DS232_2

June 00

©2000 Reg. No. 227 4001, ENGLAND

Page 2

FM-232C-433

FUNCTIONAL DESCRIPTION

The RF Modem is designed to connect two DTE devices (e.g. PC’s). The RF Modem physical interface is a 9

pin DCE. The host communications RS232 operates at various baud rates, 8 data bits, 1 stop bit, no parity.

The DTE device must either support hardware CTS flow control, XON/XOFF flow control or if hardware flow

control is disabled then the user must be aware of the maximum buffer size of 56 bytes.

(note: if you use a null Modem to connect a DTE to a DCE using two RF Modems, then the DCE device

should support RTS flow control.)

LED’s

The RF Modem has three LED’s, Tx, Rx, and CD:

CD (Carrier Detect).

The CD LED will flash on/off for 100 mSecs when a RF connection is active. The flashing status

of CD is on a 60 Sec connection timer. After 60 Secs of inactivity the CD LED will automatically

extinguish.

The CD LED is held on when the RF Modem detects another device transmitting (receiving).

This could be its partner, another pair of RF Modems or another RF transmitting device using

the same frequency.

Tx (Transmit).

The Tx LED is illuminated when the RF Modem is currently transmitting an RF packet.

Rx (Receive).

The Rx LED is illuminated when the RF Modem detects a receive packet which is addressed to

that particular RF Modem.

POWER SUPPLY

The RF Modem requires a 9 - 12V @ 100mA power source. On the power jack the centre is +ve connection.

The power switch is a slide switch located on the bottom of the unit.

STANDBY MODE

When not transmitting, the RF Modem continually searches for a carrier signal and valid I/D address, which

match its own. When detected, the RF Modem receives the data, acknowledges back to the transmitting RF

Modem and decodes the data before transmitting it out onto the host RS232 port.

USER CONFIGURABLE JUMPER LINKS

There are several Jumper Links, which the user may set. Please note that these are only read at power up!

ECHO / REPEATER MODE (J1)

In echo mode each data packet that is received is transmitted out immediately after reception. This may be

used to extend the system range.

note: In Echo Mode, the RF Modem generates an acknowledge signal to the originating RF Modem. The

originating RF Modem will not receive an acknowledge signal from the destination RF Modem if it has been

echoed by another RF Modem.

J1

Option

Open

-

Connected

Echo Mode Selected