1. 1 Chap. 3 Interface

2. 2 Interface  Physical connection between node and transceiver  Network interface card (NIC)  Physical connection between transceivers Characteristics of Interface  Mechanical  defines cable, connector for connection  Electrical  defines voltage level, signal timing, encoding  Functional  defines function of signal line and control line (data, control, timing, grounding, etc)  Procedural  defines sequence of events via signal and control line

3. 3 RS232C  Interface standard for serial transmission regulated by EIA  3 type (A, B and C) are defined, but C version (RS232C) is widely used Mechanical spec  25pin connector and 9 pin connector Electrical spec  bipolar NRZ-L  -3V - -12V -> 1, +3V - +12V -> 0  Less than data rate of 20Kbps, shorter than transmission range of 15m

4. 4 Functional spec  GND : logical ground  TxD : transmitted data  RxD : received data

5. 5 RS422 and RS485 RS422  Differential encoding  voltage difference between two line is negative -> 1  4 line is used for full duplex (2 line for transmission, 2 line for reception)  1 driver, 32 receiver  Because data link later is not defined, additional function is developed by user RS485  Differential encoding  +-12V is used for encoding,  2 line for half duplex  1 driver, 32 receiver

6. 6 Transmission characteristics of RS422 and RS485  Distance of 1.2Km, data rate of 10Mbps SpecificationRS232CRS422RS485 voltage modesingle-endeddifferential max. number of driver/receiver 1 driver 1 receiver 1 driver 32 receivers 32 drivers 32 receivers max. distanceabout 15 mabout 1.2 km max. data rate20 Kbps10 Mbps transmission modefull duplex half duplex max. output voltage ±25V -0.25V to +6V-7V to +12V max. input voltage±15V-7V to +7V-7V to +12V

7. 7 SPI SPI (serial peripheral interface)  Defined by Motorola  4 lines for synchronous transmission (MOSI, MISO, SCK, /SS)  Data rate of several 10’s Mbps