastic Buffer Mode
The elastic buffer mode is used to connect two independently clocked
plesiosynchronous DCEs via FIFO buffers. By providing bi-directional buffering of
data, the Modular Modem Eliminator reduces loss of data that would otherwise
occur because of the difference in clock rates. The two DCEs can have
similar or different interfaces, and the data rate can be up to 2048 kbps.