B. Data Communications Channel
The AMD-3700 Telephonic Stethoscope data interface is in asynchronous format with:
• RS232 electrical voltage levels
• 19.2 Kb/s data rate.
• 8-bits per character.
• No Parity.
• One Stop bit.
The Data Communication Channel interface must be set up to match this specification.
The AMD-3700 Telephonic Stethoscope functions as a DTE in terms of data
communications. If the Data Channel linking the transmitting AMD-3700 unit to the
receiving AMD-3700 unit is to be a modem, multiplexer or other similar DCE, then
(probably) a straight-through cable should be used to connect the AMD-3700 units to
the Data Channel interface. The AMD-3700 unit has a male DB-9 connector at the rear
of the unit. Typically, DCE equipment will have a female DB-9 connector for its data
communications interface. In that case, a female DB-9 to male DB-9 straight through
cable should be used. Sometimes DCE equipment will have a DB-25 connector for its
interface. In that case a DB-9 to DB-25 adapter may be used, or a cable with a female
DB-9 connector at one end and a male DB-25 connector at the other end.
If a PC is used for the Data Channel interface, then it is important to know that the
Serial Port (COM Port) of a PC is a DTE interface. In that case (or any situation where
the Data Channel equipment interface is DTE), a cross-over (or null modem) cable is
needed with a female DB-9 at both ends of the cable.
Before connecting the AMD-3700 units to the Data Channel (or if data communications
problems arise), it is a good idea to test the AMD-3700 units back-to-back to verify that
they are working properly by themselves. Apply power to both AMD-3700 units and
interconnect them with a male DB-9 to male DB-9 cross-over cable as shown below.
Crossover Cable
AMD-3700
AMD-3700
AMD Global Telemedicine, Inc.
73 Princeton Street North Chelmsford, MA 01863
978-937-9021 (phone) 978-937-5249 (fax)
4
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