======================PROTOCOLS_RS232============================= EIA Electronics Industry Association produced standards for RS485, RS422, RS232, and RS423 previously marked with prefix "RS" to indicate recommended standard; RS232 (single-ended) introduced in 1962, allows for up to 20K bits/second to 50Ft. @ Independent channels for two-way (full-duplex) idle state (MARK) signal negative to common, active state (SPACE) signal positive to common. _______ ___ _______ ___ ___ | S | D | D | D D | D D D | D | P | T |___| |___| |___________| |___| LSB MSB S=startBit D=data P=ParityBit 1=StopBit T=1/Baud 9600Baud=104.2us RS422 (differential) pair of converters from RS232 to RS422 (and back again) can be used to form "RS232 extension cord." up to 100K bits/second up to 4000 Ft. also specified for multi-drop (party-line) SPECIFICATIONS RS232 RS423 RS422 RS485 Mode of Operation SINGLE SINGLE DIFFER- DIFFER- ENDED -ENDED ENTIAL ENTIAL Number Drivers and 1 DRIVER 1 DRIVER 1 DRIVER 1 DRIVER Receivers One Line 1 RECVR 10 RECVR 10 RECVR 32 RECVR Maximum Cable Length 50 FT. 4000 FT. 4000 FT. 4000 FT. Maximum Data Rate 20kb/s 100kb/s 10Mb/s 10Mb/s Max Driver Output -0.25V to Voltage +/-25V +/-6V +6V -7V to +12V Driver Out Loaded +/-5V to +/-3.6V +/-2.0V +/-1.5V (Loaded Min.) +/-15V Driver Unloaded +/-25V +/-6V +/-6V +/-6V Driver Load Imped 3k to 7k >=450 100 54 IoutHigh Z Pwr On N/A N/A N/A +/-100uA IoutHigh Z Pwr Off +/-6mA @ +/-100uA +/-100uA +/-100uA State +/-2v Slew Rate (Max.) 30V/uS Adjustable N/A N/A Rec Input Range +/-15V +/-12V -10V to -7V to +12V 10V Receiver Sens +/-3V +/-200mV +/-200mV +/-200mV Receiver Res 3k to 7k 4k min. 4k min. >=12k ----------------------PROTOCOLS_RS232---------------------- RS232 Common names: EIA-232D (RS232-D), ITU-TSS (CCITT) V.24/V.28, ISO 2110 [25 PIN D-SUB MALE] (at the DTE) [25 PIN D-SUB FEMALE] (at the DCE) 25 PIN D-SUB MALE at the DTE (Computer). 25 PIN D-SUB FEMALE at the DCE (Modem). Pin Name RS232 V.24 Dir Description 1 GND n/a 101 [---]Shield Ground 2 TXD BA 103 [-->]Transmit Data 3 RXD BB 104 [<--]Receive Data 4 RTS CA 105 [-->]Request to Send 5 CTS CB 106 [<--]Clear to Send 6 DSR CC 107 [<--]Data Set Ready 7 GND AB 102 [---]System Ground 8 CD CF 109 [<--]Carrier Detect 9 - - RESERVED 10 - - RESERVED 11 STF 126 [-->]Select Transmit Channel 12 S.CD SCF 122 [<--]Secondary Carrier Detect 13 S.CTS SCB 121 [<--]Secondary Clear to Send 14 S.TXD SBA 118 [-->]Secondary Transmit Data 15 TCK DB 114 [<--]Trans Signal Element Timing 16 S.RXD SBB 119 [<--]Secondary Receive Data 17 RCK DD 115 [<--]Receiver Signal Element Timing 18 LL LL 141 [-->]Local Loop Control 19 S.RTS SCA 120 [-->]Secondary Request to Send 20 DTR CD 108.2 [-->]Data Terminal Ready 21 RL RL 140 [-->]Remote Loop Control 22 RI CE 125 [<--]Ring Indicator 23 DSR CH 111 [-->]Data Signal Rate Selector 24 XCK DA 113 [-->]Transmit Signal Element Timing 25 TI TM 142 [<--]Test Indicator Note: Direction is DTE (Computer) relative DCE (Modem). Note: RS232 column is RS232 circuit name. Note: ITU-T column is ITU-TSS V.24 circuit name. Note: Do not connect SHIELD(1) to GND(7). start bit requires gate senses falling edge during clock high. stop bit set to detect a rising edge. Usually customer has option of setting the lower 3 address bits externally. But this requires pins. ViH_min = 3V ViL_max = 1.5 at 5VCC min low time = 4.17uS min high time is 4us start data high = bus free max bus cap 400pf = 100kbits/sec less tan 10k ohms http://wombat.doc.ic.ac.uk/foldoc/index.html flow control stop sending data When buffer at "high water mark" resume at "low water mark" escape sequence ("escape code") (ASCII 27) from DEC vt100 video terminal perform special function , Hayes modem uses "+++" Device Control four ASCII characters, DC1, DC2, DC3, and DC4, once used to remotely control equipment paired,DC1/DC3 turning one device on/off,DC2/DC4 another null modem RS-232 cable, for two computers directly both computers transmit pin three and recieve pin two, It also needs male connectors at both ends to spec . TXD:Transmit data RXD:Receive data RTS:Request to send (Pc sets this when ready to send ) CTS:Clear to send (modem ready to transmit ) DTR:Data terminalready (PC tells modem ready to send ) DSR:Data set ready (modem tells PC ready to transmit) CD:Carrier detect (modem sets this when detects PC) DTE:Data Terminal Equipment (terminal) DCE:Data Circuit-terminating Equipment (modem,computer) _______ ___ _______ ___ ___ | S | D | D | D D | D D D | D | P | T |___| |___| |___________| |___| LSB MSB S=startBit D=data P=ParityBit 1=StopBit T=1/Baud 9600Baud=104.2us _________ RS232C DB25 Male | | \ \ |13_| \ \ | ()_) _\ \ 13 Clear2 Send2 |12_|()_)|25 | 25 Test Mode | ()_) _ | | 12 SignalDetect2 |11_|()_)|24 | 24 DTE source | ()_) _ | | |10_|()_)|23 | 23 Data signal Rate | ()_) _ | | | _|()_)|22 | 22 Ring Indicator |9()_) | | | _|()_)|21 | 21 Remote loop back |8()_) _ | | 8 CD CarrierDetect CD or DCD | _|()_)|20 | 20 DTR Data Termin ready DTE or DTR |7()_) _ | | 7 GND Signal Gnd | _|()_)|19 | 19 Request to Send2 |6()_) | | 6 DSR Dataset Ready MAC =5V | _|()_)|18 | 18 Local loop back |5()_) _ | | 5 CTS Clear to Send | _|()_)|17 | 17 DCE source(rec signtiming) |4()_) _ | | 4 Request2 Send | _|()_)|16 | 16 Receive Data2 |3()_) | | 3 RXD Receive Data | _|()_)|15 | 15 DCE source(xtm sig timing) |2()_) _ | | 2 Transmit Data | _|()_)|14 | 14 TXD Transmit Data2 |1()_) / / 1 GND Shield GND | | / / |___|_/___/ _________ RS232C DB25 FeMale | \ \ | \ \ |1() \ \ 1 GND Shield | () |14 | 14 RXD Receive Data2 ->TXD |2() | | 2 Receive Data | () |15 | 15 DCE source(xtm sig timing |3() | | 3 TXD Transmit Data ->RXD | () |16 | 16 Transmit Data2 |4() | | 4 CTS Clear to Send | () |17 | 17 DCE source(rec sign timing |5() | | 5 RTS Request2 Send | () |18 | 18 Local loop back |6() | | 6 Dataset Ready | () |19 | 19 Clear to Send2 |7() | | 7 GND Signal Gnd | () |20 | 20 DTE Rdy (Data Termin Equip) |8() | | 8 Receive Line Signal Detect | () |21 | 21 Remote loop back |9() | | | () |22 | 22 Ring Indicator | () | | |10 () |23 | 23 Data signal Rate | () | | |11 () |24 | 24 DTE source | () | | 12 SignalDetect2 |12 () |25 | 25 Test Mode | () / / 13 Request2Send2 |13 / / |_____/___/ RTS: Request to send CTS: Clear to send DTR: Data terminalready compsets high = ready to transmit DSR: Data set ready modem sets high = ready DCD: Data Carrier detect modem sets high = detect a carrier _________ Mac_2_RS232_printer | | \ \ |13_| \ \ | ()_) _\ \ |12_|()_)|25 | | ()_) _ | | |11_|()_)|24 | | ()_) _ | | |10_|()_)|23 | | ()_) _ | | | _|()_)|22 | |9()_) | | | _|()_)|21 | |8()_) _ | | | _|()_)|20 | |7()_) _ | | 7 Signal Gnd | _|()_)|19 | |6()_) | | 6 DSR MAC =5V | _|()_)|18 | |5()_) _ | | | _|()_)|17 | |4()_) _ | | | _|()_)|16 | |3()_) | | 3 Receive Data | _|()_)|15 | |2()_) _ | | 2 Transmit Data | _|()_)|14 | |1()_) / / 1 Shield GND | | / / |___|_/___/ _________ | | \ \ RS232C DB9 Male | _| \ \ |5()_) _\ \ 5 TXD ->RXD | _|()_)|9 | 9 RXD ->TXD |4()_) _ | | | _|()_)|8 | 9 -> p8 |3()_) _ | | 3 GND | _|()_)|7 | 7 -> p7 |2()_) _ | | 2 +5V | _|()_)|6 | 6 +12 DTR -> p8 |1()_) / / | | / / |___|_/___/ DTE DCE TX ____ ____ TX | | RV ___/|\__| __ RV |_____| RTS ___ ____ RTS | | CTS___/|\__| __ CTS |_____| GND _____________ GND Mac_2_Modem _________ | | \ \ RS232C DB9 Male | _| \ \ |5()_) _\ \ 5 TXD ->RXD | _|()_)|9 | 9 RXD ->TXD |4()_) _ | | | _|()_)|8 | 9 -> p8 |3()_) _ | | 3 GND | _|()_)|7 | 7 -> p7 |2()_) _ | | 2 +5V | _|()_)|6 | 6 +12 DTR -> p8 |1()_) / / | | / / |___|_/___/ _________ | | \ \ RS232C DB9 Male | _| \ \ |5()_) _\ \ 5 TXD ->RXD | _|()_)|9 | 9 RXD ->TXD |4()_) _ | | | _|()_)|8 | 9 -> p8 |3()_) _ | | 3 GND | _|()_)|7 | 7 -> p7 |2()_) _ | | 2 +5V | _|()_)|6 | 6 +12 DTR -> p8 |1()_) / / | | / / |___|_/___/ RS232_Reversal TX ____ ____ TX | | RV ___/|\__| __ RV |_____| DTR ____________ DTR RTS ___ | CTS____|________ DCD DCD ___ ____ RTS | | DSR___/|\__| __ DSR |_____| RTS: Request to send CTS: Clear to send DTR: Data terminalready DSR: Data set ready _________ RS232C DB9 Male | | \ \ | _| \ \ |5()_) _\ \ 5 GND Signal Gnd | _|()_)|9 | 9 Ring Indicator |4()_) _ | | 4 DTE | _|()_)|8 | 8 CTS Clear to Send |3()_) | | 3 TXD Transmit Data | _|()_)|7 | 7 RTS Request to Send |2()_) _ | | 2 RXD Receive Data | _|()_)|6 | 6 DCE Ready |1()_) / / 1 CD Carrier signal detect | | / / |___|_/___/ ________ | \ \ RS232C DB9 FeMale | \ \ |1() \ \ 1 CD | ()6 | | 6 DSR |2() | | 2 RXD | ()7 | | 7 RTS |3() | | 3 TXD | ()8 | | 8 CTS |4() | | 4 DTR | ()9 | | 9 Ring Indicator |5() / / 5 Gnd signal Gnd | / / |_____/__/ Gender_Change ________ | \ \ RS232C DB9 FeMale | \ \ |1() \ \ 1 CD | ()6 | | 6 DSR |2() | | 2 RXD | ()7 | | 7 RTS |3() | | 3 TXD | ()8 | | 8 CTS |4() | | 4 DTR | ()9 | | 9 Ring Indicator |5() / / 5 Gnd signal Gnd | / / |_____/__/ ________ | \ \ RS232C DB9 FeMale | \ \ |1() \ \ 1 CD | ()6 | | 6 DSR |2() | | 2 RXD | ()7 | | 7 RTS |3() | | 3 TXD | ()8 | | 8 CTS |4() | | 4 DTR | ()9 | | 9 Ring Indicator |5() / / 5 Gnd signal Gnd | / / |_____/__/ ________ COPS | \ \ RS232C DB9 FeMale port | \ \ |1() \ \ | ()6 | | |2() | | 2 RXD | ()7 | | 7 RTS |3() | | 3 TXD | ()8 | | 8 CTS |4() | | | ()9 | | |5() / / 5 Signal Gnd | / / |_____/__/ ________ CABLE_COPS | \ \ RS232C DB9 FeMale | \ \ |1() \ \ 1 CD | ()6 | | 6 DSR |2() | | 2 RXD | ()7 | | 7 RTS |3() | | 3 TXD | ()8 | | 8 CTS |4() | | 4 DTR | ()9 | | 9 Ring Indicator |5() / / 5 Gnd | / / |_____/__/ _________ | | \ \ RS232C DB9 Male | _| \ \ |5()_) _\ \ 5 Signal Gnd | _|()_)|9 | 9 Ring Indicator |4()_) _ | | 4 DTE Rdy | _|()_)|8 | 8 Clear to Send |3()_) | | 3 Transmit Data | _|()_)|7 | 7 Request to Send |2()_) _ | | 2 Receive Data | _|()_)|6 | 6 DCE Ready |1()_) / / 1 Receive Line | | / / Signal Detect |___|_/___/ ________ CABLE1_mac | \ \ RS232C DB9 FeMale | \ \ |1() \ \ | ()6 | | |2() | | 2 is open | ()7 | | |3() | | | ()8 | | |4() | | | ()9 | | |5() / / | / / |_____/__/ ____ ____ / V \ Male / 4 0 8 \ / \ | 5 1,3 9 | | | \_ 6 7 _/ |_______| _________ CABLE2_mac | | \ \ RS232C DB9 Male | _| \ \ |5()_) _\ \ 5 Signal Gnd | _|()_)|9 | 9 Ring Indicator |4()_) _ | | 4 DTE Rdy | _|()_)|8 | 8 Clear to Send |3()_) _ | | 3 Transmit Data | _|()_)|7 | 7 Request to Send |2()_) _ | | 2 Receive Data | _|()_)|6 | 6 DCE Ready |1()_) / / 1 Receive Line | | / / |___|_/___/ ____ ____ / V \ Male / 8 7 4 \ / gnd \ | 9 1gnd 5 | | tx rx | \_ 7 6 _/ |_______| rts cts _________ RS232C DB9 Male | | \ \ | _| \ \ |5()_) _\ \ 5 Signal Gnd | _|()_)|9 | 9 Ring Indicator |4()_) _ | | 4 DTE Rdy | _|()_)|8 | 8 Clear to Send |3()_) _ | | 3 Transmit Data | _|()_)|7 | 7 Request to Send |2()_) _ | | 2 Receive Data | _|()_)|6 | 6 DCE Ready |1()_) / / 1 Receive Line | | / / |___|_/___/ ____ ____ / V \ FeMale / 0 - 5 \ / \ | 7 1 5 | | | \_ 3 2 _/ |_______| Blue Orange Red Yellow ____ ____ / V \ Male / R _ 5 \ / | | \ | O |_| B | | | \_ Y 2 _/ |_______| HX20_2_RS232-------------------------- _________ / _ TXD \ Cable _/ 2()_) _ \ CTS 5()_) _ 4()_) \ RTS _| ()_) _ | RXD 3()_) 6 1()_) | GND \_ DSR _ / DCD 8()_) 7()_) / DTR \________/ T? = Transmit? = DTR H! = Hold! = CTS shorted to RTS _________ | | \ \ RS232C DB9 Male | _| \ \ TXD->RXD |5()_) _\ \ | _|()_)|9 | RXD->TXD |4()_) _ | | | _|()_)|8 | GND |3()_) _ | | | _|()_)|7 | T? -> H! +5V |2()_) _ | | | _|()_)|6 | H! -> T? |1()_) / / | | / / |___|_/___/ TX ____ ____ TX | | RV ___/|\__| __ RV |_____| DTR ____________ DTR RTS ___ | CTS____|________ DCD DCD ___ ____ RTS | | DSR___/|\__| __ DSR |_____| RTS: Request to send CTS: Clear to send DTR: Data terminalready DSR: Data set ready _________ HX20 port / TXD \ HX20_2_RS232 / 2() \ RTS /4() 5()\ CTS | () | GND |1() 6 3()| RXD \ DSR / DTR \ 7() 8() /DCD \____^____/ Request to send RTS: high trans, high or low receive Clear to send CTS: must be high to trans.. norm = don't care Data terminalready DTR: must be high to tramsmit Data set ready DSR: Send out when ready to transmit Data Carrier detect DCD: High all the time HX20 port _________ / _ TXD \ ->p3_d25_RXD _/ 2()_) _ \ CTS->p8_d25_DCD 5()_) _ 4()_) \ RTS ->p8_d25_DCD _| ()_) _ | RXD->p2_d25_TXD 3()_) 6 1()_) | GND ->p7_d25_GND \_ DSR _ / DCD->p6_d25_DSR 8()_) ^ 7()_) /DTR ->p20_d25_DTR \_|______/ CTS shorted to RTS |__ ->p4_d25_RTS D-type connector so named because one side is shorter (with one less pin) (squarish) "D" shape.25-way(13+12 pins) a9-way(5+4 pins) UART Universal Asynchronous Receiver/Transmitter a transmitter (parallel-to-serial converter) a receiver each clocked separately. parallel side of a UART isconnected to bus of computer. computer writes to UART's transmit data register (TDR), UART start transmit on the serial line. UART's status register flag bit if ready for another byte. Another status register bit says UART has received a byte computer read it from receive data register (RDR). If another byte received before previous one read, UART signal an "overrun" error via another status bit. The UART set up to interrupt the computer format the UART by the UART's control register incorrectly formated signal "framing/"parity error". Often the clock will run at 16 times the baud rate to read each bit in middle of its allotted time period makes the UART more tolerant to "jitter" stop bit extra "1" bits which follow the data and any parity bit. mark end of a byte or character). start bit signals the start of transmission oon a serial line zero-one transition tells receiver when to start sampling the signal to extract the data bits. synchronous Two or more processes common timing signals. asynchronous Not synchronised by shared clock , execution independently loser An unexpectedly bad situation, program,programmer Someone who habitually loses. (Even winners can lose ) Someone who knows not and knows not that he knows not. Emphatic forms real loser,total loser,complete loser" (not "moby loser", which is a contradiction in terms). RS-232C The EIA RS-232C electrical signal unbalanced +/- 5 to +/- 12V, polar non return to zero speeds up to 19.2 kilobits per second. DTE Data Terminal Equipment controls communication channel (terminals, computers) DCE Data Communication Equipment ...typically a modem IF "straight-through" cable (p1 to p1, p2 to p2 etc.) DTE should a male connector + trans on p3 and rece p2. gender mender gender bender,gender blender,sex changer,homosexualadaptor two male/female connectors used to correct mismatch RS-232 Originally DCE was modem and DTE was computer/terminal DCE RS-232 have female connector and tran p2 and rec p3 DTE RS-232 have male connector and tran p3 and rec p2 http://wombat.doc.ic.ac.uk/foldoc/ foldoc.cgi?hardware+handshaking TX ____ ____ TX | | RV ___/|\__| __ RV |_____| GND _____________ GND DTE DCE DTE: Data Terminal Equipment (terminal) DCE: Data Circuit-terminating Equipment (modem,computer) RS232C Max 20Kbps @ 15meters unbalanced Logic_0 "space" Vout +3V -> +15B Logic_1 "mark" Vout -3V -> -15V RS422 twisted pair balanced 10Mbps @ 12 meters .1Mbps@1.2Km _______ ___ _______ ___ ___ | S | D | D | D D | D D D | D | P | T |___| |___| |___________| |___| LSB MSB S=startBit D=data P=ParityBit 1=StopBit T=1/Baud 9600Baud=104.2us DTE Rdy Trans Recv Sig Det _ ___ _______ ___ _________ | ST| D0| D1| D2 D2| D4 D5 D6| D7| P | SB| : |___| |___| |___________| |___| | LSB MSB startBit ST data D ParityBit P StopBit 1 T 1/Baud 9600Baud= 104.2us Software Handshake XON and XOFF Hardware DTE DCE TX ____ ____ TX | | RV ___/|\__| __ RV |_____| RTS ___ ____ RTS | | CTS___/|\__| __ CTS |_____| GND _____________ GND RTS: Request to send CTS: Clear to send DTR: Data terminalready compu sets space_Hi so printer recev DSR: Data set ready printer sets space_Hi to receive DCD: Data carrier detect must space_Hi for printer to receiv n=0 is Speaker always off, n=0 is Speaker always on, n=1 is Speaker on until carrier detected (default) n=3 is Speaker on after dial through CONNECT O Return to on-line state P Pulse Dial Qn n=0 is send Resun Codes, n-1 is do not send code R Reverse mode (Originate Only) S0=n n=0 to 255 rings before answer (sees switch 5) S1=n n=0 to 127, count rings S2=n n=0 to 127, 43 default , Set escape code character S3=n n=0 to 127, 13 default , Set cr character S4=n n=0 to 127, 10 default, Set Line Feed character S5=n n=0 to 127, 8 default, Set Backspace character S6=n n=2 to 255, Wait for dial tone seconds S7=n n=2 to 255, Wait carrier detect seconds S8=n n=0 to 255, Set duration pause seconds S9=n Carrier detect response time seconds/10 S1O=n Delay time