1. Communication lines

2. OSI model Open Systems Interconnection (OSI) model (ISO/IEC 7498-1) Source: homepages.uel.ac.ukhomepages.uel.ac.uk Physical layer – specifies electrical and physical properties (cable) Pins, voltages, impedance, modulation, timing, topology

3. OSI model Open Systems Interconnection (OSI) model (ISO/IEC 7498-1) Source: homepages.uel.ac.ukhomepages.uel.ac.uk Physical layer – Transmits raw bit stream over physical cable IEEE 802, RS232, RS422, RS485, I 2 C, SPI,…

4. OSI model Open Systems Interconnection (OSI) model (ISO/IEC 7498-1) Source: homepages.uel.ac.ukhomepages.uel.ac.uk Data link layer – specifies network data frame (packet), checksum, source and destination address, and data E.g. Ethernet MAC, RS232

5. OSI model Open Systems Interconnection (OSI) model (ISO/IEC 7498-1) Source: homepages.uel.ac.ukhomepages.uel.ac.uk Network layer – routing, directing datagrams from one network to another E.g. IP addresses

6. RS232 (EIA232) Dates from 1969 (RS-232-C) Last standard is TIA/EIA-232-F from 1997 Defines physical and data link layer Single transmitter and receiver TXRX Log. 0 : +5 to +15 V Log. 1 : -15 to -5 V Log. 0 : > +3 V Log. 1 : < -3 V Noise immunity: min. 2 V

7. RS232 (EIA232) Length RS-232-C = 15 m RS-232-F defines max. load capacity 2500 pF TXRX C RX ~20 pF CMCM signal shield CSCS CSCS

8. RS232 - Cable capacity C S ~ 0,5 C M unshielded cable C S ~ 2 C M shielded cable C RX ~20 pF CMCM signal shield CSCS CSCS Max. length: L max = 2500 / C total C total = C M + C S e.g. Belden 1700A TP: 78,7 Ω/km, 45,9 pF/m

9. RS232 - Communication protocol idle Log. 0 : +5 to +15 V Log. 1 : -15 to -5 V start 0 1 0 1 0 1 0 1 1 b0 b1 b2 b3 b4 b5 b6 b7 stop idle 1 (parity) Odd Even data: 11010101b (213dec) LSB MSB 1,1.5,2

10. RS232 - Asynchronous communication idle Fixed comm. speed: tx + rx same (tolerance ~3%) start 0 1 0 1 0 1 0 1 1 b0 b1 b2 b3 b4 b5 b6 b7 stop idle 1 (parity) TXRX

11. RS232 - Communication speed RS-232-F limits to 30 V/µs, max 4% of bit time => max. theoretical speed 200 kbit/s 0 11 ΔtΔt ΔVΔV

12. RS232 - Communication speed RS-232-F standard defines speeds: 50,75,110,150,300,600,1200,2400,4800,9600,19200 bit/s Common speeds above standard definition: 28800, 38400, 57600, 115200 bit/s Higher speed = lower distance Baud rate [Bd]Max length [ft]Max length [m] 19 2005015 9 600500150 4 8001 000300 2 4003 000900 source: www.hw.czwww.hw.cz

13. RS232 - Signals Dev. 1Dev. 2 TxD RxD GND RxD TxD RTS Request to send CTS Clear to send CTS RTS DTR Data terminal ready DCD Data Carrier Detect DSR Data Set Ready DTR DSR DCD

14. RS232 - Connectors source: www.arcelect.comwww.arcelect.com 9 pin

15. RS232 - Connectors source: fjkraan.home.xs4all.nlfjkraan.home.xs4all.nl 25 pin source: www.solentcables.co.ukwww.solentcables.co.uk

16. RS232 - Summary 1 transmitter, 1 receiver Common ground Typically 8 bit, no parity, 1 stop bit (8N1)

17. RS-422 (EIA-422) ANSI/TIA/EIA-422-B or ITU-T Recommendation T-REC-V.11 Uses differential signaling + GND 1 transmitter + 10 receivers 10 Mbit/s (12 m), 100 kbit/s (1200 m) Max. 1200 m Standard does not define protocol and pins

