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SERIAL INTERFACE CONNECTIONS
2.9.1 4809A Serial Connections
The 4809A’s serial port is a DTE (Data Terminal Equipment) interface on
a 26-pin male ribbon connector (J3) and a DB-25P connector (J4). The
26-pin male ribbon connector is for compatibility with the earlier 4809’s.
The DB-25P connector allows standard DB-25S connectors to be used with
the 4809A. RS-232 and RS-422 (RS-485) signal selection is made by setting
jumpers on the 4809A. Refer to section 2.13 for jumper setting instructions.
Table 2-2 shows the 4809A’s signal-pin assignments and signal directions.
Figure 2-9 shows the pin layout for connector J3.
2.9.1.1 4809A LED Outputs
The 4809A’s TALK and LSTN LED driver outputs are provided on pins
17 and 21 on connector J3 and J4 to drive remote LEDs. Each signal is
low true and can sink 3 mA. Use a resistor in series with 5 Vdc to limit
the current to LED. Connect the LED cathodes to the driver signals. The
recommended resistor value is 1500 ohms for 5 Vdc. Connect the 5 volt
return line to pin 7.
2.9.2 4819A Serial Connections
The 4819A has two right-angle 9-pin connectors for its RS-232 interfaces.
Connector J2 is the external serial connector that protrudes through the
rear panel. Connector J3 is the internal serial connector for connecting the
4819A to the serial device. Signal pin assignments for both connectors are
shown in Table 2-3.
2.9.2.1 4819A Rear Panel Connector J2
Rear panel connector J2 is a DE-9P connector with DTE type signal as-
signments similar to the signals in a PC COM port. Signal TxD on pin 2 is
the output signal and RxD on pin 3 is the input signal. RTS and DTR are
pulled high to the ‘ON’ state. DTR is internally jumpered to CTS.
Содержание 4809A
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