Impulse 5103 - Manual (Page 9)

Appendix C - Electrical Interface
Sealevel Systems ACB-MP.PCI Page 7
Appendix C - Electrical Interface
RS-232 Or EIA/TIA-232
Quite possibly the most widely used communication standard is RS-232. This implementation has been defined and
revised several times and is often referred to as RS-232 or EIA/TIA-232. It is defined by the EIA as the Interface
between Data Terminal Equipment and Data Circuit- Terminating Equipment Employing Serial Binary Data
Interchange. The mechanical implementation of RS-232 is on a 25-pin D sub connector. RS-232 is capable of
operating at data rates up to 20 Kbps at distances less than 50 ft. The absolute maximum data rate may vary due to
line conditions and cable lengths. RS-232 often operates at 38.4 Kbps over very short distances. The voltage levels
defined by RS-232 range from -12 to +12 volts. RS-232 is a single ended or unbalanced interface, meaning that a
single electrical signal is compared to a common signal (ground) to determine binary logic states. A voltage of +12
volts (usually +3 to +10 volts) represents a binary 0 (space) and -12 volts (-3 to -10 volts) denotes a binary 1 (mark).
The RS-232 and the EIA/TIA-574 specification defines two type of interface circuits, Data Terminal Equipment
(DTE) and Data Circuit-Terminating Equipment (DCE). The Sealevel Systems adapter is a DTE interface.