Raveon RV-M7 Spécifications télécharger pdf (Page 15)

RV-M7 Technical Manual

4.6 Optional EIA-485/RS-485 Serial I/O

RS-485 Connector Pin Out

RS-485 is a two-wire connection, with the pair of wires transmitting and receiving data. With the RS-485

enabled (ATIO 2 command), the 9-pin serial I/O connector on the front of the M7 is a female 9-pin D-

subminiature connector having the following pins configuration.

Front-view of DB-9 connector on modem (female)

Pin #

Name

Direction

Function

Level / Specification

Do not connect

Do not connect this pin to anything.

B (-)

I/O

Inverting RS-485 data in line

Out -

out

Connect to pin 2

A (+)

I/O

Non-inverting RS-485 data out line

GND

Ground

Connect to earth ground.

Do not connect

Do not connect this pin to anything.

Out +

out

Connect to pin 4

Vin

In/Out

DC Power

DC Power in or out if unit is powered using DC

in jack.

The RS-485 differential line consists of two pins, A and B.

A TxD+/RxD+ non-inverting pin which is positive (compared to B) when the line is idle.

B TxD-/RxD- aka inverting pin which is negative (compared to A) when the line is idle.

Configuring

To configure the M7 modem for RS-485 operation, use the ATIO x command. ATIO 2 sets the serial port

for standard RS-485, full duplex. ATIO 3 sets the serial port for RS-485 simplex mode. In most cases, RS-

485 simplex is preferred (ATIO 3). In simplex RS-485 mode, the M7’s serial data receiver is internally

disabled whenever it sends a character out the serial port, so that it will not receive its own data. For

most application use the RS-485 simplex mode, ATIO 3. If you are using two M7 modems with RS-485

on both units, you must use the simplex RS-485 mode instead of the duplex RS-485 mode, or the

modems will enter an infinite loop-back condition.

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Raveon RV-M7 Spécifications Page 15

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