101-1226 Rabbit Semiconductor, 101-1226 Datasheet - Page 98

• Manufacturer Part Number: 101-1226
• Description: RCM3900 DEV KIT UNIVERSAL
• Manufacturer: Rabbit Semiconductor
• Series: RabbitCore 3900r
• Type: MPU Moduler

Specifications of 101-1226

• Contents: RabbitCore Module, Dev. Board, AC Adapter, Cable and Dynamic C® CD-Rom
• For Use With/related Products: RCM3900
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 316-1137

B.4.6.2 RS-485
The Prototyping Board has one RS-485 serial channel, which is connected to the Rabbit
3000 Serial Port C through an RS-485 transceiver. The half-duplex communication uses
an output from PD7 on the Rabbit 3000 to control the transmit enable on the communica-
tion line. Using this scheme a strict master/slave relationship must exist between devices
to insure that no two devices attempt to drive the bus simultaneously.
Serial Port C is configured in software for RS-485 as follows.
The configuration shown above is based on circular buffers. RS-485 configuration may
also be done using functions from the
The Prototyping Boards with RCM3900 modules installed can be used in an RS-485 multi-
drop network spanning up to 1200 m (4000 ft), and there can be as many as 32 attached
devices. Connect the 485+ to 485+ and 485– to 485– using single twisted-pair wires as
shown in Figure B-8. Note that a common ground is recommended.
RabbitCore RCM3900 User’s Manual
#define ser485open serCopen
#define ser485close serCclose
#define ser485wrFlush serCwrFlush
#define ser485rdFlush serCrdFlush
#define ser485putc serCputc
#define ser485getc serCgetc
#define CINBUFSIZE
#define COUTBUFSIZE 15
#ifndef _485BAUD
#define _485BAUD 115200
#endif
15
Figure B-8. Multidrop Network
LIB\PACKET.LIB
library.
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