carrier loss to hang-up 1/10sec. Sll=n Duration a ndspace of Touch Tones ( 50ms to 255ms) S12=n Escape code guard time 1-255 1/10 sec S13=n UART status bit map (reserved) S14-n Option Register, product code returned by AT10 S15=n Flag Register(reserved) S16=n Self test mod�. n=O is data mode (default), n-1 is Analog Loopback, n=2 is dial test n=4 is Test Pattern, n=5 is Analog Loopback and Test Pattern. Sn? Send contents of Register n (0 to 16) to Computer T Touch Tone Dial Vn n-O is send resun�u�eo�d�d�B��-1 is wMds Xn n-B send basic result code 1 to 8 send extended resun codes B to 12 Z Somvare reset and reset to defaun values Hardware DTE DCE TX ____ ____ TX | | RV ___/|\__| __ RV |_____| RTS ___ ____ RTS ??????????? | | CTS___/|\__| __ CTS |_____| DTR ___ ____ DTR | | DSR___/|\__| __ DSR |_____| GND _____________ GND RTS: Request to send CTS: Clear to send DTR: Data terminalready DSR: Data set ready TXD: Transmit data RXD: Receive data RTS: Request to send (Pc sets this when ready to send ) CTS: Clear to send (modem ready to transmit ) DTR: Data terminalready (PC tells modem ready to send ) DSR: Data set ready (modem tells PC ready to transmit) CD: Carrier detect (modem sets this when detects PC) DTE: Data Terminal Equipment (terminal) DCE: Data Circuit-terminating Equipment (modem,computer) Half_dulplex data sent only in one direction at a time Full_dulplex data sent in both directions at a time Synchronous transmit data in blocks using sync characters 1baud one audio signal transitions per second FSK: Frequency_shift_Keying logic_0 = 1080Hz Logic_1 = 1750Hz 1baud =1bps PSK: Phase_shift_Keying logic_1/0 set by alternating carrier phase more bits per baud since phases are 0,90,180,270 QAM: Quadrature)_amplitude_modulation Both phase and frequency 1.7KHz or1.8Khz @ 2400baud only 4 bits usable per baud TCM: TCQAM or Trellic_coded quadrature_amplitude_modulation 6bits per baud. 14,400 bps modems use this CCITT V.XX Standards Consultative Committee InternalTelepho&Telegraph V.22 synch/asynch ,full duplex,2 wires, 1200bpsdata V.22bis synch/asynch ,full duplex,2 wires, 2400/1200bpsdata V.32 synch/asynch ,full duplex,2 wires, 9600bpsdata V.32bis synchs/asynch,full dupx,2wires,4.8K,7.2K,9.6K,12K,14.4Kbps V.34bis synchs/asynch,full dupx,2wires,28.8Kbps,speed<=line noise V.35 synchs/asynch ,full duplex,2 wires Bell stand : 0.3K,1.2K,2.4K,4.8Kbps TXD: Transmit data RXD: Receive data RTS: Request to send (Pc sets high when ready to send ) CTS: Clear to send (modem ready to transmit ) DTR: Data terminalready (PC tells modem ready to send ) DSR: Data set ready (modem tells PC ready to transmit) CD: Carrier detect (modem sets this when detects PC) DTE: Data Terminal Equipment (terminal) DCE: Data Circuit-terminating Equipment (modem,computer) ASCII American Standard Code for Information Interchange US-ASCII uses lower seven bits (character points 0 to 127) RS232 Common names: EIA-232D (RS232-D), ITU-TSS (CCITT) V.24/V.28, ISO 2110 [25 PIN D-SUB MALE] (at the DTE) [25 PIN D-SUB FEMALE] (at the DCE) 25 PIN D-SUB MALE at the DTE (Computer). 25 PIN D-SUB FEMALE at the DCE (Modem). Pin Name RS232 V.24 Dir Description 1 GND n/a 101 [---]Shield Ground 2 TXD BA 103 [-->]Transmit Data 3 RXD BB 104 [<--]Receive Data 4 RTS CA 105 [-->]Request to Send 5 CTS CB 106 [<--]Clear to Send 6 DSR CC 107 [<--]Data Set Ready 7 GND AB 102 [---]System Ground 8 CD CF 109 [<--]Carrier Detect 9 - - RESERVED 10 - - RESERVED 11 STF 126 [-->]Select Transmit Channel 12 S.CD SCF 122 [<--]Secondary Carrier Detect 13 S.CTS SCB 121 [<--]Secondary Clear to Send 14 S.TXD SBA 118 [-->]Secondary Transmit Data 15 TCK DB 114 [<--]Trans Signal Element Timing 16 S.RXD SBB 119 [<--]Secondary Receive Data 17 RCK DD 115 [<--]Receiver Signal Element Timing 18 LL LL 141 [-->]Local Loop Control 19 S.RTS SCA 120 [-->]Secondary Request to Send 20 DTR CD 108.2 [-->]Data Terminal Ready 21 RL RL 140 [-->]Remote Loop Control 22 RI CE 125 [<--]Ring Indicator 23 DSR CH 111 [-->]Data Signal Rate Selector 24 XCK DA 113 [-->]Transmit Signal Element Timing 25 TI TM 142 [<--]Test Indicator Note: Direction is DTE (Computer) relative DCE (Modem). Note: RS232 column is RS232 circuit name. Note: ITU-T column is ITU-TSS V.24 circuit name. Note: Do not connect SHIELD(1) to GND(7). start bit requires gate senses falling edge during clock high. stop bit set to detect a rising edge. Usually customer has option of setting the lower 3 address bits externally. But this requires pins. ViH_min = 3V ViL_max = 1.5 at 5VCC min low time = 4.17uS min high time is 4us start data high = bus free max bus cap 400pf = 100kbits/sec less tan 10k ohms http://wombat.doc.ic.ac.uk/foldoc/index.html flow control stop sending data When buffer at "high water mark" resume at "low water mark" escape sequence ("escape code") (ASCII 27) from DEC vt100 video terminal perform special function , Hayes modem uses "+++" Device Control four ASCII characters, DC1, DC2, DC3, and DC4, once used to remotely control equipment paired,DC1/DC3 turning one device on/off,DC2/DC4 another null modem RS-232 cable, for two computers directly both computers transmit pin three and recieve pin two, It also needs male connectors at both ends to spec . TXD:Transmit data RXD:Receive data RTS:Request to send (Pc sets this when ready to send ) CTS:Clear to send (modem ready to transmit ) DTR:Data terminalready (PC tells modem ready to send ) DSR:Data set ready (modem tells PC ready to transmit) CD:Carrier detect (modem