RS232 R
ADIO
M
ODEM
1
Technical Specifications
232C-868FR1
1.1 Functional description
The RF modem is software configurable using the
standard AT command set. Commands can be entered
via the RS232 port using a control device with
communications software (for example a PC with
windows HyperTerminal). Using this method the
modem can be set to four different modes.
In transparent mode the modem provides an ‘invisible’
serial link and reproduces the function of a half duplex
RS-232 cable. Transparent secured mode operates in
the same manner of transparent mode and also
provides data flow control to ensure the correctness of
transmitted data frames. This provides the user with a
fully data verified point to point communications link.
Addressed secured mode provides a functionality
similar to that of a client/server network except that
there is no server and all of the clients can
communicate with each-other. Each modem is given an
address with a maximum of 255 clients per network and
a maximum of 65535 networks. In I/O copy mode the
four digital I/O channels can be used to transfer TTL
logic signals from one modem to another. As long as
the modem remains in I/O copy mode the signals are
automatically resent after a 1 second time-out with
ensured reliability via automatic data
acknowledgement. Detailed explanations of the
available software modes are given in section 2.
1.2 Status LED’s
The RF Modem has six LED’s, representing the following signals:
•
TxD – Transmitting data
•
RxD – Receiving data
•
CTS – Clear to send data
•
RTS – Ready to send data
•
PWR – Power on
1.3 Connections
1.3.1
Digital I/O
When used in I/O copy mode four Digital I/O signals can be presented on the 8 pin SIP header on J2, as
shown in the diagram above. Please refer to section 3.3 for control information when using the modem
in I/O copy mode.
1.3.2
Power
The RF Modem requires a 9 - 12V @ 100mA power source. On the power jack the centre is +ve
connection.
DS232-4 June ’04
©2004 Reg. No. 227 4001, ENGLAND
Page 3
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