EIA-449 Connector Pin Out and Signal Assignments (RS-449 Pinout)

EIA-449 Pinout, Signal Assignments

The EIA/TIA-449 is a general purpose 37-Position Interface for Data terminal Equipment and Data Circuit-Terminating Equipment Employing Serial binary Data Interchange

EIA-449 cabling uses EIA-422 differential pairs to send and receive data, and EIA-423 single-ended lines to send and receive control signals.

V.35/RS449 Cable Length Recommendations; The cable length will determine maximum bus speed, or the maximum transfer rate is determined by the cable length.
Length of Cable x Maximum Data Thru-put:
2Mbps data transfer out to 50 feet of cable, maximum [15 meters],
1Mbps data rates with 100 feet of cable,
512kbps to 200 feet, 256kbps to 400 feet, 128kbps to 800 feet, 56kbps to 1600 feet,
1.2kbps out to a maximum cable length of 3000 feet [914 meters].
V.24 is also listed in the pin-out table, many interfaces use RS422 and RS423 electrical standards.
V.24 was rated at 20 kbps with a maximum range of about 15 meters.

The pinout for the 37-pin connector is listed below.
The pin out for the 9-pin connector is listed on the main EIA-449 Bus page.

**RS449 Bus Connector Pin Out**
Pin	Name	V.24	Description	Type
1		101	Shield	Ground
2	SI	112	Signal Rate Indicator	Control
3	n/a		unused
4	SD-	103	Send Data (A)	Data
5	ST-	114	Send Timing (A)	Timing
6	RD-	104	Receive Data (A)	Data
7	RS-	105	Request To Send (A)	Control
8	RT-	115	Receive Timing (A)	Timing
9	CS-	106	Clear To Send (A)	Control
10	LL	141	Local Loopback	Control
11	DM-	107	Data Mode (A)	Control
12	TR-	108.2	Terminal Ready (A)	Control
13	RR-	109	Receiver Ready (A)	Control
14	RL	140	Remote Loopback	Control
15	IC	125	Incoming Call	Control
16	SF/SR+	126	Signal Freq./Sig. Rate Select.	Control
17	TT-	113	Terminal Timing (A)	Timing
18	TM-	142	Test Mode (A)	Control
19	SG	102	Signal Ground	Ground
20	RC	102b	Receive Common	Ground
21	n/a		unused
22	SD+	103	Send Data (B)	Data
23	ST+	114	Send Timing (B)	Timing
24	RD+	104	Receive Data (B)	Data
25	RS+	105	Request To Send (B)	Control
26	RT+	115	Receive Timing (B)	Timing
27	CS+	106	Clear To Send (B)	Control
28	IS	n/a	Terminal In Service	Control
29	DM+	107	Data Mode (B)	Control
30	TR+	108.2	Terminal Ready (B)	Control
31	RR+	109	Receiver Ready (B)	Control
32	SS	116	Select Standby	Control
33	SQ	110	Signal Quality	Control
34	NS	n/a	New Signal	Control
35	TT+	113	Terminal Timing (B)	Timing
36	SB	117	Standby Indicator	Control
37	SC	102a	Send Common	Ground

V.35/RS449 Max length
Data Rate	Cable Length
2 Mb/sec	15.24 Meters
1 Mb/sec	30.48 Meters
512 Kb/sec	60.96 Meters
256 Kb/sec	121.92 Meters
128 Kb/sec	243.84 Meters
56 K	487.68 Meters
1.2 Kb/sec	914.40 Meters

**EIA449 Pin Designations and Descriptions**
Name	Description	Function
AA	Shield Ground	Protective ground. Chassis ground connection between DTE and DCE.
AB	Signal Ground	Ground
BA	Transmitted Data	Data send by the DTE.
BB	Received Data	Data received by the DTE.
CA	Request To Send	Originated by the DTE to initiate transmission by the DCE.
CB	Clear To Send	----
CC	DCE Ready	DSR. Originated by the DCE indicating that it is operating
CD	DTE Ready	DTR. Originated by the DTE to instruct the DCE to setup a connection
CE	Ring Indicator	Signal from the DCE to the DTE that there is an in-comming call
CF	Received Line Signal Detector	DCD. A signal send from DCE to its DTE to indicate that it has received a basic carrier signal from a (remote) DCE.
CH/CI	Data Signal Rate Select DTE/DCE Source	A control signal that can be used to change the transmission speed.
DA	Transmit Signal Element Timing (DTE Source)	Timing signals used by the DTE for transmission, where the clock is originated by the DTE and the DCE is the slave.
DB	Transmitter Signal Element Timing (DCE Source)	Timing signals used by the DTE for transmission.
DD	Receiver Signal Element Timing (DCE Source)	Timing signals used by the DTE when receiving data.
IS	terminal In Service	Signal that indicates that the DTE is available for operation
NS	New Signal	A control signal from the DTE to the DCE. Instructs the DCE to rapidly get ready to receive a new analog signal
RC	Receive Common	A signal return for receiver circuit reference
LL	Local Loopback / Quality Detector	Control signal from the DTE to DCE that causes the analog transmission output to be connected to the analog receiver input.
RL	Remote Loopback	Signal from the DTE to the DCE. The local DCE then signals the remote DCE to loopback
SB	Standby Indicator	Signal from the DCE to indicate if it is uses the normal communication or standby channel
SC	Send Common	A return signal for transmitter circuit reference
SF	Select Frequency	A signal from the DTE to tell the DCE which of the two analog carrier frequencies should be used.
SS	Select Standby	A signal from DTE to DCE, to switch between normal communication or standby channel.
TM	Test Mode	A signal from the DCE to the DTE that it is in test-mode and can't send any data.

RS449 is the old term for EIA449. The term RS [Recommended Standard] was replaced in the 70's by the term EIA.
However as of 2011 the EIA group disbanded, which would make this the TIA449 interface.

Back to the main EIA-449 Bus page for a description and pinout of a 9-Pin D connector.

Navigation: Engineering Home > Interface Buses > Cabled Interface Standards > EIA-449 Bus > RS449 variations.


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