18. Differential signaling source: www.root.czwww.root.cz source: www.root.czwww.root.cz

19. RS-422 source: meteosat.pessac.free.frmeteosat.pessac.free.fr source: www.scantec.dewww.scantec.de Log. 0: V A – V B ≥ +0.2 V Log. 1: V A – V B ≤ -0.2 V

20. RS-485 ANSI/TIA/EIA-485 (1998) Uses differential signaling 32 transmitter + 32 receivers 10 Mbit/s (12 m), 100 kbit/s (1200 m) Max. 1200 m Standard does not define protocol and pins

21. RS-485 signaling Source: www.consultants-online.co.zawww.consultants-online.co.za source: www.sealevel.comwww.sealevel.com Log. 0: V A – V B ≥ +0.2 V Log. 1: V A – V B ≤ -0.2 V

22. RS-485 devices Source: www.root.czwww.root.cz Internally each node can have a transmitter and receiver, they are switched into high-impedance mode when not used

23. source: www.alciro.orgwww.alciro.org Half duplex

24. source: www.alciro.orgwww.alciro.org full duplex

25. Grounding source: hw.czhw.cz

26. Maximal speed source: hw.czhw.cz

27. RS-422 vs. RS-485 source: hw.czhw.cz

28. USB Universal serial bus (1995) Differential signaling (DATA +, DATA -) + power source: www.se7ensins.comwww.se7ensins.com source: en.wikipedia.orgen.wikipedia.org

29. USB specifications Max. 127 devices Superspeed – 5 Gbit/s (USB 3.0 - 2008) High Speed - 480Mbits/s (USB 2.0 - 1999) Full Speed - 12Mbits/s Low Speed - 1.5Mbits/s

30. USB signaling Uses NRZI (Non Return to Zero Invert) signaling host device Differential „1“: D+ greater than D- Differential „0“: D+ less than D- D+ D- Differential „1“: D+ > 2.8 V, D- < 0.3V Differential „0“: D- > 2.8 V, D+ < 0.3V

31. USB signaling source: www.tek.comwww.tek.com

32. Speed identification Full speed device source: www.beyondlogic.orgwww.beyondlogic.org

33. Speed identification Full speed device source: www.beyondlogic.orgwww.beyondlogic.org

34. Non Return to Zero Invert signaling "One" is represented by a transition of the physical level. "Zero" has no transition. source: en.wikipedia.orgen.wikipedia.org source: www.jbmelectronics.comwww.jbmelectronics.com

35. Ethernet – physical layer Standard IEEE 802.3 Max. length 100m 3 Mbit/s to 100 Gbit/s Differential signaling Signals TX+, TX-, RX+, RX- source: techpubs.sgi.comtechpubs.sgi.com

36. Ethernet – physical layer Logic levels (10BaseT - output) Log. 1 > +0.7 V Log. 0 < -0.7 V source: hw-server.comhw-server.com source: sigalrm.blogspot.comsigalrm.blogspot.com source: www.interfacebus.comwww.interfacebus.com

37. Ethernet – Manchester encoding source: en.wikipedia.orgen.wikipedia.org Encoding helps clock recovery

38. Ethernet – physical layer Ethernet data, showing MLT-3 encoding of bits. (used in e.g. 100BASE-TX) source: flickr.comflickr.com

39. Ethernet – Data Link Layer - frame synchronization source: communities.netapp.comcommunities.netapp.com

40. Ethernet – Data Link Layer - frame addresses source: communities.netapp.comcommunities.netapp.com

41. Ethernet – Data Link Layer - frame identifies what higher-level network protocol is being carried in the frame (example: TCP/IP) source: communities.netapp.comcommunities.netapp.com

42. Ethernet – Data Link Layer - frame data source: communities.netapp.comcommunities.netapp.com

43. Ethernet – Data Link Layer - frame Control checksum Cyclic redundancy check source: communities.netapp.comcommunities.netapp.com