A Made IT project

RS449

General
The RS449 interface is a generic connector specification. It's not an actual interface. The connector pinning was originally designed to support RS422 for balanced signals, and RS423 for the unbalanced signals. And should have been the succesor of RS232.


Male	Female

Pin	Signal	Abbr.	DTE	DCE
1	Shield
2	Signal Rate Indicator	S	Out	In
3	Unassigned
4	Send Data (A)	SD-	Out	In
5	Send Timing (A)	ST-	In	Out
6	Receive Data (A)	RD-	In	Out
7	Request To Send (A)	RS-	Out	In
8	Receive Timing (A)	RT-	In	Out
9	Clear To Send (A)	CS-	In	Out
10	Local Loopback	LL	Out	In
11	Data Mode (A)	DM-	In	Out
12	Terminal Ready (A)	TR-	Out	In
13	Receiver Ready (A)	RR-	In	Out
14	Remote Loopback	RL	Out	In
15	Incoming Call	IC	In	Out
16	Signal Freq./Sig. Rate Select.	SF/SR+	In/Out	Out/In
17	Terminal Timing (A)	TT-	Out	In
18	Test Mode (A)	TM-	In	Out
19	Signal Ground	SG
20	Receive Common	RC
21	Unassigned
22	Send Data (B)	SD+	Out	In
23	Send Timing (B)	ST+	In	Out
24	Receive Data (B)	RD+	In	Out
25	Request To Send (B)	RS+	Out	In
26	Receive Timing (B)	RT+	In	Out
27	Clear To Send (B)	CS+	In	Out
28	Terminal In Service	IS	Out	In
29	Data Mode (B)	DM+	In	Out
30	Terminal Ready (B)	TR+	Out	In
31	Receiver Ready (B)	RR+	In	Out
32	Select Standby	SS	In	Out
33	Signal Quality	SQ	In	Out
34	New Signal	NS	Out	In
35	Terminal Timing (B)	TT+	Out	In
36	Standby Indicator	SB	In	Out
37	Send Common	SC


Male	Female

Pin	Signal	Abbr.
1	Shield
2	Secondary Receiver Ready	SSR
3	Secondary Send Data	SSD
4	Secondary Receive Data	SRD
5	Signal Ground	SG
6	Receive Common	RC
7	Secondary Request To Send	SRS
8	Secondary Clear To Send	SCS
9	Send Common	SC

Functional description
Since RS449 is only a newer version of RS232 we will only describe the new signals.

Description	Circuit	Function
Shield Ground	AA	Also known as protective ground. This is the chassis ground connection between DTE and DCE.
Signal Ground	AB	The reference ground between a DTE and a DCE. Has the value 0 Vdc.
Transmitted Data	BA	Data send by the DTE.
Received Data	BB	Data received by the DTE.
Request To Send	CA	Originated by the DTE to initiate transmission by the DCE.
Clear To Send	CB	Send by the DCE as a reply on the RTS after a delay in ms, which gives the DCEs enough time to energize their circuits and synchronize on basic modulation patterns.
DCE Ready	CC	Known as DSR. Originated by the DCE indicating that it is basically operating (power on, and in functional mode).
DTE Ready	CD	Known as DTR. Originated by the DTE to instruct the DCE to setup a connection. Actually it means that the DTE is up and running and ready to communicate.
Ring Indicator	CE	A signal from the DCE to the DTE that there is an incomming call (telephone is ringing). Only used on switched circuit connections.
Received Line Signal Detector	CF	Known as DCD. A signal send from DCE to its DTE to indicate that it has received a basic carrier signal from a (remote) DCE.
Data Signal Rate Select (DTE/DCE Source>	CH/CI	A control signal that can be used to change the transmission speed.
Transmit Signal Element Timing (DTE Source)	DA	Timing signals used by the DTE for transmission, where the clock is originated by the DTE and the DCE is the slave.
Transmitter Signal Element Timing (DCE Source)	DB	Timing signals used by the DTE for transmission.
Receiver Signal Element Timing (DCE Source)	DD	Timing signals used by the DTE when receiving data.
terminal In Service	IS	Signal that indicates that the DTE is available for operation
New Signal	NS	A control signal from the DTE to the DCE. It instructs the DCE to rapidly get ready to receive a new analog signal. It helps master-station modems rapidly synchronize on a new modem at a tributary station in multipoint circuits
Receive Common	RC	A signal return for receiver circuit reference
Local Loopback / Quality Detector	LL	A control signal from the DTE to the DCE that causes the analog transmision output to be connected to the analog receiver input.
Remote Loopback	RL	Signal from the DTE to the DCE. The local DCE then signals the remote DCE to loopback the analog signal and thus causing a line loopback.
Standby Indicator	SB	Signal from the DCE to indicate if it is uses the normal communication or standby channel
Send Common	SC	A return signal for transmitter circuit reference
Select Frequency	SF	A signal from the DTE to tell the DCE which of the two analog carrier frequencies should be used.
Select Standby	SS	A signal from DTE to DCE, to switch between normal communication or standby channel.
Test Mode	TM	A signal from the DCE to the DTE that it is in test-mode and can't send any data.
Reserved for Testing

The secondary signals are used on some DCE's. Those units have the possibility to transmit and/or receive on a secondary channel. Those secondary channels are mostly of a lower speed than the normal ones and are mainly used for administrative functions.

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