sets this when detects PC) DTE:Data Terminal Equipment (terminal) DCE:Data Circuit-terminating Equipment (modem,computer) _______ ___ _______ ___ ___ | S | D | D | D D | D D D | D | P | T |___| |___| |___________| |___| LSB MSB S=startBit D=data P=ParityBit 1=StopBit T=1/Baud 9600Baud=104.2us _________ RS232C DB25 Male | | \ \ |13_| \ \ | ()_) _\ \ 13 Clear2 Send2 |12_|()_)|25 | 25 Test Mode | ()_) _ | | 12 SignalDetect2 |11_|()_)|24 | 24 DTE source | ()_) _ | | |10_|()_)|23 | 23 Data signal Rate | ()_) _ | | | _|()_)|22 | 22 Ring Indicator |9()_) | | | _|()_)|21 | 21 Remote loop back |8()_) _ | | 8 CD CarrierDetect CD or DCD | _|()_)|20 | 20 DTR Data Termin ready DTE or DTR |7()_) _ | | 7 GND Signal Gnd | _|()_)|19 | 19 Request to Send2 |6()_) | | 6 DSR Dataset Ready MAC =5V | _|()_)|18 | 18 Local loop back |5()_) _ | | 5 CTS Clear to Send | _|()_)|17 | 17 DCE source(rec signtiming) |4()_) _ | | 4 Request2 Send | _|()_)|16 | 16 Receive Data2 |3()_) | | 3 RXD Receive Data | _|()_)|15 | 15 DCE source(xtm sig timing) |2()_) _ | | 2 Transmit Data | _|()_)|14 | 14 TXD Transmit Data2 |1()_) / / 1 GND Shield GND | | / / |___|_/___/ _________ RS232C DB25 FeMale | \ \ | \ \ |1() \ \ 1 GND Shield | () |14 | 14 RXD Receive Data2 ->TXD |2() | | 2 Receive Data | () |15 | 15 DCE source(xtm sig timing |3() | | 3 TXD Transmit Data ->RXD | () |16 | 16 Transmit Data2 |4() | | 4 CTS Clear to Send | () |17 | 17 DCE source(rec sign timing |5() | | 5 RTS Request2 Send | () |18 | 18 Local loop back |6() | | 6 Dataset Ready | () |19 | 19 Clear to Send2 |7() | | 7 GND Signal Gnd | () |20 | 20 DTE Rdy (Data Termin Equip) |8() | | 8 Receive Line Signal Detect | () |21 | 21 Remote loop back |9() | | | () |22 | 22 Ring Indicator | () | | |10 () |23 | 23 Data signal Rate | () | | |11 () |24 | 24 DTE source | () | | 12 SignalDetect2 |12 () |25 | 25 Test Mode | () / / 13 Request2Send2 |13 / / |_____/___/ RTS: Request to send CTS: Clear to send DTR: Data terminalready compsets high = ready to transmit DSR: Data set ready modem sets high = ready DCD: Data Carrier detect modem sets high = detect a carrier _________ Mac_2_RS232_printer | | \ \ |13_| \ \ | ()_) _\ \ |12_|()_)|25 | | ()_) _ | | |11_|()_)|24 | | ()_) _ | | |10_|()_)|23 | | ()_) _ | | | _|()_)|22 | |9()_) | | | _|()_)|21 | |8()_) _ | | | _|()_)|20 | |7()_) _ | | 7 Signal Gnd | _|()_)|19 | |6()_) | | 6 DSR MAC =5V | _|()_)|18 | |5()_) _ | | | _|()_)|17 | |4()_) _ | | | _|()_)|16 | |3()_) | | 3 Receive Data | _|()_)|15 | |2()_) _ | | 2 Transmit Data | _|()_)|14 | |1()_) / / 1 Shield GND | | / / |___|_/___/ _________ | | \ \ RS232C DB9 Male | _| \ \ |5()_) _\ \ 5 TXD ->RXD | _|()_)|9 | 9 RXD ->TXD |4()_) _ | | | _|()_)|8 | 9 -> p8 |3()_) _ | | 3 GND | _|()_)|7 | 7 -> p7 |2()_) _ | | 2 +5V | _|()_)|6 | 6 +12 DTR -> p8 |1()_) / / | | / / |___|_/___/ DTE DCE TX ____ ____ TX | | RV ___/|\__| __ RV |_____| RTS ___ ____ RTS | | CTS___/|\__| __ CTS |_____| GND _____________ GND Mac_2_Modem _________ | | \ \ RS232C DB9 Male | _| \ \ |5()_) _\ \ 5 TXD ->RXD | _|()_)|9 | 9 RXD ->TXD |4()_) _ | | | _|()_)|8 | 9 -> p8 |3()_) _ | | 3 GND | _|()_)|7 | 7 -> p7 |2()_) _ | | 2 +5V | _|()_)|6 | 6 +12 DTR -> p8 |1()_) / / | | / / |___|_/___/ _________ | | \ \ RS232C DB9 Male | _| \ \ |5()_) _\ \ 5 TXD ->RXD | _|()_)|9 | 9 RXD ->TXD |4()_) _ | | | _|()_)|8 | 9 -> p8 |3()_) _ | | 3 GND | _|()_)|7 | 7 -> p7 |2()_) _ | | 2 +5V | _|()_)|6 | 6 +12 DTR -> p8 |1()_) / / | | / / |___|_/___/ RS232_Reversal TX ____ ____ TX | | RV ___/|\__| __ RV |_____| DTR ____________ DTR RTS ___ | CTS____|________ DCD DCD ___ ____ RTS | | DSR___/|\__| __ DSR |_____| RTS: Request to send CTS: Clear to send DTR: Data terminalready DSR: Data set ready _________ RS232C DB9 Male | | \ \ | _| \ \ |5()_) _\ \ 5 GND Signal Gnd | _|()_)|9 | 9 Ring Indicator |4()_) _ | | 4 DTE | _|()_)|8 | 8 CTS Clear to Send |3()_) | | 3 TXD Transmit Data | _|()_)|7 | 7 RTS Request to Send |2()_) _ | | 2 RXD Receive Data | _|()_)|6 | 6 DCE Ready |1()_) / / 1 CD Carrier signal detect | | / / |___|_/___/ ________ | \ \ RS232C DB9 FeMale | \ \ |1() \ \ 1 CD | ()6 | | 6 DSR |2() | | 2 RXD | ()7 | | 7 RTS |3() | | 3 TXD | ()8 | | 8 CTS |4() | | 4 DTR | ()9 | | 9 Ring Indicator |5() / / 5 Gnd signal Gnd | / / |_____/__/ Gender_Change ________ | \ \ RS232C DB9 FeMale | \ \ |1() \ \ 1 CD | ()6 | | 6 DSR |2() | | 2 RXD | ()7 | | 7 RTS |3() | | 3 TXD | ()8 | | 8 CTS |4() | | 4 DTR | ()9 | | 9 Ring Indicator |5() / / 5 Gnd signal Gnd | / / |_____/__/ ________ | \ \ RS232C DB9 FeMale | \ \ |1() \ \ 1 CD | ()6 | | 6 DSR |2() | | 2 RXD | ()7 | | 7 RTS |3() | | 3 TXD | ()8 | | 8 CTS |4() | | 4 DTR | ()9 | | 9 Ring Indicator |5() / / 5 Gnd signal Gnd | / / |_____/__/ ________ COPS | \ \ RS232C DB9 FeMale port | \ \ |1() \ \ | ()6 | | |2() | | 2 RXD | ()7 | | 7 RTS |3() | | 3 TXD | ()8 | | 8 CTS |4() | | | ()9 | | |5() / / 5 Signal Gnd | / / |_____/__/ ________ CABLE_COPS | \ \ RS232C DB9 FeMale | \ \ |1() \ \ 1 CD | ()6 | | 6 DSR |2() | | 2 RXD | ()7 | | 7 RTS |3() | | 3 TXD | ()8 | | 8 CTS |4() | | 4 DTR | ()9 | | 9 Ring Indicator |5() / / 5 Gnd | / / |_____/__/ _________ | | \ \ RS232C DB9 Male | _| \ \ |5()_) _\ \ 5 Signal Gnd | _|()_)|9 | 9 Ring Indicator |4()_) _ | | 4 DTE Rdy | _|()_)|8 | 8 Clear to Send |3()_) | | 3 Transmit Data | _|()_)|7 | 7 Request to Send |2()_) _ | | 2 Receive Data | _|()_)|6 | 6 DCE Ready |1()_) / / 1 Receive Line | | / / Signal Detect |___|_/___/ ________ CABLE1_mac | \ \ RS232C DB9 FeMale | \ \ |1() \ \ | ()6 | | |2() | | 2 is open | ()7 | | |3() | | | ()8 | | |4() | | | ()9 | | |5() / / | / / |_____/__/ ____ ____ / V \ Male / 4 0 8 \ / \ | 5 1,3 9 | | | \_ 6 7 _/ |_______| _________ CABLE2_mac | | \ \ RS232C DB9 Male | _| \ \ |5()_) _\ \ 5 Signal Gnd | _|()_)|9 | 9 Ring Indicator |4()_) _ | | 4 DTE Rdy | _|()_)|8 | 8 Clear to Send |3()_) _ | | 3 Transmit Data | _|()_)|7 | 7 Request to Send |2()_) _ | | 2 Receive Data | _|()_)|6 | 6 DCE Ready |1()_) / / 1 Receive Line | | / / |___|_/___/ ____ ____ / V \ Male / 8 7 4 \ / gnd \ | 9 1gnd 5 | | tx rx | \_ 7 6 _/ |_______| rts cts _________ RS232C DB9 Male | | \ \ | _| \ \ |5()_) _\ \ 5 Signal Gnd | _|()_)|9 | 9 Ring Indicator |4()_) _ | | 4 DTE Rdy | _|()_)|8 | 8 Clear to Send |3()_) _ | | 3 Transmit Data | _|()_)|7 | 7 Request to Send |2()_) _ | | 2 Receive Data | _|()_)|6 | 6 DCE Ready |1()_) / / 1 Receive Line | | / / |___|_/___/ ____ ____ / V \ FeMale / 0 - 5 \ / \ | 7 1 5 | | | \_ 3 2 _/ |_______| Blue Orange Red Yellow ____ ____ / V \ Male / R _ 5 \ / | | \ | O |_| B | | | \_ Y 2 _/ |_______| HX20_2_RS232-------------------------- _________ / _ TXD \ Cable _/ 2()_) _ \ CTS 5()_) _ 4()_) \ RTS _| ()_) _ | RXD 3()_) 6 1()_) | GND \_ DSR _ / DCD 8()_) 7()_) / DTR \________/ T? = Transmit? = DTR H! = Hold! = CTS shorted to RTS _________ | | \ \ RS232C DB9 Male | _| \ \ TXD->RXD |5()_) _\ \ | _|()_)|9 | RXD->TXD |4()_) _ | | | _|()_)|8 | GND |3()_) _ | | | _|()_)|7 | T? -> H! +5V |2()_) _ | | | _|()_)|6 | H! -> T? |1()_) / / | | / / |___|_/___/ TX ____ ____ TX | | RV ___/|\__| __ RV |_____| DTR ____________ DTR RTS ___ | CTS____|________ DCD DCD ___ ____ RTS | | DSR___/|\__| __ DSR |_____| RTS: Request to send CTS: Clear to send DTR: Data terminalready DSR: Data set ready _________ HX20 port / TXD \ HX20_2_RS232 / 2() \ RTS /4() 5()\ CTS | () | GND |1() 6 3()| RXD \ DSR / DTR \ 7() 8() /DCD \____^____/ Request to send RTS: high trans, high or low receive Clear to send CTS: must be high to trans.. norm = don't care Data terminalready DTR: must be high to tramsmit Data set ready DSR: Send out when ready to transmit Data Carrier detect DCD: High all the time HX20 port _________ / _ TXD \ ->p3_d25_RXD _/ 2()_) _ \ CTS->p8_d25_DCD 5()_) _ 4()_) \ RTS ->p8_d25_DCD _| ()_) _ | RXD->p2_d25_TXD 3()_) 6 1()_) | GND ->p7_d25_GND \_ DSR _ / DCD->p6_d25_DSR 8()_) ^ 7()_) /DTR ->p20_d25_DTR \_|______/ CTS shorted to RTS |__ ->p4_d25_RTS D-type connector so named because one side is shorter (with one less pin) (squarish) "D" shape.25-way(13+12 pins) a9-way(5+4 pins) UART Universal Asynchronous Receiver/Transmitter a transmitter (parallel-to-serial converter) a receiver each clocked separately. parallel side of a UART isconnected to bus of computer. computer writes to UART's transmit data register (TDR), UART start transmit on the serial line. UART's status register flag bit if ready for another byte. Another status register bit says UART has received a byte computer read it from receive data register (RDR). If another byte received before previous one read, UART signal an "overrun" error via another status bit. The UART set up to interrupt the computer format the UART by the UART's control register incorrectly formated signal "framing/"parity error". Often the clock will run at 16 times the baud rate to read each bit in middle of its allotted time period makes the UART more tolerant to "jitter" stop bit extra "1" bits which follow the data and any parity bit. mark end of a byte or character). start bit signals the start of transmission oon a serial line zero-one transition tells receiver when to start sampling the signal to extract the data bits. synchronous Two or more processes common timing signals. asynchronous Not synchronised by shared clock , execution independently loser An unexpectedly bad situation, program,programmer Someone who habitually loses. (Even winners can lose ) Someone who knows not and knows not that he knows not. Emphatic forms real loser,total loser,complete loser" (not "moby loser", which is a contradiction in terms). RS-232C The EIA RS-232C electrical signal unbalanced +/- 5 to +/- 12V, polar non return to zero speeds up to 19.2 kilobits per second. DTE Data Terminal Equipment controls communication channel (terminals, computers) DCE Data Communication Equipment ...typically a modem IF "straight-through" cable (p1 to p1, p2 to p2 etc.) DTE should a male connector + trans on p3 and rece p2. gender mender gender bender,gender blender,sex changer,homosexualadaptor two male/female connectors used to correct mismatch RS-232 Originally DCE was modem and DTE was computer/terminal DCE RS-232 have female connector and tran p2 and rec p3 DTE RS-232 have male connector and tran p3 and rec p2 http://wombat.doc.ic.ac.uk/foldoc/ foldoc.cgi?hardware+handshaking TX ____ ____ TX | | RV ___/|\__| __ RV |_____| GND _____________ GND DTE DCE DTE: Data Terminal Equipment (terminal) DCE: Data Circuit-terminating Equipment (modem,computer) RS232C Max 20Kbps @ 15meters unbalanced Logic_0 "space" Vout +3V -> +15B Logic_1 "mark" Vout -3V -> -15V RS422 twisted pair balanced 10Mbps @ 12 meters .1Mbps@1.2Km _______ ___ _______ ___ ___ | S | D | D | D D | D D D | D | P | T |___| |___| |___________| |___| LSB MSB S=startBit D=data P=ParityBit 1=StopBit T=1/Baud 9600Baud=104.2us DTE Rdy Trans Recv Sig Det _ ___ _______ ___ _________ | ST| D0| D1| D2 D2| D4 D5 D6| D7| P | SB| : |___| |___| |___________| |___| | LSB MSB startBit ST data D ParityBit P StopBit 