Serial Cable Types and Details
From Free Knowledge Base- The DUCK Project: information for everyone
# Serial Cable Types and Details # # Thu Sep 15 15:05:45 CDT 2005 # ###############################################################################
Contents
Commercial names for available serial cable types:
- PC Serial Printer Cable
- AT Serial Modem Cable
- AT Serial Printer Cable
- XT Serial Modem Cable
- PC Serial Null Modem Cable
- RS-449 DB37 Serial Cable
- Laplink File Transfer Serial Cable
Serial Termonology:
- DTE Data Terminal Equipment
- DCE Data Communication Equipment
RS232 25pin -vs- 9pin
RS232 serial first used 25pin DB25 connectors which were provisioned for a seldom used a secondary serial RS232 communication channel. Sun SparcStation 10 and 20 models, Dec Alpha Multia, and some Telebit modems were able to utilize the secondary channel.
DB9 - DB25 conversion
DB9 DB25 Function 1 8 Data carrier detect 2 3 Receive data 3 2 Transmit data 4 20 Data terminal ready 5 7 Signal ground 6 6 Data set ready 7 4 Request to send 8 5 Clear to send 9 22 Ring indicator
RS232 null modem cables
Two PC's can be easily connected with a Null Modem cable. Typical PC connectors are 9pin DB9.
The most expensive null modem cable is the null modem cable suitable for full handshaking. In this null modem cable, seven wires are present. Only the ring indicator RI and carrier detect CD signal are not linked.
DB-9 Pinouts for RS-232
Engineers recognize 4 types of Null Modem Cable:
1. Cable Without Handshaking SFC --- --- --- 2. Loop Back Handshaking SFC LDE HDE --- 3. Partial Handshaking SFC LDE HDE FAS 4. Full Handshaking SFC --- --- FAS ` SFC = Software Flow Control HDE = DTE/DCE Hardware Flow Fast LDE = DTE/DCE Hardware Flow Slow FAS = Software High Speed
