RS232 L
OW
C
OST
RF M
ODEM
FUNCTIONAL DESCRIPTION
FM-232C-433
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
DS232_2
June 00
©2000 Reg. No. 227 4001, ENGLAND
Page 2
RFSOLUTIONS [ RFSOLUTIONS.LTD ]