1 T 1/Baud 9600Baud= 104.2us Software Handshake XON and XOFF Hardware DTE DCE TX ____ ____ TX | | RV ___/|\__| __ RV |_____| RTS ___ ____ RTS | | CTS___/|\__| __ CTS |_____| GND _____________ GND RTS: Request to send CTS: Clear to send DTR: Data terminalready compu sets space_Hi so printer recev DSR: Data set ready printer sets space_Hi to receive DCD: Data carrier detect must space_Hi for printer to receiv n=0 is Speaker always off, n=0 is Speaker always on, n=1 is Speaker on until carrier detected (default) n=3 is Speaker on after dial through CONNECT O Return to on-line state P Pulse Dial Qn n=0 is send Resun Codes, n-1 is do not send code R Reverse mode (Originate Only) S0=n n=0 to 255 rings before answer (sees switch 5) S1=n n=0 to 127, count rings S2=n n=0 to 127, 43 default , Set escape code character S3=n n=0 to 127, 13 default , Set cr character S4=n n=0 to 127, 10 default, Set Line Feed character S5=n n=0 to 127, 8 default, Set Backspace character S6=n n=2 to 255, Wait for dial tone seconds S7=n n=2 to 255, Wait carrier detect seconds S8=n n=0 to 255, Set duration pause seconds S9=n Carrier detect response time seconds/10 S1O=n Delay time carrier loss to hang-up 1/10sec. Sll=n Duration a ndspace of Touch Tones ( 50ms to 255ms) S12=n Escape code guard time 1-255 1/10 sec S13=n UART status bit map (reserved) S14-n Option Register, product code returned by AT10 S15=n Flag Register(reserved) S16=n Self test mod�. n=O is data mode (default), n-1 is Analog Loopback, n=2 is dial test n=4 is Test Pattern, n=5 is Analog Loopback and Test Pattern. Sn? Send contents of Register n (0 to 16) to Computer T Touch Tone Dial Vn n-O is send resun�u�eo�d�d�B��-1 is wMds Xn n-B send basic result code 1 to 8 send extended resun codes B to 12 Z Somvare reset and reset to defaun values Hardware DTE DCE TX ____ ____ TX | | RV ___/|\__| __ RV |_____| RTS ___ ____ RTS ??????????? | | CTS___/|\__| __ CTS |_____| DTR ___ ____ DTR | | DSR___/|\__| __ DSR |_____| GND _____________ GND RTS: Request to send CTS: Clear to send DTR: Data terminalready DSR: Data set ready TXD: Transmit data RXD: Receive data RTS: Request to send (Pc sets this when ready to send ) CTS: Clear to send (modem ready to transmit ) DTR: Data terminalready (PC tells modem ready to send ) DSR: Data set ready (modem tells PC ready to transmit) CD: Carrier detect (modem sets this when detects PC) DTE: Data Terminal Equipment (terminal) DCE: Data Circuit-terminating Equipment (modem,computer) Half_dulplex data sent only in one direction at a time Full_dulplex data sent in both directions at a time Synchronous transmit data in blocks using sync characters 1baud one audio signal transitions per second FSK: Frequency_shift_Keying logic_0 = 1080Hz Logic_1 = 1750Hz 1baud =1bps PSK: Phase_shift_Keying logic_1/0 set by alternating carrier phase more bits per baud since phases are 0,90,180,270 QAM: Quadrature)_amplitude_modulation Both phase and frequency 1.7KHz or1.8Khz @ 2400baud only 4 bits usable per baud TCM: TCQAM or Trellic_coded quadrature_amplitude_modulation 6bits per baud. 14,400 bps modems use this CCITT V.XX Standards Consultative Committee InternalTelepho&Telegraph V.22 synch/asynch ,full duplex,2 wires, 1200bpsdata V.22bis synch/asynch ,full duplex,2 wires, 2400/1200bpsdata V.32 synch/asynch ,full duplex,2 wires, 9600bpsdata V.32bis synchs/asynch,full dupx,2wires,4.8K,7.2K,9.6K,12K,14.4Kbps V.34bis synchs/asynch,full dupx,2wires,28.8Kbps,speed<=line noise V.35 synchs/asynch ,full duplex,2 wires Bell stand : 0.3K,1.2K,2.4K,4.8Kbps TXD: Transmit data RXD: Receive data RTS: Request to send (Pc sets high when ready to send ) CTS: Clear to send (modem ready to transmit ) DTR: Data terminalready (PC tells modem ready to send ) DSR: Data set ready (modem tells PC ready to transmit) CD: Carrier detect (modem sets this when detects PC) DTE: Data Terminal Equipment (terminal) DCE: Data Circuit-terminating Equipment (modem,computer) ASCII American Standard Code for Information Interchange US-ASCII uses lower seven bits (character points 0 to 127) NUL Null DLE Data Link Escape SOH StartHeading DC1 Device Control 1 STX Start Text DC2 Device Control 2 ETX End Text DC3 Device Control 3 EOT End Trans DC4 Device Control 4 ENQ Enquiry EM End of Medium ACK Acknowledge SUB Substitute BEL Bell ESC Escape BS BackSpace FS File Separator HT Horizontal Tab GS Group Separator LF Line Feed RS Recorder Separator VT Vertical Tab US Unit Separator FF Form Feed DEL Delete CR Carriage Return SO Shift Out SI Shift In NAK Negative Ackno SYN Synch s Idle ETB End Trans Block CAN Cancel Give me a break! the canonical humorous response is "Control C". SOH Null ASCII_0 SOH Start Of Header ASCII_1 STX Start Of Text ASCII_2 ETX End Of Text ASCII_3 control-C Unix_interrupt EOT End Of Transmis ASCII_4 ENQ ENQuire. ASCII_5 ACK ACKnowledge ASCII_6 BEL sound bell ASCII_7 BS Backspace ASCII_8 HT tab ASCII_9 Control-I Unix => "\t" LF line feed ASCII_10 control-J Unix => "\n" VT Vertical Tab ASCII_11 FF form feed ASCII_12 Control-L CR CursReturn2Left ASCII_13 Control-M Unix => "\r" SO ShiftOut AltChars ASCII_14 Control-N SI ShiftIn AltChars ASCII_15 Control-O DLE Data Link Escape ASCII_16 DC1 resume output ASCII_17 control-Q XON DeviceControl1 DC2 DeviceControl2 ASCII_18 DC3 suspend output ASCII_19 control-S XOFF DeviceControl3 DC4 DeviceControl4 ASCII_20 NAK Neg Acknowledge ASCII_21 SYN Synchronous idle ASCII_22 ETB End Transm Block ASCII_23 CAN Cancel ASCII_24 Control-X EM End of Medium ASCII_25 SUB Substitute ASCII_26 ESC escape ASCII_27 ESCAPE FS File Separator ASCII_28 GS Group Separator ASCII_29 RS Record Separator ASCII_30 US Unit Separator ASCII_31 Hex Dec Char Hex Dec Char Hex Dec Char Hex Dec Char 00 00 NUL 20 32 space 40 64 @ 60 96 ` 01 01 SOH 21 33 ! 