From G8MNY@4:902/6 to WW on Wed Dec 11 05:57:59 2024
To : IBM@WW
25 Way D-Type Serial:
1 - NC 7 - Signal Ground
2 - Transmit Data 8 - Carrier Detect 1 13 3 - Receive Data 9-19 - NC x x x x x x x x x x x x x
4 - Request To Send 20 - Data Terminal Ready x x x x x x x x x x x x
5 - Clear To Send 21 - NC 14 25
6 - Data Set Ready 22 - Ring Indicate
23-25 - NC
9 Pin D-Type Serial:
1 - Carrier Detect 6 - Data Set Ready 1 5
2 - Receive Data 7 - Request To Send x x x x x
3 - Transmit Data 8 - Clear To Send x x x x
4 - Data Terminal Ready 9 - Ring Indicate 6 9
5 - Signal Ground
RS-232C INTERFACE STANDARD (25Way)
DTE (e.g. computer) ! DCE (e.g. Modem)
Data Terminal Equipment ! Data Communications Equipment
Signal EIA / CCITT Pin Telephone Co. Signal
Direct Line Name No. Lead No Direction
- Protective Ground 1 AA/101 -
- Signal Ground 7 AB/102 -
- Transmitted Data 2 BA/103 >
< Received Data 3 BB/104 -
- Request to Send 4 CA/105 >
< Clear to Send 5 CB/106 -
< Data Set Ready 6 CC/107 -
- Data Terminal Ready 20 CD/108.2 >
- Connect Data Set to line 20 * /108.1 >
< Received Line Signal Detector 8 CF/109 -
- Speed Select 23 CH/111 >
< Transmit Signal Element Timing 15 DB/114 -
< Receive Signal Element Timing 17 DD/115 -
- Select Standby 11 * /116 >
< Ring Indicator 22 DE/125 -
- Test 18 * /* >
* means non-defined/standardized by EIA / CCITT
Line Loads are not < 3kê, & not > 7kê.
Voltages not >ñ3V & not <ñ15V on load, <ñ24V for no load.
Switched Timing Sequence (dial-up modem line communication)
_________________________________________
Data Terminal Ready ___!
______________________________________
Data Set Ready ______!
_______________________
Request To Send _________! !___________
________________________
Clear To Send ____________! !_______
_________________
Transmitted Data _______________! !___________
Nonswitched Timing Sequence (direct line connection)
_________________________________________
Data Terminal Ready ___!
______________________________________
Data Terminal Ready ______!
_______________________
Request To Send _________! !___________
________________________
Clear To Send ____________! !_______
_____________
Transmitted Data _______________! !_______________
-------------------------------------------------------------------
IBM PC-AT Serial cable DB25 to DB9
serial adapter on computer (cable connector is female)
Signal Direction
25 pin 9 pin Cable-Computer
DB25 DB9 DCE-ADAPTER
8 Carrier Detect 1 >
3 Received Data 2 >
2 Transmitted Data 3 <
20 Data Terminal Ready 4 <
7 Signal Ground 5 -
6 Data Set Ready 6 >
4 Request to send 7 <
5 Clear To Send 8 >
22 Ring Indicator 9 >
All other pins on the 25 pin connector are unused. --------------------------------------------------------------------
RS232 x connections. Comprehensive RS-232 computer to Tnc cross reference Jumpers if needed, on a three wire RS232. AT the COMPUTER end only.
--------
DB-25: DE-9:
RTS CTS RTS CTS
4----5 7----8
6----8---20 1----4----6
DSR DCD DTR DCD DTR DSR
RS-232 Serial port "3 Wire" Cable wiring for DB-25 to DE-9 or DE-25.
Computer DB-25 TNC DE-9 TNC(type 2)DB-25s.
TO OR
1 & 7 ----------- 5 ------------- 1
2 --------------- 3 ------------- 2
3 --------------- 2 ------------- 3 ---------------------------------------------------------------------
RS-232 Serial port "3 Wire" Cable wiring for DE-9 to DE-9 or DE-25.
Computer DE-9 TNC DE-9 TNC(type 2)DB-25s.
TO OR
5 & Shell ------- 5 ------------ 1
2 --------------- 2 ------------ 3
3 --------------- 3 ------------ 2 ------------------------------------------------------------------
"Eight-Wire" RS-232 Cable (conventional)
Computer to TNC
DB-25 or DE-9 to DE-9p or DB-25S
1 shell ---------------- 5 1
2 3 ---------------- 3 2
3 2 ---------------- 2 3
4 7 ---------------- 7 n/c
5 8 ---------------- 8 5
6 6 ---------------- 6 6
7 5 ---------------- 5 7
8 1 ="connected sig" 1 8
20 4 ---------------- n/c 20 ------------------------------------------------------------------
Serial Port Cross Reference.
Conventional IBM AT TNC-320 TNC_2
DB-25 p/s De-9P DE-9p DB-25s
pin Function
FGround 1 shell 5 1
Txd 2 3 3 2
RxD 3 2 2 3
RTS 4 7 7 n/c
CTS 5 8 8 5
DSR 6 6 6 6
Sig Earth 7 5 5 7
DCD 8 1 1 (a) 8 (a
test 9 V+ - +12 V
test 10 V- - -12 V
DTR 20 4 n/c 20
RI 22 9 9 (b) (23)
(a) This line goes high when a connection exists.
(b) RFDCD (Also used for multi_node NET/ROM & ROSE)