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Hermes Operator Note Page 28 of 32
5 HARDWARE SPECIFICATION
5.1 Introduction
The hardware of the modem part of the system is based on the FX929B
modem chip from Consumer Microcircuits Ltd (CML). The radio part of the
system can be either the G-MAX "rugged" transceiver, or the lower power
SXn50 range of transceivers. The interface between the outside world and
modem chip is controlled by a microprocessor.
The two types of transceiver are separate modules which is mounted onto
the modem PCB.
The Hermes is supplied in 2 different mechanical versions. One of these
uses a rugged enclosure suitable for wall mounting. The second version is
housed in a 3U high “euro” cassette for mounting in a standard 19" rack.
5.2 RS232 Port Parameters
The communication with the host processor is via a standard RS232 port.
The data levels are as per the RS232 specification with logic '0' being a
positive voltage.
The programmable parameters for the transmit and receive ports are:
Baud rates 4800/9600/19200/38400
Data bits 8 (note that 7data bits plus parity = 8 data bits with no
parity)
Parity Odd, Even or None
Stop bits Receiver output = 1
Input to transmitter = 1 or more