Appendix C – Electrical Interface
Sealevel Systems
COMM+850.PCI
Page
8
Appendix C - Electrical Interface
RS-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. The IBM PC computer defined the
RS-232 port on a 9 pin D sub connector and subsequently the EIA/TIA approved
this implementation as the EIA/TIA-574 standard. This standard is defined as
the
9-Position Non-Synchronous Interface between Data Terminal
Equipment and Data Circuit-Terminating Equipment Employing Serial
Binary Data Interchange
. Both implementations are in wide spread use and
will be referred to as RS-232 in this document. 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 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. The
RS-232 and the EIA/TIA-574 specification define two types of interface
circuits, Data Terminal Equipment (DTE) and Data Circuit-Terminating
Equipment (DCE). The
COMM+850.PCI
is a DTE device.
