1. DATA COMMUNICATION
Lecture-21

2. Recap of Lecture 20 Introduction to Interfaces
Digital Data Transmission
Parallel Transmission
Serial Transmission
Asynchronous Transmission
Synchronous Transmission

3. Overview of Lecture 21 DTE-DCE Interface DTE-DCE Interface Standards
EIA-232
Null Modem
EIA-449

4. DTE and DCE DTE (Data Terminal Equipment)
Any device that is a source of or destination of digital data
DCE (Data Circuit terminating Equipment)
Any device that transmits/receives signal through network

5. DTE and DCE

6. DTE-DCE Interface Standards

7. EIA-232 Interface Originally RS-232 issued in 1962
Mechanical specification
DB-25 pin connector, 15-meter cable
DB-9 pin connectors are also available

8. Sending Data in EIA-232

9. Control Signals in EIA-232

10. Functional Specification

11. EIA-232 Functioning Step 1: Preparation Step 2: Readiness
Preparation of the interface between DTE and DCE
Step 2: Readiness
Checks if all four devices are ready

12. EIA-232 Functioning Step 3: Set up Step 4: Data Transfer
Set up the connection between two DCEs
Step 4: Data Transfer
DTE -> DCE -> DCE -> DTE

13. EIA-232 Functioning
Step 5: Clearing
Turning OFF the connection

14. Functioning of EIA-232 in Synchronous Full Duplex Mode

16. Null Modem DTE-DTE interface without DCEs
Especially cabled two Female DB-25 Connectors

17. Null Modem

18. Null Modem

19. Summary DTE-DCE Interface DTE-DCE Interface Standards EIA-232
Null Modem

20. Suggested Reading
Section 6.2,6.3, “Data Communications and Networking” 2nd Edition by Behrouz A. Forouzan