Black Box ME1791A-F, User Manual

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ME1791A-F, ME1794A-F
2 Description
Table 1. Typical Transmission Ranges
19 AWG 24 AWG 26 AWG Data Rate
[kbps]
[km] [miles] [km] [miles] [km] [miles]
19.2 14 9 6 4 4 3
9.6 14 9 6 4 5 3
4.8 14 9 7 4 5 3
2.4 16 10 8 5 7 4
1.2 21 13 11 7 8 5
The modems incorporate innovative circuitry design, which enables the units to
operate without connection to the mains supply, by using ultra low power from
the standard RS-232/V.24 data and control signal voltages. The modem operates
fully even if only Transmit Data is connected (i.e. without the DTE sending Request
to Send or Data Terminal Ready signals). Both positive and negative signals are
generated in compliance with RS-232/V.24 standards, regardless of constantly low
or constantly high Transmit Data.
Table 2 provides the DCE connector pinout.
Table 2. DCE Connector Pinout
Pin Designation Function
1 DCD Data Carrier Detect (output)
2 RD Receive Data (output)
3 TD Transmit Data (input)
4 DTR Data Terminal Ready (input)
5 GND Ground
6 DSR Data Set Ready (output)
7 RTS Request To Send (input)
8 CTS Clear To Send (output)
9 RI (+V)
The low transmit level minimizes cross-talk onto adjacent circuits within the same
cable. Data is transmitted and received at a balanced impedance, ensuring
excellent immunity to circuit noise.
The line side of the modems offers connection to the RS-232 plug ground.
This may be connected to the shield of the STP wiring to provide end-to-end
ground continuity.
Table 3 provides the pinout of the RJ-45 line connector.