41 65 A 61 97 a 02 02 STX 22 34 " 42 66 B 62 98 b 03 03 ETX 23 35 # 43 67 C 63 99 c 04 04 EOT 24 36 $ 44 68 D 64 100 d 05 05 ENQ 25 37 % 45 69 E 65 101 e 06 06 ACK 26 38 & 46 70 F 66 102 f 07 07 EEL 27 39 ' 47 71 G 67 103 g 08 08 BS 28 40 ) 48 72 H 68 104 h 09 09 HT 29 41 ( 49 73 I 69 105 i GA 10 L 2A 42 * 4A 74 J 6A 106 j OB 11 VT 2B 43 + 4B 75 K 6B 107 k GC 12 FF 2C 44 , 4C 76 L 6C 108 I OD 13 CR 2D 45 - 4D 77 M 60 109 m GE 14 SO 2E 46 . 4E 78 N 6E 110 n OF 15 SI 2F 47 / 4F 79 O 6F 111 o 10 16 DLE 30 48 0 50 80 P 70 112 p 11 17 DC1 31 49 1 51 81 Q 71 113 q 12 18 DC2 32 50 2 52 82 R 72 114 r 13 19 DC3 33 51 3 53 83 S 73 115 s 14 20 DC4 34 52 4 54 84 T 74 116 t 15 21 NAK 35 53 5 55 85 U 75 117 u 16 22 SYN 36 54 6 56 86 V 76 118 v 17 23 ETB 37 55 7 57 87 W 77 119 w 18 24 CAN 38 56 8 58 88 X 78 120 x 19 25 EM 39 57 9 59 89 Y 79 121 y 1A 26 SUB 3A 58 : 5A 90 Z 7A 122 z 1E 27 ESC 3B 59 ; 5B 91 [ 7B 123 { 1C 28 FS 3C 60 < 5C 92 \ 7C 124 | 1D 29 GS 3D 61 = 5D 93 ] 70 125 } 1E 30 RS 3E 62 > 5E 94 ^ 7E 126 ~ 1F 31 US 3F 63 ? 5F 95 _ 7F 127 DE RS422 BALANCED DIFFERENTIAL DRIVERS Electronics Industry Association (EIA) has produced standards for RS485, RS422, RS232, and RS423 that deal with data communications. Compatibility With Other Interfaces Both RS-422 and RS-485 use a twisted-pair wire (i.e. 2 wires) for each signal. They both use the same differential drive with identical voltage swings: 0 to +5V. The main difference between RS-422 and RS-485 is that while RS-422 is strictly for point-to-point communications (and the driver is always enabled), RS-485 can be used for multidrop systems (and the driver has a tri-state capability). SPECIFICATIONS RS423 RS422 Mode of Operation SINGLE - ENDED DIFFERENTIAL Total Number of Drivers and Receivers on One Line 1 DRIVER 1 DRIVER 10 RECVR 10 RECVR Maximum Cable Length 4000 FT. 4000 FT. Maximum Data Rate 100kb/s 10Mb/s Maximum Driver Output Voltage +/-6V -0.25V to +6V Driver Output Signal Level (Loaded Min.) Loaded +/-3.6V +/-2.0V Driver Output Signal Level (Unloaded Max) Unloaded +/-6V +/-6V Driver Load Impedance (Ohms) >450 100 Max. Driver Current in High Z State Power On N/A N/A Max. Driver Current in High Z State Power Off +/-100uA +/-100uA Slew Rate (Max.) Adjustable N/A Receiver Input Voltage Range +/-12V -10V to +10V Receiver Input Sensitivity +/-200mV +/-200mV Receiver Input Resistance (Ohms) 4k min. 4k min. Characteristic Impedance (Ohms): A value based on the inherent conductance, resistance, capacitance and inductance of a cable that represents the impedance of an infinitely long cable. When the cable is out to any length and terminated with this Characteristic Impedance, measurements of the cable will be identical to values obtained from the infinite length cable. That is to say that the termination of the cable with this impedance gives the cable the appearance of being infinite length, allowing no reflections of the transmitted signal. If termination is required in a system, the termination impedance value should match the Characteristic Impedance of the cable. Shunt Capacitance (pF/ft): The amount of equivalent capacitive load of the cable, typically listed in a per foot basis One of the factors limiting total cable length is the capacitive load. Systems with long lengths benefits from using low capacitance cable. Propagation velocity (% of c): The speed at which an electrical signal travels in the cable. The value given typically must be multiplied by the speed of light (c) to obtain units of meters per second. For example, a cable that lists a propagation velocity of 78% gives a velocity of 0.78 X 300 X 106 - 234 X 106 meters per second. Plenum cable Plenum rated cable is fire resistant and less toxic when burning than non-plenum rated cable. Check building and fire codes for requirements. Plenum cable is generally more expensive due to the sheathing material used. The RS-422 specification recommends 24AWG twisted pair cable with a shunt capacitance of 16 pF per foot and 100 ohm characteristic impedance. While the RS-485 specification does not specify cabling, these recommendations should be used for RS485 systems as well. It can be difficult to quantity whether shielding is required in a particular system or not, until problems arise. We recommend erring on the safe side and using shielded cable. Shielded cable is only slightly more expensive than unshielded. There are many cables available meeting the recommendations of RS-422 and RS-485, made specifically for that application. Another choice is the same cable commonly used in the misted pair Ethernet cabling. This cable, commonly referred to as Category 5 cable, is defined by the ElA/TIA/ANSI 568 specification The extremely high volume of Category 5 cable used makes it widely available and very inexpensive, often less than half the price of specialty RS422/485 cabling. The cable has a maximum capacitance of 17 pF/ft (14.5 pF typical) and characteristic impedance of 100 ohms. Category 5 cable is available as shielded twisted pair (STP) as well as unshielded twisted pair (UTP) and generally exceeds the recommendations for RS-422 making it an excellent choice for RS-422 and RS-485 systems.