RS-232-G (EIA-232) is best described as which kind of interface standard in data communications?
-
Ais an interface between two data circuit terminating equipment as exemplified by a local and remote modem
-
Bis an interface standard between Data Terminal Equipment (DTE) and Data Circuit-Terminating Equipment (DCE)
-
Cspecifies only the mechanical aspects by providing a 25-pin connector
-
Drequires only 7 pins out of 25 to transmit digital data over public telephone lines
-
ENone of the above
Answer
Correct Answer: is an interface standard between Data Terminal Equipment (DTE) and Data Circuit-Terminating Equipment (DCE)
Explanation
Introduction:Serial communication between computers and modems historically relied on a widely adopted interface standard. Recognizing what RS-232-G (EIA-232) truly standardizes helps differentiate electrical, mechanical, and functional aspects of classic serial links.
Given Data / Assumptions:
- Devices are categorized as DTE (e.g., a computer/terminal) and DCE (e.g., a modem).
- Interfacing requires agreed voltage levels, signal assignments, and connectors.
- The question seeks the best high-level description of RS-232-G.
Concept / Approach:RS-232-G is an interface standard between DTE and DCE. It specifies electrical characteristics (voltage levels for mark/space), signal functions (TXD, RXD, RTS, CTS, DTR, DSR, etc.), and recommended mechanical connectors (such as the 25-pin or 9-pin variants). It does not limit itself to pin count or purely mechanical form; nor is it intended for DCE-to-DCE interconnection alone.
Step-by-Step Solution:1) Identify the endpoints: DTE ↔ DCE (e.g., terminal ↔ modem).2) Recall that RS-232 defines voltage and signaling conventions enabling these endpoints to interoperate.3) Note that while DB-25 was common, RS-232 is not “mechanical-only.”4) Conclude the most accurate description: a DTE–DCE interface standard.
Verification / Alternative check:Manufacturer datasheets and EIA documentation consistently frame RS-232 as a DTE–DCE serial interface specification.
Why Other Options Are Wrong:
- Two DCEs (option A): RS-232 is not specifically for DCE–DCE.
- Mechanical-only (option C): ignores electrical/signaling definitions.
- 7 pins only (option D): pin usage varies; the standard defines many control signals beyond a minimal subset.
- None of the above: invalid because the DTE–DCE description is correct.
Common Pitfalls:Assuming connector shape equals the full standard; RS-232 encompasses signaling semantics and voltage levels as well.
Final Answer:is an interface standard between Data Terminal Equipment (DTE) and Data Circuit-Terminating Equipment (DCE)