DTE-DCE Interface Cont

o    EIA  232  calls  for  a  25  wire  cable  terminated  at  one  end  by  by  a  male connector and at the other end by a female connector o    Male refers to a plug with each wire in the cable attaching to a pin o    Female refers to a receptacle with each wire in cable connecting to a metal tube or sheath    Electrical Specifications (Sending data) o    EIA  232  states  that  data  must  be  tx  as  binary  1's  and  0's  using  NRZ-L encoding with 0 defines as a positive and 1 defined as a negative voltage o    However  rather  than  defining  a  single  range  bounded  by  highest  and lowest  amplitudes,  EIA  232  defines  two  distinct  ranges  ,  one  for  +ve voltages and one for -ve o    The  receiver  accepts  any  voltage  that  falls  within  these  ranges  as  valid signals o    To be recognized as data, the amplitude of the signal must fall b/w 3 and 15 volts or b/w -3 and -15 volts o    Degradation of noise will in misinterpretation of bits o    A square wave is shown to be converted into a curve by noise and it covers many voltages o    If  the  rx  were  looking  for  a  fixed  voltage,  or  only  for  pulses  that  held  a single  voltage  for  their  entire  duration,degradation  would  have  made  it unrecoverable. •     Electrical Specifications (Control & Timing) o    Only 4 wires out of 25 in EIA 232 are used for data functions. o    Remaining  21  are  reserved  for  functions  like  Control,  Timing, Grounding and Testing o    Any  of  the  functions  is  considered  ON  if  it  transmits  a  voltage  of