9XTend-PKG-R RS-232/485 RF Modem User Guide
21
Operation
WARNING!
When operating at 1 Watt power output, observe a minimum separation distance of 2 m (6 ft) between
modems. Transmitting in close proximity of other modems can damage modem front ends.
Serial communications
RS-232 and RS-485/422 data flow
The XTend RS-232/422/485 RF Modem interfaces to a host device through a standard DB-9 connector. Devices that
have a standard DB-9 (RS-232) serial port can connect directly through the pins of the modem as shown in the figure
below. The following figure shows the System Data Flow in an RS-232 environment.
Host and RF Modem settings
Serial communications between a host and an XTend RF Modem are dependent upon having matching baud rate,
parity, stop bit and number of data bits settings. Failure to enter the modem into AT Command Mode is most
commonly due to baud rate mismatch. Refer to the table below to ensure host serial port settings match those of the
modem. The following table provides the Parameter Values Critical to serial communications between RF Modem and
host.
Parameter Setting
XTend RF Modem Default Parameter Value
Baud (Serial Data Rate)
9600 b/s (BD parameter = 3)
Number of Data Bits
8 (NB parameter = 0)