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Common names: EIA-449, RS-449, ISO 4902<br>
''Primary channel''

== Pinout ==

[[Image:dsub37m.png]]

37 PIN D-SUB MALE at the DTE (Computer).

[[Image:dsub37f.png]]

37 PIN D-SUB FEMALE at the DCE (Modem).

CORRECT?

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

<i>Note: Direction is DTE (Computer) relative DCE (Modem).''

{| {{border}}
! Name  !! Description                                       !! Function
|-
| AA    || Shield Ground                                     || Also known as protective ground. This is the chassis ground connection between DTE and DCE.
|-
| AB    || Signal Ground                                     || The reference ground between a DTE and a DCE. Has the value 0 Vdc.
|-
| 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                                     || 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.
|-
| CC    || DCE Ready                                         || Known as DSR. Originated by the DCE indicating that it is basically operating (power on, and in functional mode).
|-
| CD    || DTE Ready                                         || 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.
|-
| CE    || Ring Indicator                                    || A signal from the DCE to the DTE that there is an incomming call (telephone is ringing). Only used on switched circuit connections.
|-
| CF    || Received Line Signal Detector                     || 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.
|-
| CH/CI || Data Signal Rate Select<br>(DTE/DCE Source>       || A control signal that can be used to change the transmission speed.
|-
| DA    || Transmit Signal Element Timing<br>(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<br>(DCE Source) || Timing signals used by the DTE for transmission.
|-
| DD    || Receiver Signal Element Timing<br>(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. 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
|-
| RC    || Receive Common                                    || A signal return for receiver circuit reference
|-
| LL    || Local Loopback / Quality Detector                 || A control signal from the DTE to the DCE that causes the analog transmision 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 the analog signal and thus causing a line 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.
|-
|       || Reserved for Testing                              ||
|}

== Contributions ==
* [[User:Joakim|Joakim Ögren]]

== Sources ==
* [http://www.made-it.com/CKP/rs449.html RS449 Page] at [http://www.made-it.com/CKP/ Connectivity Knowledge Platform (Made IT)]

[[Category:Connector]]
[[Category:Serial]]